As the thread states.............
Can anyone offer any advise on what oil to use in the rear diff.

Have had a rear whining noise get worse over recent months and I am sure its not the wheel bearings.
Not sure how much just changing the oil will help, however its got to be the cheapest first thing to try?

Any help greatly appreciated

 

Assuming you're referring to an STi5 Type R, a limited slip diff oil like Castrol B373, Hypoy LS or equivalent.

 

What about Silkolene Boa 90 LS. Is this any good

 

You need a 75W-90 semi-synthetic Gear Oil for both front and rear diff in the Type R. Try Valvoline Durablend GL-5 LS for limited slip rear diffs or Castrol Syntrax which has a wide application. Alternatively Redline, Motul and Silkolene all produce similar good quality products. Recommend you avoid the fully synthetic gear oils (unlike engine oil) as they can be too thin for the Type R, and will increase potential gear grind/noise especially from cold.

 

Thanx for the replies guys.
Yes it is a STI5 Type R.

Do you think that changing the oil will make a difference to a whining diff?
Or am I putting off the inevitable.

 

I think you already know the answer to that question

 

Are you absolutely sure that the noise is not one of the rear wheel bearings? When they go it can sound like a noisy rear diff. Failing this if/when you replace the rear diff oil (0.8 litres) the lower sump plug will have heaps of metal filings attached to it if the diff has had a hard life! Give the oil a try anyway. If neither works you might need a new one.

 

So Just to confirm , I will need approx 0.8ltrs?

 

Yep it takes 0.8 litres

Dave.