Best oil rear diff

[S2_avant 19930325]

What oil is the best for the rear diff ?
Best regards

[oilman]

Originally it was an SAE90 meeting API GL5. That is still fine or you can modernise and use a 75w-90 also meeting API GL5 with synthetic being the top choice.

Cheers,

Guy

[S2_avant 19930325]

Great ,, do you have some opinion on for example Red Lines rear diff oil or other known brand for racing ? or 75w-90 enough ?

[oilman]

Redline is good, but very expensive once it arrives here in the UK. Not sure how expensive it is where you are, probably our most popular and suitable for race use as well is the Motul Gear 75w-90 as it is a full ester synthetic oil.

You can read up on it here https://www.opieoils.co.uk/p-899-mot...VariantID=1131

Cheers,

Guy

[S2_avant 19930325]

Great info , do you know how much oil it needs in the rear diff?
How much fits in the gearbox ?
I dont know what the former owner used for oil in the gearbox , if i need to add a bit oil in the gearbox or the rear diff ,, better to change or can add some oil that is mixable ?

[oilman]

Not exactly sure on diff capacity, but I have 1.9ltr in my head.

The gearbox takes a 75w-90 meeting API GL4, you can mix gear oils no problem but best practice is to drain and replace.

Cheers,

Guy

[S2_avant 19930325]

Hi i have pured in 0,9 liter oil in the diff and it starts running out oil threw the filling hole. 1,9 liters is impossible to fill. I had the draining plug of for a couple of days.

[oilman]

I was way out on 1.9ltr then!