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Ape Factory
11-03-2018, 07:33 PM
I'm about to service all of the fluids in the S-Tronic DL501 transmission as well as the 0BF sport rear differential and ordered everything needed. Not all the fluids are in need of changing currently (I'm at 50K and change) but I'm doing so anyway as maintenance above and beyond. This thread will have a full write-up along with photos and videos as I have time to get everything edited and posted. I spent a lot of time reading and researching and feel I've made fluid improvements where I have enough information to make a viable determination as to what better is. Where I don't have enough info, I'm sticking to OEM.

Some of the material is common knowledge to the regulars but I'm throwing it in here for anyone who joins the forum and doesn't know the basics.

Let's start out with the rear differential. The RS5's rear differential is a "sport differential" and it's active (I believe Audi calls this EDL). It's shared with a number of other Audis including the S4, S5, S6 but may have programming or internal differences from other models. It's often referred to as the OBF differential.

The differential uses two different fluids. One is a GL5 or "MTF" gear fluid, the other is an "ATF" style fluid of unknown specifications. MTF=manual transmission fluid, ATF=automatic transmission fluid. It's an oversimplification technically but works fine for maintenance purposes. The MTF side is where the ring and pinion gear is. The ATF side controls the active differential hydraulics and clutch packs.

Here's a video on how the rear differential works:

https://youtu.be/rQowh2Kr38s

Servicing The Rear Differential

Rear Differential OEM fluid Part Numbers
VAG G 052 145 S2 "MTF" side
VAG G 055 515 A2 "ATF" side

VAG G 052 145 S2 is essentially a GL5 75w90 synthetic gear oil. I plan on substituting that fluid for Motul Gear 300 100% synthetic gear oil as it has a very high VI (222) and it's viscosity doesn't change as much with temperature. I'm usually up to speed on the highway before everything is fully warmed up. My engine oil temps are usually around 160 and I've logged transmission temperatures, in the summer, and it takes a good ten minutes at highway speed to get things up to temperature. The Motul flows well when it's cold and states it has zero shear.

The specifications for the ATF fluid, G 055 515 A2 are unknown. I cannot find them anywhere nor any manufacturer who recommends a product they make except for Ravenol. I'll be sticking with the OEM fluid then! It ain't cheap, around $45 for one liter. Luckily you only need one.

Aftermarket G 055 515 A2-compatible Rear Differential ATF Fluids

Ravenol Transfer Fluid TF-0870 (meets G052515A2/055515A2)
https://www.ravenol.de/en/products/usage/d/Product/show/p/ravenol-transfer-fluid-tf-0870.html

Aftermarket G 052 145 S2 compatible Rear Differential MTF Fluids

We're going to start with Motul as they've managed to make things complicated. If you go to their oil selector page and choose the RS5 MY 2010-11, they have different options from 2012-2016

MY 2010-11; https://www.motul.com/us/en-US/lubricants/recommendations/53c4e9b2c2960e9a83fdd54d46d9ac65?type_name=RS5+4.2 +FSI+quattro+%282010-2011%29

MY 2012+ ; https://www.motul.com/us/en-US/lubricants/recommendations/c1f4ff1812632044b9f2a18d4ccb91cc?type_name=RS5+4.2 +FSI+quattro+%282012-2016%29

Why, Motul why???? So they recommend the Gear 300 LS and the specs aren't nearly as good as the non-LS (limited slip) version. Their literature even says the Gear 300 is for diffs with no limited slip. Remember, we have two chambers and the gear fluid doesn't come in contact with the active diff components. That's handled by the ATF side. So keep that in mind.

Motul*Gear 300 LS 75W-90 (Motuls recommendation) SAE J 306
Colour Green
Viscosity grade 75W-90
Density at 20C (68F)
Viscosity at 40C (104F) 109.6
Viscosity at 100C (212F) 16.4
Viscosity index 161
Flash point 200C / 392F 
Pour point -42C / -43.6F

MOTUL GEAR 300 75W-90 (SAE J306) Look at the viscosity @40C! Amazing.
Viscosity grade 75w-90
Density at 20C (68F) 0.897
Viscosity at 40C (104F) 72.6 mm2/s
Viscosity at 100C (212F) 15.2 mm2/s
Viscosity index 222
Flash point 392F
Pour point -60C
*
Redline MT90
API Service Class GL 4
SAE Viscosity Grade (Gear Oil) 75W90
SAE Viscosity Grade (Motor Oil) 15W40
Vis @ 100C, CSt 15.5
Vis @ 40C, CSt 86.2
Viscosity Index 194
Pour Point, C -45
Pour Point, F -49
*
Amsoil SAE 75W-90 Gear Lube (G052145S2 Cert)
Kinematic Viscosity @ 100C,16.6
Kinematic Viscosity @ 40C, 129.7
Viscosity Index 137
Brook eldViscosity,cP(ASTMD2983) 98,300@-40C
Flash Point, C (F) (ASTM D92) 214 (417)
PourPoint,C(F)(ASTMD97) -51(-60)

*
Ravenol VSG SAE 75W-90 (G052145S2 Cert)
Density at 20C* kg/m*** 864********
Viscosity at 100C 16,5**
Viscosity at 40C 96,8****
Viscosity index VI 185
Brookfield Viscosity 40.500
Pourpoint**C -57***
Flash point (COC) 226C 438F
*
Liqui-Moly Gear Oil SAE 75W-90 GL4+ (G052145S2 Cert)
SAE class (gear oils)75W-90 SAE J306
Density at 15 C 0,855 g/cm3
Viscosity at 40 C 81,5
Viscosity at 100 C 14,3
Viscosity at -40C (Brook- field)<= 150000 mPas ASTM D 2983-09
Viscosity index 183
Pour point -60 C
Flash point200 C
*
Fuchs Titan Sintopoid SAE 75W-90
No specs yet...

Rear Differential Parts list
-G 052 145 S2 (1 Liter needed) Can substitute with another approved oil that meets specs.
-G 055 515 A2 (1 Liter needed) Stick to OEM fluid $45 approx.
(4)Fill/drain plugs with integrated washer Mfg. # N90281802 (4 needed) $3.40ea, $13.60 total
***I went with Motul Gear 300 75w90 for the G 052 145 S2 specification (1 Liter) $22


The transmission in the RS5 is the 7-speed S-Tronic DL501, sometimes called OB5. It integrates a front and center differential and is a "dual clutch" transmission (DCT). This transmission is also used in the supercharged S4/S5, S6, S7 as well as other models. Again, it may have internal differences and due to the higher redline of the RS5, uses different transmission control unit (TCU) programming. There is a new longitudinal S-Tronic being manufactured in China for FWD cars. I believe it's called the DL387 but it doesn't share much with the DL501.

The DL501 is rated at 406ft.lb of holding capacity. Aftermarket TCU tunes allow the transmission to handle more torque. I have the gear ratios and I'll add those here soon.

Like the differential, the DL501 transmission uses two different transmission fluids and has two separate chambers for each fluid. Some DCT's, like the one found in the Nissan R35 GTR, house all of the mechanics, gears, actuators, clutch, in one housing and use two fluids. That expands the fluid requirement by a good amount.

On the DL501, one chamber houses what's called the mechatronics unit along with the wet clutch pack. This is composed of hydraulically-actuated gear selectors along with the electronics to control them. Think of it as a robotic left leg. Fluid in this side of the transmission is referred to as ATF fluid.

The "mechanical" side houses the actual gears as well as the front and rear differentials. Fluid inside this chamber is referred to as MTF fluid.

The genius in this design is it narrows the fluid specification down as one fluid is not required to do all things.

The two fluids used in the transmission are different from the differential despite both having an MTF and ATF side. It's confusing but again, the fluids are specified differently due to different properties needed by the internal components.

Here are two great explanatory videos to watch:

https://youtu.be/MjaCbpw84kw


https://youtu.be/1CRzHvTW0dI

Servicing the DL-501 S-Tronic Transmission

One more video, this one shows the wet clutch for the DL501 being taken apart. There's some interesting tidbits there and you get an idea of why Audi uses a very specific fluid for the ATF side which services the mechatronic and the wet clutch.

https://youtu.be/oeTrxEirH0Y

Transmission OEM fluid part numbers
ATF: VAG G 052 529 A2 (7 liters)
MTF: VAG G 055 532 A2 (5 liters)

The manual transmission fluid (MTF) or gear side fluid specs aren't well known. I did find specs on a Polish Audi site here: https://www.vw-group.pl/files/MSDS/G__055532.pdf

My polish is a bit rusty but I can glean some specs.

VAG G055 532 Specification
VIS @ 212F=8.0
VIS @104F=40.0
Viscosity Index=?
Pour Point -?
Flash Point 392F

It lists G055532 but not the "A2" part. It is not a thick oil to say the least so I've decided, based on the specs I've found for other supposedly compatible oils, to stick with the OEM fluid. I very much wanted to use the Motul Gear 300 but I cannot guarantee it'll play nice with the front or center differential. I'm not sure if it has the right additives package.

The specifications for the ATF side, G 052 529 A2 are apparently known by many oil manufacturers and there's a wide selection of fluids available which meet this specification. Some of these "DCT" fluids actually meet BOTH gearbox specifications, that for the ATF side as well as the MTF side. Motul Multi-DCTF is a great example of this. I'm steering clear of those fluids and here's why; as mentioned before, Audi created two different specifications which most likely perform better in their respective environments than a do-it-all fluid. The ATF side of the transmission isn't exposed to gear shearing like the MTF side and likely needs a thinner fluid to heat up and cool down more quickly. It's operating hydraulic actuators and maintaining the proper friction ratio for the wet clutch packs, similar to a motorcycle oil that not only lubes the engine, but the transmission and clutch too. It's also in charge of cooling down the Mechatronic electronics controller which is internal. Early DL501 transmissions often failed when the electronics board burned out (Pre-2012). The electronics board itself is now a serviceable item and can be bought and installed separately.

Here's a full list of all of the "ATF" fluids which meet G 052 529 A2 specifications:

Redline DCTF 100% synthetic (Lists G 052 529) https://www.redlineoil.com/Content/files/tech/DCTF_PROD_INFO.pdf
VIS @ 212F=8.1
VIS @104F=40.7
Viscosity Index=177
Pour Point -50F
Flash Point ?

Motul Multi-DCTF Semi-Synthetic blend https://s3-eu-west-1.amazonaws.com/m...pdf?1510939252
VIS@212F=7.3
VIS@104F=33.8
Viscosity Index=189
Pour Point -49
Flash Point 385F

Rowe ATF DCT II Full synthetic
Viscosity @ 104F 32.8
Viscosity @ 212F 6.6
Viscosity Index 175
Flash point 366.8F
Pour point -40

Ams oil DCT Fluid 100% synthetic (meets G 052 529) https://www.amsoil.com/lit/databulletins/g3431.pdf
Amsoil
VIS @ 104F=38.8
VIS @212F=7.7
Viscosity Index=177
Flash point=446F
Pour Point -72.4

Pentosin FFL-4 ***Not confirmed to work with the S-Tronic yet*** http://www.pentosin.net/specsheets/pentosin_ffl-4.pdf
Viscosity at 104F 36.3
Viscosity at 212F 7.0
Viscosity Index 173
Pour Point -51C/-59.8F
Flash Point 224C/435.2F
***A note on Pentosin products. If you do some research, you'll see they recommend their FFL-2 for the S-Tronic. Well, that's NOT for the DL501 but rather the new FWD S-tronic DL387 which has a far lower torque rating.***

Liqui-Molly 8100 DCT Fully synthetic (meets G 052 529 A2) https://pim.liqui-moly.de/pidoc/P000...00-31.0-us.pdf
Viscosity @ 104F 33.0
Viscosity @ 212F 6.85
Viscosity Index 174
Flash Point 392F
Pour Point -54F

Castrol Transmax Dual Full synthetic https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/8CA4D9C7A952E6C98025803C004AFC36/$File/BPXE-AEX992.pdf
Viscosity @ 104F 35.5
Viscosity @ 212F 7.2
Viscosity Index 166
Flash Point 446F
Pour Point -97F

Millers Millermatic ATF DCT-DSG Full synthetic https://www.google.com/url?sa=t&rct=...Kr-npFR_9Na03X
Viscosity @ 104F
Viscosity @ 212F
Viscosity Index 1
Flash Point
Pour Point

Torco DCT 100% synthetic
Viscosity @ 104F 7.0
Viscosity @ 212F 33.9
Viscosity Index ???
Flash Point -54C
Pour Point 383F

Dodson Motorsports DMS Euro
This is a company out of Australia which does a lot of DSG work on various cars from the Lamborghini's S-Tronic to Evo's to R35 GTR's to Porsche, Audi and VW. They list no specifications on their web page and didn't really give any up to me when asked although they were helpful in other regards and said if we start breaking transmissions, they'll make them stronger. They are looking at uprated clutch packs now.
https://www.dodsonmotorsport.com/audi/fluids/heavy-duty-transmission-fluid.html
Interestingly, they list their fluid operating temperature range between 70-90 celsius. The RS5 typically sits at about 101 degrees celsius. There's also a nice little chart on their page which lists the specs for clutch grip, gear lubrication and longevity for their various fluids. They have three GT-R fluids and it's interesting to see the tradeoff (albeit really simplified) between them.

So now that you've picked the fluid you're going to use (or pulled your hair out), here's a full parts list of what you'll need for the ATF side. It does pay to shop around. One place may have all the hard parts but charges $5 more a liter for the fluid. So look around and find the best deal you can. I do always try to support the Audi performance sites that support us, especially when they have a good web page and answer questions. I'll pay a bit more even. But no communication, no sales. And quite frankly, some of the websites are really poor from an e-commerce standpoint. Others are huge but have inaccurate or incomplete information. So do your homework!

Transmission ATF Parts List (or what I purchased and cost!)
(7)Liqui Moly 8100 DCT Fluid- $13ea, $91 total with free shipping
(15)Transmission ATF pan bolts, part number N91096801 (M6x20), $1 each, $15 total.
(4) Subframe crossbrace Hex head bolts Mfg. # N91151101 $3.70ea., $14.80 total
(2) Subframe Torx head bolts Mfg. # WHT005372 $4.99ea $10.80 total (Note, a washer is sold separately but they threw them in. Can probably reuse those.)

For the following, I purchased it as a "kit" through ECS Tuning but had to do a small work-around to qualify for free shipping. These are the OEM part numbers.
(1) External Transmission filter gasket (o-ring) Mfg # WHT003379
(1) External Transmission coolant circuit filter Mfg. # 0B5325330A
(1) Internal DSG Filter, Mfg. # 0B5325429E
(1) Pan gasket Mfg# 0B5321371F
(1) ATF Drain Plug Mfg. # N0138157
(1) ATF Drain Plug Washer Mfg. # N0138275

I chose to purchase one of the ECS kits which use OEM quality but aftermarket filters and components but I had to purchase the kit that does not include the external filter and 0-ring gasket. That I had to purchase separately. The kit which comes with all of those components isn't listed as qualifying for free shipping even though it contains the same exact external filter. I'm sure it's just an ECS glitch.
Kit: https://www.ecstuning.com/b-assembled-by-ecs-parts/dsg-automatic-transmission-service-kit-without-fluid/0b5325429ektkt2/
External Filter: https://www.ecstuning.com/b-hamburg-tech-parts/dsg-transmission-cooling-filter/0b5325330a~ham/

ECS throws in their magnetic plug even though the pan itself already has two giant magnets.

(1) ECS ATF Filter/Gasket kit ECS # ES#3200790 $73.99
(1) Hamberg Tech external filter ECS # ES#2972736 $12.31

That'll give you the other "kit" ECS sells which for some reason, doesn't include free shipping, even though it's exactly the same.

MTF Side Parts List
(5) VAG G 055 532 A2 (That's five liters)

Here's a photo of everything needed to service the transmission and rear differential.
https://i.postimg.cc/L6y6FFGp/AD243-EFF-F471-4-DE3-ADF0-3-E7969-E64-CD6.jpg (https://postimg.cc/CzqVbXFP)

Next post, rear differential how to.

Ape Factory
11-03-2018, 07:36 PM
REAR DIFFERENTIAL FULL SERVICE DYI

The rear differential fluid change procedure in a nutshell is removing two fill plugs, two drain plugs, installing new plugs in all four positions and filling each chamber with the right fluid. From a no detail point of view, it's pretty easy.

On a difficulty scale, Id rate this as a 4 out of 10. The two most important steps are avoiding cross-contamination and getting the car level. If you remove those two, it's a difficulty of 2 out of 10, easier than changing your oil.

***Keep this in mind: both of the ATF fill and drain plugs are located on the Drivers side of the differential and the ATF fill plug actually says ATF below it. The MTF plugs are located on the passengers side. Both were marked with blue dye.

ATF-Driver's Side
MTF-Passenger's Side

Repeat this several times in your head so there's no confusion. Screw this up and it'll ruin a very expensive differential.

Tools needed
3/8 or even 1/4 ratchet, short extension and universal joint swivel.
5mm allen socket
Small torque wrench that can spec torque down to 15Nm
A catch container for the used fluid
1L measuring container (this was my catch container)
A fluid pump of your choosing
A few large containers of denatured alcohol
Four jack stands
A low-profile jack
A rubber frame weld puck to use as a jacking point
Paper towels
Latex gloves

https://i.postimg.cc/028wnZd6/F6-B1-BCFA-5525-44-B2-938-E-E49-E14979-B77.jpg (https://postimg.cc/V5VvLqh1)

Photo of the fluids needed. The two small containers on the right have used fluid in them.
https://i.postimg.cc/jq6fyBN0/952-B1264-6957-4-AD6-8-EC7-6-B0-CC0-F9-D045.jpg (https://postimg.cc/c6H6S9XX)

Tips!
-The ATF-side fluid is very thin and easy to pump. The MTF gear oil side is thicker but you only need to pump less than one liter and it's still fairly easy to pump. With that said, double up your fluid pumps. Just get a cheapo pump like this from Amazon: https://www.amazon.com/dp/B000BQW5LK/ref=sxts_kp_bs_1?pf_rd_m=ATVPDKIKX0DER&pf_rd_p=8778bc68-27e7-403f-8460-de48b6e788fb&pd_rd_wg=Yg9XR&pf_rd_r=RZS4G08912WCF00QER3A&pf_rd_s=desktop-sx-top-slot&pf_rd_t=301&pd_rd_i=B000BQW5LK&pd_rd_w=IW8tj&pf_rd_i=fluid+pump&pd_rd_r=227873e7-91ef-4d96-b448-a8c73d3afc67&ie=UTF8&qid=1541987852&sr=1

But get TWO. Why? Fluid contamination is a real thing. The pumps are cheap and you wont have to spend time flushing the pump out with denatured alcohol. Itll really speed up the process.

The fill port is .375 or 3/8. Its relatively small. Make sure you have a fill tube thatll fit into the port.

ATF Side
Torque Specifications
Inspection Plug 15Nm
Drain Plug 15Nm
Use new plugs for both the drain and inspection port.

ATF Fluid Temperature between 50F and 140F when filling.

https://i.postimg.cc/RZQmCQnB/F500-C746-35-DB-4119-8171-120-C6-F214670.jpg (https://postimg.cc/RWFyXtRs)

https://i.postimg.cc/wB8k2LW7/6107-EAC0-D199-48-DA-ABA2-8357-E36-CF6-A1.jpg (https://postimg.cc/v4h9Hgws)

Blow by Blow Steps
-Jack the car up at all four corners and make sure the car is level front to back and side to side. I used a long bubble level, about 4ft., to check. A lift makes it far easier to get the car level. If you do not have a long bubble level, you can measure from the concrete to the jack position on all four corners.

-On the driver's side of the differential, look for the drain (on the bottom) and inspection/fill plugs (on the side above the ATF designation).
https://i.postimg.cc/Kz4h56pG/DA17-B17-D-CD9-C-45-C9-AEC1-3-A95-BDAEBB12.jpg (https://postimg.cc/bDX5yBjW)

-Remove the ATF inspection plug first using a 5mm allen socket. This way, if you cannot get the inspection plug out, you can still drive the car to the dealer and have them remove it. Honestly, it shouldnt be difficult to loosen as theyre not on there tight.
Here's a closeup. It's right above the "ATF" symbol.
https://i.postimg.cc/L5j3PXpr/22438943-E1-C0-4561-AEAD-3-C635-E6-E3431.jpg (https://postimg.cc/BPQF9Jtg)

-Make sure your collection container is in place. Remove the ATF drain plug using a 5mm allen socket and allow fluid to drain into the container.

-Install new ATF drain plug and torque to 15Nm. It was a tight fit but I was able to get my torque wrench in there. The exhaust pipes create interference.

-Fill with new ATF fluid through the inspection port opening until fluid begins to drip out a bit. Let the fluid settle for a few minutes then continue to pump in fluid slowly until it starts to run out the inspection/fill hole again. I physically measured the fluid that drained out and filled it with the same amount. Waiting for the fluid to settle allowed me to get the full amount in.

-Install the inspection plug hand tight. From here on out, its a bit different from what I did.

Heres what Audi will do next. The sport differential needs to be primed after a refill. The Ross-Tech VCDS cable/program does NOT have the capability to prime the active differential pump, hence the reason I measured the fluid drained and the fluid pumped back in. But read on.
-Connect the diagnostics module to the car and turn the ignition on.
-Select 22-AWD Electronics in the vehicle diagnostic tester under Guided Functions in the directory.
-Follow the instructions given by the vehicle diagnostics tester exactly.
-Repeat the filling process if the system detects there is still air inside the system after performing the 22-ATF Filling function.
-Remove the ATF check plug again (should only be hand tight!)
-If necessary fill the ATF and run diagnostic function again.
-Install the new ATF inspection plug and torque to spec.


If you do not measure the amount of fluid drained and filled, the car will need to be lowered off the lift and driven for a bit to cycle the electronic differential pump, prime the system and purge the air to the top. Once thats done, place the car back on lifts, level again, remove the inspection port on the ATF side and add fluid if none drains out of the inspection plug.

Gear Oil Side
-Inspection/fill plug torque specification is 15Nm
-Drain Plug torque specification is 15Nm
-OIL Fill TEMP 50F to 140F
Use new plugs for both the drain and inspection port.

-Remove gear oil check plug first
https://i.postimg.cc/q7vv9ZDY/7-C0-A32-CB-4640-48-AD-90-B3-8-DB9-D1-D49-E44.jpg (https://postimg.cc/pm3vjkHY)

-Remove the gear oil drain plug and drain differential gear oil into your collection container
https://i.postimg.cc/wTF3xmyn/51764171-1846-49-AF-8-C96-762-C05-CA0-C7-C.jpg (https://postimg.cc/fJtMBkvv)

-Install new drain plug and torque to specification. It's tight on the gear oil MTF side so I had to use a universal joint swivel and an extension

-Fill the differential with gear oil until it begins to drip out the inspection hole. The car must be level for this. When fluid starts to dribble out, install the new inspection/fill plug and torque to specification.

-Wipe off any excess fluid and wipe down with denatured alcohol and a paper towel or rag.

Notes
-Drained fluid on the ATF side came in at 650ml. When I opened the ATF inspection port for the first time, fluid leaked out.
-ATF fill came in at approximately 650ml.
-The Audi ATF differential fluid container is 850ml so not much wiggle room.

-Drained fluid MTF side came in at 760ml. When I opened the inspection port, no fluid came out.
-MTF fill came in at a bit less than 900ml.

Both the drained MTF and the ATF definitely looked used. They were not clear and very opaque in the measuring container, the color of coffee. Id be really interested to see what the ATF side looks like on a car like the S4 or S5 where its a 100K drain interval. Ive saved samples of both and will send them out soon for analysis.

Used ATF fluid after draining
https://i.postimg.cc/Jh9XQLPm/FC8076-E9-8953-49-BB-A892-A2-D2-D0237-F1-A.jpg (https://postimg.cc/DWPm2R9Y)

Used MTF fluid after draining
https://i.postimg.cc/yxKSwyMb/484-C5-A6-C-A350-40-C9-9-CE3-84-B03-E49-C6-BD.jpg (https://postimg.cc/ftHLdmTc)

https://i.postimg.cc/LXL1CbbP/19-AAF66-D-0281-4-B32-9698-58-CA171-E223-E.jpg (https://postimg.cc/ftWykBZW)

Here are the old drain/fill plugs. Note the integrated copper washer.
https://i.postimg.cc/Kj5gFgFv/2-C45-EE4-A-F8-CE-4393-98-D1-0-E75-AA1219-E2.jpg (https://postimg.cc/JHGh50G9)

In the process of editing the video but honestly, it's really not needed as it's a simple job. Will be doing the transmission in the morning.

Ape Factory
11-03-2018, 09:21 PM
TRANSMISSION DIY Goes here

Ape Factory
11-04-2018, 06:23 AM
STILL A WORK IN PROGRESS. I'll remove this notice when it's complete.

The how-to video is now complete! It does not have every last detail that I've listed below so use it as a supplement. It's long, about 20 minutes.

https://youtu.be/EPdEquH8sXg

A couple of quick notes. First, the transmission fluid while still dark, looked far better overall than the differential fluid.

If you're doing both sides of the gearbox on the same day (and into the night), do the manual gearbox fluid FIRST then do the ATF. I'll explain why later in the post.

If you're doing this on jacks, and not a lift, I would use measuring containers, especially for the MTF side as it'll make filling the MTF side easier and you'll know you have the proper amount of fluid in there.

You can shim in between the jack and the frame rail with cardboard. I was able to get measurements within 1mm of one and other this way.

Transmission Torque Specifications
-ATF Housing/Pan bolts 10Nm
-ATF Drain Plug 45Nm
-ATF Fill and Check Plug 45Nm
-Transmission Fluid (MTF) Fill and Check Plug 45Nm
-Transmission Fluid (MTF) Drain Plug 45Nm
-ATF external filter cover 8Nm (depends on type)


Subframe Brace Torque Specifications
-Hex bolts-90Nm + 135 degree turn (66.3 ft. lb)
Triple Square bolts 90Nm + 90 degree turn (66.3 ft.lb.)

TOOLS LIST
Big bucket to dump fluid covered parts in. Make sure it's clean to start with and something you can throw away
Denatured Alcohol and acetone for cleaning purposes. I purchased two gallons of denatured alcohol.
Paper towels, one ton.
Two tons of latex gloves (yes, its a dirty job)
Two measuring containers, a 1L and a 5L. Can use later to make really big pancakes.
Four jack stands or if youre lucky, an actual lift.
A bubble level
Big ruler (to help with leveling)
A medium-sized cardboard box you can cut up
Absorption mat for any spilled fluid
A crawler or cushioned mat
Good work lights so you can see what youre doing (extremely helpful)
Fluid transfer system of your choice, one each for the MTF and ATF fluid
Clear Vinyl tubing, 4-5ft. in whatever size needed (will depend on your fluid transfer hose/adapter size)
Ratchet set, 1/4 to 1/2 as needed
Long breaker bar for subframe brace bolt installation
Torque wrench (torque specifications run from 10Nm to 90Nm. Make sure you can cover the spread)
10mm Allen socket
M8 Triple Square socket
M14 Triple Square socket
7mm hex socket short
8mm hex socket short
10mm hex socket short
17mm hex socket short
18mm hex socket short
26mm hex socket short
T25 Torx bit
T27 Torx bit
T30 Torx bit


Step One-Under Tray and Center Differential Cooling Duct Removal
Get the car up and level on all four corners, front to back and side to side. I used cardboard as shims between the frame pinch weld and the jack stand heads to make minor adjustments. I also chose to remove both front wheels to give me a bit more working room. Up to you but it does help if youre crawling underneath the car.

Now that the car is up, we'll need to expose the bottom of the car. Youll be removing the undertray/splash shied as well as the center differential cooling duct which bolts to the transmission mount/cross member.

A little tip, DO NOT use power tools to loosen any of the bolts. Theyre easily stripped, especially the triple square bolts and a pain to saw or grind off the ends. Just loosen by hand and then use your power tool of choice to get them off quickly thereafter. Same goes for putting them back on. Torque them down by hand. I didnt go by the torque settings, I just make sure theyre snug.

Splash Shield Removal
All told I had 30 fasteners which needed removing. Im missing a few inside the fender so Im sure the total is probably closer to 32 or 33.

List of all the bolts requiring removal
(6)7mm hex head bolts in the wheel wells (3 in each)
(5)M8 triple squares. I think theres supposed to be six, towards the center/back of the shield. Ive always had five but it looks like theres a hole for one more.
(2) T25 Dzus quick release screws
(4)T27 coarse thread screws
(4) T25 screws, non-magnetic
(6) T30 screws

If I remember correctly the Dzus connectors are on the passenger side and hold a duct mouth that looks like it goes to cool the engine block mounted oil cooler. Anywayits held on by two screws. Youll see the mouth of the duct and two torx screw heads on either side of the mouth. If you forget to remove them and pull the duct out, no worries, you can push the duct back in and it snaps into place with a bit of patience.
https://i.postimg.cc/QxPxt2kr/E65606-E5-1-FCD-4-E22-A89-C-1-D5703869-ACE.jpg (https://postimg.cc/6yrNb1mH)

Five of the M8 triple square bolts towards the back, center part of the under tray. These'll strip out if you use a power tool to remove them. Ask me how I know.
https://i.postimg.cc/902DgGSQ/0-E31-CF0-D-ABBE-44-B8-94-F5-52-FB384-DA94-C.jpg (https://postimg.cc/G8M3HsdW)

Six of the T27 coarse thread screws that go towards the leading edge of the under tray nearest the nose.
https://i.postimg.cc/d0Rq5LMq/3280-BA96-3-FEC-4586-9-DC2-6080-CEED7-DFC.jpg (https://postimg.cc/LqXKX467)

Other than that, its very straightforward and easy to figure out which bolts dont need removing. The whole pan will slide towards the back of the car and drop out. Its a big piece, a little heavy and a little ungainly but it'll come out as one unit.

Center Differential Cooling Duct
The center differential cooling duct is bolted to the bottom of the transmission. Its just five T25 torx head bolts. Undo the bolts and itll drop right out. Super easy.
<a href='https://postimg.cc/yWtpj8n0' target='_blank'><img src='https://i.postimg.cc/yWtpj8n0/Center-Diff-Cooling-Duct.jpg' border='0' alt='Center-Diff-Cooling-Duct'/></a>

Locating the Drain Plugs
With everything exposed, its time to find the correct fill and drain plugs. Depending on year to year variation, all four plugs (two drain, two inspection/fill) are identical. All are the exact same size in terms of plug diameter and thread pitch and all need a 10mm allen socket to remove them.
https://i.postimg.cc/zGMY2J3t/Transmission-Drain-Plugs.jpg (https://postimg.cc/FYj67Xy3)

I have one variation which other cars may not have, the temperature sensor for the manual portion of the transmission doubles as the drain. Its just aft of the ATF pan, dead center, and in front of the transmission mount. It has an electrical connector and is hex shaped. The connector comes off easily by sliding a small white lock down towards the ground. Once thats extended out, you can pull the connector off easily. Only do this when the engine is off and make sure it's plugged back in before turning the car on again otherwise it'll store a fault code. Also, avoid getting any transmission fluid on the outside of the connector or the plug itself. If you get any on it, clean it off right away.
https://i.postimg.cc/ZnWMgdyX/A1-AFD1-B7-468-B-44-EA-BA14-214-FBAEA104-A.jpg (https://postimg.cc/tnHkn7kz)

Here's the MTF inspection/fill plug. It's a bit hard to see looking up. Front of the car is on the left, rear on the right. Looking up.
https://i.postimg.cc/jShYyy6h/B2-C39-C1-C-01-CA-4-B38-B27-B-39-B16-E92-CBD4.jpg (https://postimg.cc/LJhWpYbq)

Its important to change the MTF fluid first as to properly fill the ATF side, the car must be running. Best to have oil circulating (100% necessary) in the mechanical gearbox side while the car is running as you do have to put the car into gear.

Closeup of the transmission plugs. They all use an aluminum washer and in my opinion, all can be reused so no need to purchase new ones. I purchased new ones anyway along with new washers.
https://i.postimg.cc/FFnRLXFK/92785-F64-32-A3-4-ED2-8064-79831-A55-EEF6.jpg (https://postimg.cc/qgy0PY3f)


MTF Inspection/Fill Plug Location-Drivers side, rear of the transmission, above the cross brace.
The drain plug on mine was located on the drivers side rear of the transmission. Its slightly in front of the center differential and its a bit hard to spot due to the transmission brace being in the way. You do not have to remove the brace! But it is a tight fit and youll need to find the best body position to get your hand up there quickly to put the fill plug back in.

Here's the MTF inspection/fill plug. It's a bit hard to see looking up. Front of the car is on the left, rear on the right. Looking up.
https://i.postimg.cc/jShYyy6h/B2-C39-C1-C-01-CA-4-B38-B27-B-39-B16-E92-CBD4.jpg (https://postimg.cc/LJhWpYbq)

The ATF drain plug is on the black pan on the bottom of the transmission. Hard to miss but dont confuse it with the oil pan! The ATF drain plug is an M10 allen head, quite different from the 14mm hex head oil drain plug.
https://i.postimg.cc/vmWZw1J2/ATF-Pan.jpg (https://postimages.org/)

The ATF inspection/fill plug is located on the drivers side and is easily visible just behind the external transmission cooling circuit filter housing. Itll look just like the drain plug (10mm allen head).
https://i.postimg.cc/pXGDr64Q/2-B96-A644-7212-42-A9-9-D17-7-F81-E166-E7-E8.jpg (https://postimg.cc/hfmJ3pSh)




Cliff Notes Blow By Blow

-Remove the noise insulation/splash shields from the underside of the vehicle
-Remove the wire on the cross brace which is held in by small clips. I was able to push the clips out with my fingers.
-Remove the six bolts (four hex head and two Triple Square head) securing the subframe cross brace to the chassis. The cross brace has some weight so be prepared to support it and lower it to the ground.

MTF Side
Drain plug torque specification is 45Nm
Fill Plug torque specification is 45Nm
My drain plug doubled as a temperature sensor and was depicted wrong in any of the workshop manuals. Comes off easily and very accessible but it is a 26mm socket (short is fine) so make sure you have one of those before starting.

-Make sure the new gear oil is at about 68 degrees F, room temperature
-Slide the used oil collection unit underneath the gearbox drain which is located just aft of the ATF pan.
-Place a cloth over the tunnel cross member to keep oil from getting into the cast pockets when the fill/inspection plug is removed.
-Remove the transmission fluid level inspection plug first. Fluid may come out of the inspection port so be prepared.
-Remove the transmission drain plug and drain the fluid into a container.
-Install a new transmission drain plug and torque to specification or reinstall the temperature sensor.
-Fill with new transmission fluid until it begins to run out of the hole and let it sit for at least 15 minutes so the fluid settles internally.
-From then, add 50ml every 15 seconds until the transmission is full. The MTF must be up to the lower edge of the check/fill hole.
-Tighten the fill plug to specification (45Nm)

ATF Side
-Loosen the ATF fill/inspection plug with a 10mm allen socket. Fluid will drain out so be prepared to catch it with a container.
-Carefully loosen the ATF drain plug with the 10mm allen socket and drain the fluid into a container. Reinstall the drain plug, hand snug.
-With the fluid drained, Diagonally loosen the bolts 1-15 on the ATF pan with a hand tool using the T30 torx bit.
-Remove the ATF pan noting there may be more fluid in the bottom of the pan so carefully balance the pan as to not spill the fluid. The pan may take a bit of effort to remove and the internal ATF filter may fall off as well so be prepared. My pan came off with no effort.
-Remove the internal ATF filter by pulling down and towards the rear of the car at the same time. Again, it's filled with fluid and will spill out. Be prepared to catch the fluid.
-Remove the external ATF cooling circuit filter next. If equipped, loosen the securing strap and remove the anti-twist mechanism. Place a collection container below the filter as fluid will drain out when the cap is removed. I had a self-locking cover that has notches to keep it from spinning off. More fluid will drain from the housing.
-With the cap off, pull forward to remove the ATF filter, then slide it behind the two hoses and remove from the vehicle. More fluid will drain.
-When installing the ATF filter, it must not come in contact with water. Even the smallest amount can cause damage to the filter so wear gloves.
-Coat the seal on the end of the atf filter with a bit of atf fluid and reinsert in the housing, with the protruding end going in first.
-Install the cover by screwing it on by hand.
-Tighten to 8Nm. If you have the self-locking cover, tighten it until it's at the last locking notch.
-With the pan on a work bench, clean off the mating surfaces on the pan as well as the magnets (2) and wipe out the entire pan. I used acetone on the pan's mating lip, then denatured alcohol. Do the same for the bottom mating surface on the transmission.
-Install the gasket on the pan with the nubs facing down. The nubs will lock the gasket in place.
-Install the new internal filter, cleaning the recess that accepts the end of the filter nozzle so theres no ATF fluid in the recess where the tip of the nozzle goes. This will allow the filter to stay in place. Note the indexing pin on the top of the filter and make sure its fully seated. Move it around so you understand when it is and is not fully seated.
-Install the transmission pan and tighten the new bolts to 10Nm in a cross pattern.
-Fill with new ATF fluid until it just starts to dribble out the inspection port. Install the inspection/fill port plug by hand.
-After filling the ATF transmission fluid, the fluid level should be checked. Using the VCDS, display the ATF fluid temperature. It should be no higher than 86 F at start of test.
-Start the engine with the selector level in P. While pressing the brake pedal, vehicle idling, shift through all the selector level positions, holding each position for at least 2 seconds. P-R-N-D-S. Move back to N then to P and run engine at idle.
-When the temperature reaches 86F, unscrew the ATF inspection plug. If no fluid drips out, add more fluid.
-The ATF inspection plug MUST be closed again by 122F.
-Tighten the inspection plug to specification (45Nm).

Once you start the engine, fluid is pumped throughout the transmission and the fluid level in the pan diminishes significantly which is why you're able to put more fluid in the transmission.

-Re-install the subframe brace and torque all six bolts to specification. The initial torque setting is easy but the additional rotation degrees took some effort and I used a long breaker bar to accomplish that task.
-Reinstall the splash shield/sound insulation.
-Breathe sigh of relief that you're finally done and won't have to do it again for another 20,000 miles (or two years, whichever comes first!).

Dubzz24
11-05-2018, 10:25 AM
This is great, thanks for your contributions! I'm also coming up on 50k miles and am also planning on changing all the drivetrain fluids so this is a big help. I look forward to your updates.

Ape Factory
11-05-2018, 12:28 PM
At Audi now picking up the MTF for the gearbox along with a drain and fill plug. The gear oil cane out to $16 a liter and change thanks to my Audi Club discount. Drain and fill plugs are back-ordered til Wednesday and theyre pricey. Ill cross reference the part number via ECS and see if they can be had for less. Two were almost $18 and they have an integrated washer. I hate leaks so Im using new everything 😊.

Ape Factory
11-11-2018, 08:31 PM
Updated. Rear differential serviced without issue today.

Ape Factory
11-12-2018, 11:33 PM
Transmission is now serviced. Took me forever and a day, mostly to shooting stills, video and doing both fluids. I need a lift and the body of a 20-year-old. Full details tomorrow as soon as I recover.

Update, drove car for the first time and everything was fine. Shifts like butter. Did a short low speed drive first followed by a highway run. Quiet as a mouse and no engine lights.

BigAngryBananas
11-15-2018, 06:10 PM
-Fill with new transmission fluid until it begins to run out of the hole and let it sit for at least 15 minutes so the fluid settles internally.
-From then, add 50ml every 15 seconds until the transmission is full. The MTF must be up to the lower edge of the check/fill hole.

When the dealership did my MTF change, tech noted that he waited until fluid reached the hole. No mention of waiting for fluid to settle. Makes me wonder if he did or not now...

Ape Factory
11-15-2018, 06:46 PM
Yep, the FSM plainly states to wait a bit after the first dribbles and then do 50ml at a time every 15 seconds til it starts to drip again. I skipped this step too but I measured how much fluid came out. Pretty much caught every last drop with a bit absorbed by the rag on the cross brace. So I added 100ml for that and what was in the filters. I've been driving fairly easy for the past few days and hammered it a bit tonight. Feels good, maybe a tad smoother overall and most importantly, no leaks! The ATF pan bolts are only on there with 10Nm of torque but seems to have worked. I really cleaned the mating surfaces well though. Acetone then rubbing alcohol.

boostinfd
11-16-2018, 10:23 AM
Great post! Thank you!

Ape Factory
11-16-2018, 11:56 AM
Still working on it! Tons more info to flush out along with pics and video. Just a super busy wee with a lot of my staff on vacation so Im pulling up the slack myself.

iiTz-PeRSiaN
11-21-2018, 10:08 PM
How many liters is needed for the OEM MTF for the Transmission?

Ape Factory
11-21-2018, 10:13 PM
How many liters is needed for the OEM MTF for the Transmission?

Five.

Overbias
11-23-2018, 04:53 PM
Thank you for this thread! Amazing info and insights. I am following your lead with parts and specifications. Cross referencing from the service manual as well of course. I am about to do the 75k service and was wondering in which order would you complete, engine oil, transmission and differential servicing?

Its the little items that are so valuable. Like opening the inspection port first to know you can refill before opening the drain port.

Thank you!


Sent from my iPhone using Tapatalk

Ape Factory
11-23-2018, 08:19 PM
The rear differential is pretty easy and I'd just do that first. I would service both sides as the fluid in mine did not look good. Technically, you can't tell a damn thing from looking at it but it looked darker than the transmission fluids. Changing the rear differential fluid is a good way to get your feet wet so to speak.

If you're changing the oil from the bottom, through the drain, then you can just do that when you do the transmission as the under tray has to come out for either. If you're changing it from the top with an extractor, then do that first, then the transmission. If you're doing it from below, I'd still do the oil first. When changing the transmission fluid, do the manual transmission fluid first then the ATF fluid. You do not need to heat the manual transmission fluid up to operating temperature like you do the ATF fluid.

Originally I'd planned on doing the transmission, differential and carbon clean all at the same time, same weekend. Glad I did not do that! It's definitely a two-weekend affair.

I have not sent out my fluids to be tested just yet. I heard I should not send it to Blackstone and there are other labs which are better. I just haven't done that bit of research just yet and I don't want the samples to get lost in the holiday shuffle.

iiTz-PeRSiaN
11-27-2018, 01:10 PM
Fantastic write-up! I'm planning to do the Transmission MTF in a couple weeks.
Just to confirm; if I have a sensor attached to my MTF drain plug, am I just reusing the same drain plug with a new washer?
Also, you mentioned that all drain and inspection plugs for ATF/MTF are the same. When I research the product codes you provided (Mfg# N0138157 & N0138275) it seems they are both washers. Do you have the Mfg# for the Transmission MTF plugs and washers?

Thanks for the instructions!

Ape Factory
11-27-2018, 05:01 PM
Fantastic write-up! I'm planning to do the Transmission MTF in a couple weeks.
Just to confirm; if I have a sensor attached to my MTF drain plug, am I just reusing the same drain plug with a new washer?
Also, you mentioned that all drain and inspection plugs for ATF/MTF are the same. When I research the product codes you provided (Mfg# N0138157 & N0138275) it seems they are both washers. Do you have the Mfg# for the Transmission MTF plugs and washers?

Thanks for the instructions!

The sensor is the drain plug so yes, you'll just reuse the sensor. You can reuse ALL the plugs on the transmission unless you tear them up but it's highly unlikely as they're pretty solid. The washer can simply be replaced. I reused a few and I crawled under my car today to check for leaks. None.

But the OEM washer is part number N0138275 (need four if you replace them all) and the plug is part number WHT005282 (need three if you decide to replace those.)

I'll update the thread above with the part numbers. Let me know if there's anything else I missed! Still trying to find time for the videos. :(

Overbias
01-19-2019, 06:40 PM
Thanks for all the great tips! Finally got around to doing the rear diff today. Your advice and detail here was invaluable. I ended up using ramps and jacks with jack stands and while that was just enough clearance for the rear the transmission was a whole different story. I would love to know how much clearance you were working with as it was really difficult to get in there. Decided to complete the rear and leave the transmission for another day but this would be so much easier on a lift!

Ape Factory
01-19-2019, 06:51 PM
MUCH easier on a lift. I basically had all for stands on the second to last notch, so almost as high as they'd go. Not a lot of room to work or to take photos/video, LOL. If I had to guess, I'd say I had about 20" of clearance? I also took the front wheels off which helps tremendously when it comes time to wiggle around under there.

Here's a disturbing photo. Yes, there are indeed four jacks holding the car up.
https://i.postimg.cc/G2fwRpty/83-FF3068-87-DD-4-D37-86-E0-1-FE2973885-B3.jpg (https://postimg.cc/jwykQtzx)

Ape Factory
02-09-2019, 03:15 PM
The video for the transmission service is now done!

I've posted it above in the transmission DIY instructions but here it is again.

https://youtu.be/EPdEquH8sXg

JamesRS5
02-09-2019, 10:16 PM
Well done Michel, great info.

spdemon91
03-31-2019, 12:00 AM
[hail] Absolutely amazing writeup!!! Love the attention to detail and step-by-step. Thank you so much for taking the time to contribute this to the community. You can tell this took a lot of research to put everything together and a bunch of time to document with pictures plus a video. Well done sir!

I have a 2013 S8 and I have been researching how to change the differential fluids. Unfortunately, there is not much information available for my model because the geniuses at Audi claim the fluids are magical and will live happily ever after, forever and ever... [rolleyes], or at least until your car blows up. [facepalm] Doesn't make sense that they call for service on some models but not others even though models share some of the same components. My car has the OBF sport differential which I believe is the same as your car so the write-up for the rear diff I should be able to follow pretty closely. For the transmission however, I am sporting the 8-speed automatic, totally different set-up. Still, your write-up is very useful for all the tips and tricks. I wish someone with an A8 / S8 with 4.0TT generation D4 would do a similar write-up for changing the differential fluids. If anybody has any insight here, I would certainly appreciate it.

One question - I have read other posts on the transmission fluid change which recommend running the car through the gears for 20-30 minutes (or even coming back a week later) and performing a second drain and refill (not dropping the pan of course, just from the plugs). The reason is some components in the transmission do not drain even with dropping the pan. After the new fluid gets mixed properly through all the components, the second drain and refill achieves a fuller refresh. Don't know if this is specific to the 8 speed automatic but since you have done such excellent research, I was curious to get your opinion on the matter.

Ape Factory
03-31-2019, 07:07 AM
Entirely plausible on the second drain and refill. Audi even states that a full refill (if changing out the transmission) requires more oil than a normal maintenance change. Some fluid does get trapped inside the various mechatronic components as well as the transmission cooler and cooler lines. I think it's a bit excessive and probably not needed unless the fluid was severely degraded or there's enough of a difference in the fluids that it's warranted.

As far as the rear differential, I believe they specify the same thing in the S5. As in lifetime fluid. If you go to your Audi dealer, they should be able to tell you what fluids the differential uses. I'd be surprised if they were different from the RS5. I'm willing to bet just about everything is the same. The S6 uses the same rear differential and uses the same DL501 dual clutch transmission as the RS5. I'm actually surprised they don't recommend fluid changes in the S8 as it's much heavier. Maybe they just expect less abuse from someone driving an S8 than an RS5.

Not sure if you have the factory service manual but Audi has each model in PDF format. For a small fee, you can download it and it's yours to keep/print out etc...Comes in handy.
https://erwin.audiusa.com/erwin/showHome.do

spdemon91
03-31-2019, 08:59 AM
Thanks Ape. Regarding 2nd drain, my understanding is the reason for the 2nd drain on the 8 speed automatic transmission anyway is that the fluid in the torque converter does not drain at all. Only after cycling the transmission can these fluids be reached. So the logic is to run through the gears for 20-30 minutes or come back a week later after driving the car to ensure the fluids have properly mixed. The drain/refill to achieve fresher fluids. I would think the 2nd drain after driving the car for a week would also help if any sludge or gunk was freed up by the initial drain/refill. Your transmission is totally different so probably not applicable.

Regarding erwin, yes, I subscribed about 2 months ago and I have been periodically going through everything. Lots of helpful information, especially all the TSBs. When it comes to the drivetrain though, the material is several hundred pages long and spread across two large manuals. The problem is they cover every possible component difference for all variants of the drivetrain for many different models and model years. This makes for a convoluted mess in my opinion. The drivetrain complexity with all the different components of rear, front, hydraulic, center, transfer case, etc. adds even more confusion.

I will persist though because I refuse to go to the dealer and get bent over for fluid changes. I am not a DIYer but like to ensure my cars are taken care of, buy my own fluids/parts, and be able to give relevant procedural information to my general non-Audi-specific mechanic. They also service my Viper but that car is a totally different beast. On my Viper, it could not be any more straight forward and the differential and transmission fluids are changed every 3 years per service manual guidelines. But the Germans at Audi say, "No vorries, vie makes you lifetimes fluid zat never needs changing." Hence, information on the process is limited. Ugghh... [facepalm]

I am trying to stir up the veterans on the A8 D4 board to get some more information. Would love for someone to put together a detailed write-up like you did. I would tell you that you need to sell your car and buy a D4 S8 but your car is sick! [up]

Any further insight would be appreciated.

Ape Factory
04-01-2019, 07:35 AM
It isn't going to hurt to change the diff fluid. Not sure how many miles you have on your S8 but changing it every two to three years might be a good idea. It's fairly easy to do and doesn't take a lot of time. I'd just take a look and see if you have the same drain plug setup as in the photos above. I'm pretty sure you will. You'll just have to go to the Audi parts counter and get them to confirm the fluid. Even though it says lifetime, they'll still have a part numbers for the fluid as they don't ship new differentials already filled. If it's a sport differential like you said, it'll use two different fluids, one for the actual ring/pinion section and one for the clutch pack section. You can just use Motul Gear 300, or whatever your choice of gear oil meeting Audi's criteria is, for the ring/pinion section (MTF). The clutch side (ATF) will have to be an Audi fluid. No one makes a suitable replacement.

As far as the automatic transmission, there are a lot of companies who specific lifetime fluid but ideally, I think it's good to change it every 60K to prolong the life of the transmission. Makes total sense on the torque converter, especially if it holds more than a liter of fluid. I'm sure the valve body retains some fluid as well. If your fluid looks like it's in good shape when they drain it, not burned, you may be able to get away with just the normal drain and fill. I've heard of issues with power flushes so I'd steer away from that. I think some of the issue is when you do change out lifetime fluid, there is the possibility you could gunk up the valve body or converter with loosened deposits. There's lots of fine passageways in both as you know.

Erwin. Yes, it can be a mess as, like you said, they include every specification in the manuals. Most of my erwin manuals also feature info on the A5 and S5 so I have to wade through sections that aren't applicable. I've actually read most of it at this point and I tend to print out the important pages when I'm working on something and keep those in a binder. I can make notes on them that way too. Eventually your brain adapts, LOL. It took some time to fully understand everything as the systems do tend to be more complex from an engineering standpoint and obviously the quattro system adds to that complexity.

spa
04-02-2019, 01:52 PM
Fantastic write ups and videos, you sir are an asset to the RS5 community!

I have been going over my invoices from the dealer comparing the #s to yours and i noticed in the two changes they did the transmission both times they stated (two different dealers too!)
6L of VAG G 052 529 A2
4L of VAG G 055 532 A2

You state 7 and 5L for the job, does it take both those amounts fully? I am wondering and I underfilled or they didn't completely drain my car or not charging my the extra L... hmmm

Now it's off warranty I will be following your guides and DIYing it and knowing for sure... damn dealers.

Ape Factory
04-02-2019, 09:15 PM
The amount I specify is not necessarily the amount you'll put in but it's enough to cover the spread so to speak. You should have a bit left over. Some will use a bit more, some a bit less depending on how much gets drained and how much the initial fill was (either at the dealer or the factory).

The two different part numbers are for either the MTF or ATF fluid. Depending on what service interval you're at, one or both may get changed. And thanks for the compliment!

spa
04-03-2019, 07:07 AM
Thanks for the info. I also noted the inner transmission filter was never replaced as I see no part numbers for that or a new gasket.. I don't think Audi have it as a listed maintenance item? I also see they did the ATF side of the rear diff but no mention of the MTF change on the diff, again I see no mention of the MTF change for diff listed on the maintenance schedule either. Are those two extra things you did even though they aren't officially listed?

Just trying to see if the dealer got lazy or just doing it by the book...

I will do them all regardless going forward.. Thx!!

Ape Factory
04-03-2019, 07:44 AM
What year is your car? Are you in N. America or elsewhere? I know a while back Audi was NOT changing the internal filter but I believe that was on the pre-facelift B8 cars up til 2012. It's since been part of the recommended maintenance for all S-Tronic DL501 transmissions. On the rear differential, it should have been both fluids changed at the same time.

Here's a maintenance schedule for the 2015 model year which is the same for 2013-2015. https://www.audiusa.com/content/dam/audiusa/Documents/maintenance-schedules/MY_2015_Audi_USA_Scheduled_Maintenance_9-7-2017.pdf

If you notice, the RS5 and the RS7 both have the rear differential ATF and gear oil serviced at the same time. In imperial miles, it's at 35/75/115,000 miles. If they did not do both, I'd bring my car back and insist they do the other fluid and make a note they did not do it on time (their fault) in their service records in case your differential suddenly fails. Get it in writing and then document it with Audi national headquarters. Best to do it now when there isn't an issue as everyone will be in a better mood!

Same for the internal ATF side filter on the gearbox. Get it noted in writing.

The MTF side is changed at 15/55/95/135,000 miles.
The ATF side is changed at 35/75/115,000 miles. That includes replacing both the internal and external filter.

Since I'm doing "performance" maintenance, I'll be changing both fluids in the rear diff and gearbox every 20K or every two years. I still need to get the old fluid tested but I'll have the fluids I personally put in there last time tested as well. Just to see where we're at after 20K miles.

I'm also in the process of developing an auxiliary transmission cooler for the ATF side fluid. It'll keep the OEM cooler which does double duty, heating the fluid up to temp quickly and then cooling it when it gets above coolant temps. It's possible to see temperatures in the high 300 degree range and the transmission will go into limp mode usually around 200 celsius. A transmission cooler will help with that greatly and keep everything a bit cooler including the electronics which are cooled by the ATF fluid. It'll offer more consistent performance.

I'm having special adapters machined out of billet aluminum so none of the OEM coolant lines will need to be cut and no external pump will be needed. Plug and play as they say.

spa
04-03-2019, 10:45 AM
I bought my car CPO it's a 2013 and I am in Canada, another dealer did the maintenance under the original owner's watch. Since I owned it I have only done the MTF side of the transmission on schedule so far. Warranty is finished with the car. I have all the old invoices of the car so that's what I am reading over to see what they did or didn't do. Thanks for the input and great idea you got on the extra cooler!

11S5V8
04-03-2019, 02:47 PM
Is this pretty much the same process for the S5? I have an 11' V8 S5 and have been contemplating doing this maintenance as I'm about 100k+ miles as it is.

Ape Factory
04-07-2019, 09:22 PM
Not sure if you have the S-Tronic dual clutch in the 2011 S5? Rear differential, if it's the sports diff, should be similar but I don't have any experience with your model year. I'd check the factory service manual. You can download it through audi. https://erwin.audiusa.com/erwin/showHome.do