how EXACTLY does the S4 V8 consume oil?

[emilio]

the BHF's oil consumption is notorious, but it's also surrounded in a decade of speculation and hearsay. it's unclear even how common it is.

oil consumption is usually blamed on cylinder wall scoring, and i've certainly seen streaks on my cylinder walls to jibe with my quart per thousand mile consumption (which has held steady for years, besides a leaky gasket at one point). the oil seems to be going out the exhaust, too, as sooty tailpipes commonly go with increased consumption. however, there is no consensus whatsoever on just what's happening to the oil, how the cylinder walls get damaged in the first place, and certainly not how to fix it.

oil can disappear from engines in three ways:

• it just leaks out, including within the engine (e.g. into coolant).
• it gets burned up in the cylinder and goes out the tailpipe (or cakes up your cats).
• it sludges up and remains in the engine, but is unusable.

cars that don't leak a drop will still consume oil, and our engines don't have significant problems with sludge, so the oil is getting burned up. (i'd love to hear from someone that has excessive oil consumption without sooty tailpipes, as that would be strange.)

so, here are the ways i think BHFs can lose oil with relation to cylinder wall scoring and piston rings (let's put aside how the walls get scored, that's a whole other area of poor information):

• oil remaining in the scoring: the scoring gives a place for excess oil to stick and the oil control ring can't wipe it off the wall, leaving it to be burned at combustion.
• insufficient ring wiping: the scoring is just a symptom of stuck or damaged oil control rings, which leave oil on the walls to be burned. note that this is different from just losing oil to scoring.
• blow-by raising crankcase pressure: damaged cylinder walls or rings allow combustion gases to blow by, raising the crankcase pressure. the increased crankcase pressure triggers frequent or constant PCV recirculation, passing oily crankcase vapors back through the intake manifold to be burned in the cylinder.
• a malfunctioning PCV system that triggers constant crankcase ventilation without ring blow-by.

it's easy to imagine oil left on the cylinder walls burning up. however, i've removed my intake manifold a couple times and have seen some decent sludgy deposits on the runners. you can see when i had the IM off around 88,000mi.

i had it off again recently (around 115,000mi) and there were similar deposits, though not as thick; the inside of the IM also appears oily. i can easily see this level of deposits going along with 1qt/1000mi consumption (that's just what sticks to the walls, imagine what's going in the cylinder). i also have sooty tailpipes, especially on the driver's side. i have treated the pistons with Kreen, which supposedly frees stuck oil control rings, as well as swapped the PCV and suction jet pump, but they didn't seem to change anything.

in the case of my engine, the intake deposits and attempted fixes point to blow-by increasing crankcase pressure. people who install catch cans and stop getting sooty tailpipes probably have the same issue. however, my experience may not be typical and there may be several ways that these cars consume oil.

i have sifted through lots of posts and very, very few reach any sort of conclusion (with or without a fix). so, i still wonder if...

has anyone ever significantly reduced excessive oil consumption (.5qt/1000mi or more) without new rings or sleeving?
(i've heard of less consumption getting fixed with a new PCV, but not more.)

for that matter, has anyone reduced their consumption with new rings or sleeving?

does anyone have excessive oil consumption that does not have sooty tailpipes?

are there any oil-consuming cars with clean intake runners?

has anyone seen a significant and documented reduction in oil consumption from using 5W-40, e.g. Rotella T-6?

has anyone installed a catch can that did not eliminate their sooty tailpipes or sludgy intake runners?

has anyone reduced oil consumption through cylinder honing without new piston rings?

now, i've come to accept my S4's oil consumption as just part of the, erm, "fun" of ownership. however, i would still love to get rid of it without a machine shop!
- emilio

[p3u]

Mine consumes no oil. Always warm it up and cool it down. Run mobile 1 European blend.

[SprintBlueWorld]

You forgot valve seals which could also be a bit of a culprit. Owners have reported black cloud left behind from time to time upon exceleration.

For myself I replaced my OEM PCV with an aftermarket around 50k miles, did the VCGs about 60k and run Motul Xcess 5-40. I see the same pattern as long as I have owned it where the oil level doesn't move for the first 1500-2000 miles after a change. Then it seems to reduce and use maybe up to a qt. Over that next 3000 before I change it again. Not sure how to explain that away, but it's a steady pattern and not bad at all from some ive heard.

[AudiEmpire]

Mine consumes no oil. Always warm it up and cool it down. Run mobile 1 European blend.

X2...

I always wait for the engine to reach operating temperature (10min after the thermostat on the dash reaches it's midpoint) before accelerating hard. In the past I 'consumed' a very minor amount of oil, but since replacing the VCG's and switching to Mobil 1 0w40 I have no noticeable consumption.

I do notice that my car LOVES fresh oil -

Fresh oil = Buttery smooth start-ups
1k-2k = Minor rattle on ~20% of cold starts
2k-3k = Minor rattle on ~50% of cold starts
3k-4k = Rattle on ALL cold starts
4k-5k = CHANGE OIL

Important note... I've averaged ~8K mi/yr the past 3 years. So while 4k might seem crazy, it equates to once every 6 months based on my usage. Plus it gives me a good excuse to get under the car and inspect for any problems/leaks under the belly pan.

[924Carrera]

Mine burns a lot of oil...averaging about a quart every 550 miles. Certainly some of this was leakage, but even after replacing VCG's and valley pan gasket, the consumption continues almost identically and I definitely have sooty tailpipes. I do NOT have the puff of smoke on startup, acceleration, or overrun, which seems to rule out valve stem seals for the most part. In fact, I never see any smoke, nor did a friend who followed me for 120 miles in a different car. My compression numbers are excellent, within new spec, but I could have scoring...I have not borescoped it yet. I will say that my IM was filthy and full of oil when I removed it for the valley pan gasket job.

I have a new PCV valve and suction jet pump. I ran Mobil 1 0W40 for a while, then switched to Rotella T-6 5W40, seeing 0 change or improvement. I am not the car's original owner, so I have no idea how it was treated in the past, but I always let it come to operating temp before exceeding 3000 RPM. Like you, I've come to accept the oil burning as part of the ownership, so long as it doesn't start to get worse or impact the performance/compression, in which case I will probably be looking at a used engine. I used to stress out a lot about it, but after doing so much work to the car, I figure, a shortblock is no big deal...

[xhackerekx]

mine depending how i drive with heavy foot take like 1qt every 1200miles when drive like any other car take like 0.5qt for 3k miles , always use T6 5w40.

[q_dubz]

Mine burns a lot of oil...averaging about a quart every 550 miles. Certainly some of this was leakage, but even after replacing VCG's and valley pan gasket, the consumption continues almost identically and I definitely have sooty tailpipes. I do NOT have the puff of smoke on startup, acceleration, or overrun, which seems to rule out valve stem seals for the most part. In fact, I never see any smoke, nor did a friend who followed me for 120 miles in a different car. My compression numbers are excellent, within new spec, but I could have scoring...I have not borescoped it yet. I will say that my IM was filthy and full of oil when I removed it for the valley pan gasket job.

I have a new PCV valve and suction jet pump. I ran Mobil 1 0W40 for a while, then switched to Rotella T-6 5W40, seeing 0 change or improvement. I am not the car's original owner, so I have no idea how it was treated in the past, but I always let it come to operating temp before exceeding 3000 RPM. Like you, I've come to accept the oil burning as part of the ownership, so long as it doesn't start to get worse or impact the performance/compression, in which case I will probably be looking at a used engine. I used to stress out a lot about it, but after doing so much work to the car, I figure, a shortblock is no big deal...

decelerate from the top of third, then into second and then come to a stop and let it idle and then get back on it. I guarantee you will.

Or better yet just pull your plugs. Lets see the threads and porcelein around the electrode.

[924Carrera]

decelerate from the top of third, then into second and then come to a stop and let it idle and then get back on it. I guarantee you will.

Or better yet just pull your plugs. Lets see the threads and porcelein around the electrode.

Actually just did that a couple weeks ago. This is the worst of the 8.

[emilio]

Mine consumes no oil. Always warm it up and cool it down. Run mobile 1 European blend.

ah, a control case! how many miles on that block? do your tailpipes ever get sooty? have you ever had the intake manifold off, and were there sludgy deposits in the runners?

You forgot valve seals which could also be a bit of a culprit. Owners have reported black cloud left behind from time to time upon exceleration.

For myself I replaced my OEM PCV with an aftermarket around 50k miles, did the VCGs about 60k and run Motul Xcess 5-40. I see the same pattern as long as I have owned it where the oil level doesn't move for the first 1500-2000 miles after a change. Then it seems to reduce and use maybe up to a qt. Over that next 3000 before I change it again. Not sure how to explain that away, but it's a steady pattern and not bad at all from some ive heard.

yes, the valve seals can introduce oil into the cylinders, but i'm looking more at cylinder and crankcase issues rather than the heads. (thankfully, i have no odd puffs of smoke unless Kreen or Seafoam are involved.)

that is an odd oil consumption pattern! how sooty do your tailpipes get over a tank of gas? i wonder if that 5W-40 is juuuust thick enough to avoid getting lost, but then after 2000 miles it's broken down enough.

I always wait for the engine to reach operating temperature (10min after the thermostat on the dash reaches it's midpoint) before accelerating hard. In the past I 'consumed' a very minor amount of oil, but since replacing the VCG's and switching to Mobil 1 0w40 I have no noticeable consumption.

yes, my since i got the car i've done the same thing for cold starts: idle until the revs drop to normal, only 50% throttle and 3k RPM max until the coolant temp is at the 1/4 mark, then 50% throttle and 4k max until the coolant temp has been at the 1/2 mark for several minutes. once the car is warmed up i drive fairly spirited, and often use WOT and shifting near redline to get on the freeway (traffic allowing); i typically cruise on streets at 2000RPM and freeways at 3000-3300RPM.

AudiEmpire, how sooty do your tailpipes get over one tank of gas? have you ever looked inside your intake runners?

while i'm not the original owner (the fourth, actually) at least the oil consumption has been holding steady - i'm not making anything worse. my car has had the valve cover gaskets replaced (documented dealer work from a previous owner) and i recently replaced the valley pan gasket, so my oil is definitely going out the tailpipe.

- emilio

[AudiEmpire]

AudiEmpire, how sooty do your tailpipes get over one tank of gas? have you ever looked inside your intake runners?


- emilio

My tail pipes have very little soot on them. Only time there is any noticeable build up is during the winter when I may go 5-10 tanks without washing the car. I replaced the stock exhaust with a fullback milltek resonated system in the 2nd year of ownership (owned the car and personally put 98% of the miles on it myself, adhering to the 'warm-up' protocol since day 1.)

[roboto_1337]

X2...

I always wait for the engine to reach operating temperature (10min after the thermostat on the dash reaches it's midpoint) before accelerating hard. In the past I 'consumed' a very minor amount of oil, but since replacing the VCG's and switching to Mobil 1 0w40 I have no noticeable consumption.

I do notice that my car LOVES fresh oil -

Fresh oil = Buttery smooth start-ups
1k-2k = Minor rattle on ~20% of cold starts
2k-3k = Minor rattle on ~50% of cold starts
3k-4k = Rattle on ALL cold starts
4k-5k = CHANGE OIL

Important note... I've averaged ~8K mi/yr the past 3 years. So while 4k might seem crazy, it equates to once every 6 months based on my usage. Plus it gives me a good excuse to get under the car and inspect for any problems/leaks under the belly pan.

Good info. My B7 makes some noises on startup that don't equate to chain rattle or flapper problems but this makes sense.

[macattac]

Mine consumes no oil. Always warm it up and cool it down. Run mobile 1 European blend.

Same here....that being said it's a summer play car so I only drive like 2-3000 miles during a season

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[badger.]

I burn/consume/lose quite a bit of oil. However it seems quite inconsistent, but has definitely gotten steadily worse throughout my ownership of over 100k miles.

CAR INFO:
Car stats: 192,500 miles, 2005 S4, Tip, Piggies + timing done @ 164k. Not tuned. Oil has overwhelmingly been 0W-40 Mobil 1.

“RELEVANT” WORK DONE:
New PCV 2x since I’ve owned the car. New oil filter every change.
Compression testing was done at 164k before I did the timing work. Numbers here: (Need to find these, will link later – they were 140-150 on average)
I have not done a leakdown or borescope. Plugs were changed @ timing job… decent coating of oil on threads of most. Cyl8 (lowest compression) was definitely the worst as well… I have a picture somewhere on my home PC, I will look later.

OWNSERSHIP/USAGE:
I've owned 4.5 years, since 85k miles, so I've put on more that 100k miles myself. I would say I drive it easy after startup 90% of the time. When I first got the car I don't think I paid nearly as much attention to warm-up or anything, I really only started after maybe a year of ownership and learning more about the engine, timing, etc.
I daily drive to work: I have 2 miles through a small town to the highway where I go 22 miles, then another 6 or so through another small town/state highway. So basically 70-75 miles a day, over half being highway. I don’t hammer down on the onramp, but I definitely bump the 3k limit every morning and afternoon first starting out the drive.
I do have a slow leak somewhere; pretty sure it is my oil cooler seals. But I don’t think this represents much as it leaves maybe a drop or two on the ground every 9 hours, if that. It might leak a little faster while the car is moving but I don’t think it is bad, judging by the underside of the car. (I have a PS leak I’m going to try and fix this weekend; so it’s been hard to judge how much of each is on the underside of the car.)

CONSUMPTION:
IIRC I usually had to add 1-2 qts between changes (5-7k intervals) at first. Nowadays, I would say my average consumption rate is 1qt every 300-500 miles.
I recently decided to start tracking this much more closely. Off the cuff it seems very inconsistent… I swear sometimes I can burn almost 2qt in 350 miles, while other times I will top it off and will get >1000 miles before I need another 2qt. I have started a excel sheet to track this more exactly.
I drive from KY to MI a lot. One trip is 330 miles one way, another is 550 miles or so one way. I remember some trips I need to add nearly 2 qts after the first 330 miles. On the other hand, I’ve turned around, driven that 330 miles home, and gotten another 400mi+ before adding any oil.
This most recent time I added some 5W-40 Valvoline (not complete change). This seems to have been helping so far, but no real step change.

SOOT:
Tailpipes/rear of car get sooty pretty quickly these days. It’s annoying since I have a white car.

INTAKE MANIFOLD:
I’ve had it open twice, I think 2 and 3 years ago. I believe there was a decent amount of oil coating the runners – it definitely wasn’t dry. When I had it split and sitting upside down for a few hours, I bet there was 1-2 Tbsp pooled in there before I cleaned.

SMOKE:
Just this week I noticed the worst smoke from the tailpipes I’ve ever seen. Car had been driven (highway) for 35 miles, then parked for 1.5hours, then when I first started it up got a nice cloud of smoke. – Does this indicate valve stem seals?

I have not noticed it really on accel or decel but it is hard to tell when I am driving.


CONCLUSION:
I am guessing valve stem seals are my worst culprit? Oil cooler leak is small contributor. I would not be surprised at all if I have cylinder scoring of varying degrees as well. Car still runs great. A 5qt jug of oil a month is still cheaper than a new engine lol (I drive a lot if you haven’t noticed). If anyone has specific questions or wants me to look @ or track something specific just let me know…

[ngood1]

I have put about 1000 miles on my s4 since buying it one month ago. I added 1 quart to bring the level up. Dealer said the car had a fresh oil change but I really dont think it did. The oil is filthy.

There isn't any visible oil in the engine bay. This weekend I am changing the check oil valves and I will inspect the manifold. I'll change the oil with 0w-40

Is there a way to see if the PCV Valve is working? I'll check that too.

[alcatranz518]

X2...

I always wait for the engine to reach operating temperature (10min after the thermostat on the dash reaches it's midpoint) before accelerating hard. In the past I 'consumed' a very minor amount of oil, but since replacing the VCG's and switching to Mobil 1 0w40 I have no noticeable consumption.

I do notice that my car LOVES fresh oil -

Fresh oil = Buttery smooth start-ups
1k-2k = Minor rattle on ~20% of cold starts
2k-3k = Minor rattle on ~50% of cold starts
3k-4k = Rattle on ALL cold starts
4k-5k = CHANGE OIL

Important note... I've averaged ~8K mi/yr the past 3 years. So while 4k might seem crazy, it equates to once every 6 months based on my usage. Plus it gives me a good excuse to get under the car and inspect for any problems/leaks under the belly pan.

SAME Here, however I change my oil in the 7k mile interval range, run only Mobil 1 Euro synthetic, and she's my daily that I drive quite spirited.