what is the best rear diff oil for a 99 impreza turbo and how do i refil it ?

 

Try Oilman in the traders section for your oil

On your rear diff casing there are 2 plugs (upper and lower).. drain the old oil out by removing the lower plug (a half inch square socket will undo it). Once oil has drained refit plug and undo the upper plug.. Filling is a pain in the *** (you will need 0.80 litres of oil)
Best to use a syringe (spelling) or a pump as its almost impossible to get the oil into the diff otherwise!!
Once filled then retighten the plug, job done.

Job is a bit easier on a ramp or jacking up the back end but only after you've drained out the old oil....

There is also the option of removing the diff completely to do the refill...

 

I use Motuls Gear 300 and don't forget the sealant when replacing the drain plug.

 

Make sure that you put the right amount of oil in rather than fill to the level plug.

It's a common fault that people with plated LSD's fill to the level plug - not allowing for the fact that the LSD is taking up all the space where the oil should be. Thus underfilling by quite a bit and getting noisy tm's as a consequence.

Good Luck David APi Engines / APi Impreza
www.apiengines.com

PS 75W /90 is what the book says. That's all that is necessary. Synthetic if you wish.

 

do you use gearbox oil or is it diffirent stuff. i remember my box oil was 75/90 semi.

 

75W/90 is 75W/90 - gear oil of course suitable for gearbox or diff.

David APi