B7 RS4 Gearbox and Diff Oil

[Tas_Audi]

I know there have been a few discussions around engine oil for the RS4 but what is being used for rear diff and gearbox oils. I am going to replace both but have not decided on what brand to use. I am leaning towards Motul Gear 300LS 75W90 for the rear diff and Motul Gear 300 75W90, both are API GL5.

Anybody used Mobil, Fuchs or Valvoline gear oils? As long as they are GL5 specifications I am open to suggestions.

I have a month before I'm home again so opinions welcome.

[zoojezza]

Tas that is one hell of a specced up car you have...must be awesome....jezza

[Alister]

I did the gearbox and rear diff in my old RS4 with RedLine MT90 oils. Don't have the exact specs immediately on hand but can check what I used if you like. FWIW it was a different spec for the gearbox vs diff.

[Milka]

From what I know gearbox should be GL4 and diff GL5. GL4 is not worse than GL5 but rather specific for a different purpose, mainly synchro gearboxes as pure GL5 can kill synchro gears, there are some like Motul that are both 4 and 5 spec


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[ParkertR]

I've used Fuchs and added repco's manual transmission additive. Did wonders to my shifting!

All tools required are in the small toolbox at the back of your car, including the torx bit to unscrew the filler cap.


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[Tas_Audi]

I did the gearbox and rear diff in my old RS4 with RedLine MT90 oils. Don't have the exact specs immediately on hand but can check what I used if you like. FWIW it was a different spec for the gearbox vs diff.

Alister, Oil specs would be great. Diff would have been GL5 and Gearbox GL4

[Tas_Audi]

From what I know gearbox should be GL4 and diff GL5. GL4 is not worse than GL5 but rather specific for a different purpose, mainly synchro gearboxes as pure GL5 can kill synchro gears, there are some like Motul that are both 4 and 5 spec


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You are correct the Motul 300LS 75W90 is GL5, diff, and the 300 75W90 is GL4/GL5, gearbox.

[Alister]

Alister, Oil specs would be great. Diff would have been GL5 and Gearbox GL4

OK, I used the following:
* Red Line MT90 gearbox oil (required 3.2 litres)
* Red Line 75W90 diff oil (required 1.1 litres)

You are correct on GL5 for the diff and GL4 for the gearbox.

[Tas_Audi]

OK, I used the following:
* Red Line MT90 gearbox oil (required 3.2 litres)
* Red Line 75W90 diff oil (required 1.1 litres)

You are correct on GL5 for the diff and GL4 for the gearbox.

Thanks, I'll have a look at Red Line oils

[Nathan|RS4|]

At the last service I asked for a quote to change the gearbox and diff oil. It'd only done about 27k but thought it wouldn't be that much so why not. They came back with a ridiculous quote and the Audi dealer mechanic explained how the gearbox was "sealed" and didn't have a drain plug. The oil didn't need changing for life. My comment back was that it would be a short life. The mechanic went on the say that if they were to change it they'd need to suck it out the filler tube. Raised my eyebrows but haven't looked for a drain plug on the gearbox.

Does it have one?