gearbox oil change
 

hello, how much gearbox oil does a change need?and how often? which gearbox oil is the best? if it makes any difference i have a 2004 wrx impreza

3.5 litres of 75/90 I used fully synthetic morris's oil, seemed about best value, bought 5 litres so I could do the rear diff as well, cost just over £30 from james Listers.

Castrol Syntrax. Best oil i have done for a while. I did have Silkolene Sylktran in mine but changed it a few weeks ago and my box feels better for it.
I have had no weird 'fly into gear' crunches like i got with the Silkolene.

Hi
Just wondering my 1996 classic import has LSD in the rear diff, if i was to change the oil in it would i need an LSD oil or would normal gearbox oil like castrol syntrax be ok?

steve