> of any oil other than a straight GL-4 voids the warranty on the 
> synchronizers!  GL-4 oil is available from Pennzoil, Valvoline, and 
> many other manufacturers.  Do not be talked out of GL-4 by your local 
> supplier who may not have it!  VW & Audi synchros were desinged for 
> GL-4 oil; anything but GL-4 oil will cause hard shifting and possible 
> damage to unit.  Really!  Trust us on this one.

> ***end of quote***

This has been thoroughly discussed on the corrado list and apparantly
is true, the oil must be GL4 and GL4 only, apaarently the GL rating
indicates the type of wear additive formulation and does not work
on a GL5 is better than GL4 sort of system, this comes from people
who race VW's, from the owner of ND Turbosystems and others in the
high performance VW know.  Some say Redline MTL, GL4 but an 80W90 I
believe is OK, parrticularly for vans but others claim horror stories.
A full analysis is presented in the h20 vw FAQ's at MIT.  The oil of
choice is Redline MT90 but it is cautioned the Redline seems to be
out of business now days, most suppliers still have stock though.

John
ja@coe.wvu.edu
'71 Westy Virginia, '90 Corrado G60