On Sat, 30 Mar 1996 DHaynes57@aol.com wrote:

> GL-5 is a better drade of lubricant and GL-6 is now becoming available.  The
> problem was that the GL-5 eliminates friction better than the GL-4 and VW was
> concerned I guess that thier syncro design would not work properly with the
> improved lubricant.  Instead of testing thier transaxles with the improved
> additive package or redesigning them, they just decided to keep GL-4 as the
> standard.  In fact, in the automatics, GL-5 is recomended for the final
> drives.  As for the brass parts being corroded by gear oils,  this was
> aproblem when the extreme pressure aditive packages contained sulfur.
>  Remember that gear oil smell of years ago.  Sulfur addditives are hardly
> used now and this is not a concern in an automotive gearbox.  Use the GL-5 or
> 6 and your gears will love you.  Synthetics should also be considered.  The
> extra money is cheap insurance for your expensive gearbox.
> Dennis.
> 

I do remember gear oil smelling of sulfur. But I'm still confused. If the 
"GL" classification of 6 is better than 5 which is better than 4, where 
does a GL-4 synthetic (ie Redline's MTL GL-4) fit in?

alistair