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Differential fluid for S5

3.7K views 13 replies 4 participants last post by  Dave Kwatro  
#1 ·
I was considering changing the differential fluids front, centre and rear and even possibly the big centre one which requires 9 litres.

Car Audi S5 4.2 semi auto 6speed

Is there any substitutes you can use and safely get away with using? I was considering using Castrol gear oil 75w90 for all 3 drive trains which I believe require 1 litre or so each... Would it be okay to use?
And would you have any suggestions for the 9 litre gearbox oil?
 
#2 ·
carefull now
the s-tronic transmission has 2 different compartments.
one contains the dual-cluthces and required ATF-oil and certainly no gearbox oil.
the other has the gears, or most of them and the differential and does require gearbox oil.
so, be carefull :cool:
 
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#4 ·
For the 6 sp auto (Tip-tronic), you need about 9 litres of Lifeguard 8 oil (green) for the gearbox.

In this box the front diff oil is separate to the centre diff/transfer box, then you have the rear diff, if non sport, then all 3 can use the same oil. On my 3.0tdi which had the same transmission, I used Castrol syntrans. But I also added Sturaco FM friction modifier to the centre diff as this quietens it at low speed full lock turns. I used to sell this as it's difficult to get hold of, but don't have it now. Or you buy the oil from Audi, which is expensive, but contains the Sturaco in it. I think you need around 1 litre except the rear diff, which may take 1.1. It's been a while since I did mine, so trying to remember.
 
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#6 ·
It is best to have it level as you will need to do the levelling off procedures for the fluid in the transmission. Put through gears, and get oil temp to between 30 and 45C, check level and put fill plug back in with engine running. Yes the diffs are a pour in up to level plug. The front diff requires you to dislocate your arm and use a fill hole the size of watch battery. The front diff was the most difficult!!
 
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#9 ·
It's just an articulated squeeze! The fill and drain is on the driver's side (UK) just where the driveshaft flange is.

Yes, I used 4 axle stands.

Tip: always take the fill plug out first! On the diffs, it is a big aluminium plug, so usually ok to take out, but you don't want to drain and then get stuck!

Are you changing the internal filter on the gearbox?
 
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#10 ·
I need to change the filter really, it's just laying on your back in a foot and a half of space is the problem with fluid dripping in your face type thing 🙃😂😂
It would be good just for a piece of mind to see how dirty it is and if there is metal shavings ect on the magnets

Might have to try and find some hydraulic jack stands so it'll make it easier to find the level and get some extra height
 
#11 ·
I did my 3.0tdi full transmission service (even though no Audi service interval for any of it! :D at 100k miles. Didn't open the filter, but oil wasn't too bad and was brown/dirty. Some swarf on the magnets, not too much.

There are 2 drain plugs on the gearbox, 1 big one that is also the level plug, so not much comes out. There is a level pipe stuck up from the sump. And a smaller normal looking plug. Undo this too so you don't get a face full of fluid! :) I lowered the sump onto the drain bowl and left it there for a little while to drip from the mechatronics inside. When you pull the filter, some more will drop, but you can work from the side so not to get any oil on yourself.

You won't get all the gearbox oil out as it has a load in the cooler, torque converter, mechatronics etc. I did start it with the sump off and this pumped a bit more out.
 
#12 · (Edited by Moderator)
I was considering changing the differential fluids front, centre and rear and even possibly the big centre one which requires 9 litres.

Car Audi S5 4.2 semi auto 6speed

Is there any substitutes you can use and safely get away with using? I was considering using Castrol gear oil 75w90 for all 3 drive trains which I believe require 1 litre or so each... Would it be okay to use?
And would you have any suggestions for the 9 litre gearbox oil?
the s-tronic transmission has 2 different compartments.