DIY: Audi B7 RS4 Rear Differential Oil Change

[BenSti]

Couldn't find a DIY for how to do this so I decided to make my own. Hopefully this helps everyone. Let me know if you need anything clarified.

Audi says it is lifetime fluid, common sense says it isn't. I figure change it every 50k miles and you can't go wrong. Expecially because it uses such little oil. I chose to go with Amsoil Severe Gear 75W-90 because I had good results with it in my Subaru. You could use whatever oil you choose, it needs to be GL-5 rated.

Time: 15 minutes
Cost: $15-$30 depending on the oil you use.
Tools:

• 3/8" Ratchet
• 3/8" Torque Wrench
• 10mm 3/8" drive socket
• Oil Pump

First off, get the back of the car up in the air. It would be best to get the car perfectly level to get every bit out, but I don't think it really matters. The drain plugs is up in the front of the diff so it should get nearly everything out. I like to use ramps because I am lazy.


1. Using the breaker bar and 10mm socket, break the fill plug loose first. It's on the passenger side in front of the axel. It shouldn't be that tight, but make sure the socket is all the way in the plug.




2. Once the fill plug is broken loose, crack the drain plug and drain the oil into a small container. My car drained out 0.8L of fluid.








3. Attach the pump to the bottle of oil and stick the fill hole. Make sure to put back in the drain plug before pumping. Fill with the same amount you drained out.

4. Reinstall the fill plug. Torque the drain plug to 26lb/ft and the fill plug to 13lb/ft.

5. Lower the car, clean up, and you are done!

[V8PWR]

Nice work!

[zachf88]

so, .8 litres?

[NY07RS4]

Technically .9L or 1QT but close enough.

Ben - good job man, you are on a roll with the DIY threads

[BenSti]

Yeah, I think it was probably a little more if you had the car perfectly level. Either way, all you need is one quart to change it.

[dparm]

S4 rear diff is 1.5qt to fill, though we all know you won't get it all out. Buy two bottles and you'll have some for next time. :-)

Also, be careful with the type of container you drain it into: long-term storage in certain types of plastic containers will end poorly.

[BenSti]

Good point with the container. My drain pan was a bulk container of windex which I cut in half. I dumped the oil back into an empty oil bottle to get a measurement. I store my oil in a 25 gallon gas container until it is full at which point I take it up to Jiffy Lube.

[NY07RS4]

S4 rear diff is 1.5qt to fill, though we all know you won't get it all out. Buy two bottles and you'll have some for next time. :-)

Also, be careful with the type of container you drain it into: long-term storage in certain types of plastic containers will end poorly.

Weird, the fluid chart I have from Audi states 1.0QT for both the S4 & RS4. Although, I agree, always buy two to cover yourself.

[SoCalS4Avant]

Great work, Ben. This and your other DIY's have been copied over to the B6/B7 S4/RS4 DIY/Tech forum.

[S4SHOES]

i followed this for my s4 and everything was very similar except:
the fill plug was behind the axle on the passenger side and the i had to remove the axle shield to get to it
axle shield is 3 socket head bolts that use a 6mm

thanks for the write up!

[coasterjob]

Is it a good practice to this while changing the MT fluid? Looking to change MT and Diff this spring.

(Just read Dparm's MTF write up)

[dparm]

The rear diff does not get nearly as much stress as the MTF/center/front diff housing does. You can change it much less frequently.