This is what Ben McCafferty from this list posted when I asked about MTL vs
MT90 a little while ago:

 > I'm interested in this thread, as well.  The synchro recommendations for
 > Redline -- how should I interpret this for an '85/2WD ?

I would think you could use either Redline recommendation from the syncro
site for a 2WD as well.  The MTL is a 75W80 GL-4 whereas the MT90 is a
75W90
GL-4.  The general consensus is that the MTL is better for colder climates.
Since both are GL-4 oils, they meet the needs of the vanagon tranny (GL-5
is
said to have a higher sulfur content, which eats up the brass synchronizers
more readily, though this point is debated).