Help..Automatic Final Drive, which oil, GL4 or GL5?

[Cakewalk]

Am in the middle of renewing oil in final drive and fluid in auto 'box

I had been reliably informed EP90 GL5 for the final drive but have been told today by someone else it should be GL4 due to age of van

Which one is right?

Cheers

Ben

[Simon Baxter]

EP90, GL5 is a higher specification.
There are no syncromesh's to worry about in a final drive so it won't really make that much difference, its the manual gearboxes you have to be careful of.

[Cakewalk]

Thanx

[Red Westie]

As a side note to what Simon has said....early manual VW gearbox's use yellow metal in their syncro hubs which can react to oils containing sulphur based additives used in both GL4 and GL5. The damage apparently occurs at higher temperatures and over many miles and although both specs have this additive, GL5 has much more of it (more then twice the amount) to improve it's 'SHEER' characteristics to meet the demands of the higher spec (as for hypoid gears in differentials)
From what I can gather from my enquiries phoning several oil companies. This was more of an issue with early GL5 spec oils and later types are not as bad (remember both GL4 and 5 have these additives anyway) and that the general concensous was to either use a heavy weight old fashioned GL4 straight 80 weight or 80W90 IF YOU CAN FIND IT in a GL4 spec! (not many suppliers stock it now) OR a modern lighter weight SEMI SYNTHETIC (75W90) that shows BOTH SPECS GL4/GL5 on it's label (Carlube do one for instance) which means the oil has passed both specifications and not just GL5 (although as we all know this is the newer spec it also meets all the citeria of the old spec).
Aidan Talbot (gearbox specialst) uses the later and thats what I would recommend for our 4/5 speed manuals.

Martin