Wot oil do I use on my rear diff ???

It's a uk , x reg , awd 2000 turbo

 

75w x 90w millers is good - Fully sythetic only bud you only need like 0.8 of a littre so £12 = 1 litre

 

Or you could go with Subaru's recommendation & fill it with Castrol Syntrax 75w90

 

stupid question but how do u change the oil in the dif

 

look at the diff from the rear, loosen top plug then undo bottom one and drain, refit and fill up until oil is level with top plug.

I use Castrol Syntrax 75w-90 on mine same model/year as yours

 

use a quality fully synthetic 75w-90, and you can't go wrong, Millers, Motul, Castrol, etc will all be perfectly fine, I'm using Silkolene Syn 5 at the moment simply because it was easily available, expect to pay between £10 and £15 per litre for any of the above, also take the car for a spin before dropping the oil as getting a little heat into it will thin it and make getting all the old stuff out that much easier.

 

Silkolene Syn 5 is a very good choice, as is the Millers NT

75w-90 Gear oil