diff and gear oil s4

[sun and kath]

In the short-shifter thread I brought up the subject of oils, Swepco was recomended, but now (after searching the web) I like the look of Redline products for the gearbox and diffs.
but am not sure what to order for the Box or the diffs coz i need to know the viscosity of the standard stuff. Anyone know what oil goes in the s4 (b5)diffs and box? Is it 75w/90?
Are our front and rear diffs limited slip? or conventional? Coz if they are limited slip I may need the friction aditive.

Any knowledge welcome.

 

[jonnya]

Hi,

AFAIK, neither are LSD.
Main transmission requires ~3L of 75-90w GL-4 Fully synthetic.
Rear diff requires ~2L of 75-90w GL-5.

The consensus on AW is to stick Motul Gear 300 in both as it's GL-4/5.

 

[QuantumJohn]

All of the above is right. Once you have re-filled the gearbox oil go for a drive and then re-check the oil as it takes a little while for the oil cooler to fill. It is actually 3.4 Litres including the cooler but you might not get all the gearbox oil out unless you disconnect the pipes from cooler end as well.

You can always buy the oil direct from your Audi stealer but it is expensive and only comes in 1 litre bottles.

John

 

[sun and kath]

thanks for the help guys. that helps.
For those who are intested:
Found out from the web that the centre diff is limited slip , it is torsen - as most of you probably knew already- but helps my understanding!
It is (to be simple - as that is what i understand) cogs and not clutches. Thus on our B5 s4s we do not need to consider friction additives at all. It confused me when you said the front and rear where not Limited slip ("open" diffs) but now i understand, they achieve slip limitation by the EDL system. that is the Electronic Diff Lock, which is actually applys the breaks to the sliping wheel to send drive to the one with grip and this automatically works under 50mph. Our S4s have the 4th generation of the quattro system.

So now not only do i know what oil to safely buy - i understand the 4 wheel drive system on my S4 too!

 

[icenutter]

I've heard good things about Motul 300 as well.

 

[mas]

can anyone explain - in simple terms - the difference between gl-4 and gl-5 ?

I asked the local dealer what spec i needed and they said they didnt know - they only had the audi partnumbers £15/litre for the two types.

Local motor factor has comma semi-synth 75w90gl5 at £4.50/litre, I want to do both the rear diff and the gearbox on our 1998 tdi quattro.