Does gearbox/transfer box and rear diff oil have to be fully stnthetic?

[Ashley g]

As above really! I'm going to be changing the gearbox and transfer box oil on My 8L S3 tomorrow and was just wondering. I've got 25l of semi synthetic 75w 90 at work so would be handy if I could. Would this be OK for the rear diff too?
Does it really have to be a fully synthetic oil?

Many thanks, Ash

 

[Broken Byzan]

It's supposed to be sealed for life, so any new oil will be better than the rubbish in it.

I have deffo used semi in cars with no problems at all

 

[Ashley g]

So semi synthetic will be ok? Can anyone confirm this? Ta

 

[beanoir]

yep, semi synth is fine.

 

[SiGainey]

seconded. Syntrax in mine with no issues