[s-cars] Transmission and Rear Diff. fluid

[Wayne Dohnal]

I changed the oils a few months ago.  Here's everything I can remember!

The car had 130K miles, and the old oil was pretty nasty looking and
smelling, especially the transmission.  So I think it was a good idea to
replace it.  I struggled with what oils to use, and agonized over not being
able to get the Audi mystery additive for the transmission.  After a lot of
input from the list I ended up using Redline MT-90 in the transmission, and
Redline GL5 75W90 in the rear diff.  Everything is still working fine, and I
think the shifting got a tiny bit smoother.

Each unit has 2 drain plugs.  For the transmission you need a 10mm hex bit,
and for the rear a 17mm bit or wrench.  The standard "make sure you can
loosen the fill plug before draining" advice applies.  I found it easiest to
access the transmission fill plug through the left front wheel well (with
wheel removed) and a lot of extensions, but others do it from under the car.
You will drip oil on the cats when you pull the rear transaxle plug.  You
have to remove a plastic shroud under the car to get at one of the rear end
plugs.

The transmission plugs take a lot of torque to break loose, then they go
with a vengeance.  Make sure your hands aren't going to collide with
anything when they break loose.  And don't use Mickey-Mouse tools.  I
twisted a no-name 3/8 extension into 2 pieces trying to loosen one of the
plugs.  On the transmission plugs, my fill plug and one of the drains had a
metal gasket, and the other drain plug didn't (the plugs are identical).
The dealer parts guy says that the gasket doesn't exist.  It seems to work
OK either way.

I filled the transaxle via gravity with a several foot long tube.  As
another post mentioned, after it overflows, wait an hour and you'll get a
bunch more in.  Mine took about 10% more than the Bentley lists as the
capacity.  I used a pump to fill the rear diff.

Good luck.  It's not a horrible job, but does take a bunch of time.  After
seeing what came out, I'm really glad I did it.

Wayne Dohnal
1994 S4


>I am contemplating changing my transmission fluid and rear differential
flu=
>id in my '93 S4 to synthetic. Is there much more involved to it than
draini=
>ng and refilling? The car has 107K miles on it. Also, any reccomendations
a=
>s to what brand/type of fluids to repace them with? Thanks!
>
>Best Regards,
>
>Lance