Budd,
the Bentley manual says to use only GL-4 gear oil of SAE 80W-90 weight
for Syncros. Other weights and specs are shown for other
transmissions/differentials but the Bentley is consistent when it comes
to Syncros. My suspicion is this is because the Syncro transmission uses
brass bushings. BTW I used Amsoil part number AGT- 1G (quite cheap) for
one gallon jugs of SAE 80W-90 100% synthetic gear oil (about one and
half gals for front diff. and back transaxle)
Larry
'86 Syncro Westfalia

<<<It is my intention to change the oil in the transmission and front
differential of my 86 Syncro.  Would synthetic oil be the preferred
choice?
 If so, are there any distinctions between Redline and Castrol?

What weight would be appropriate for ambient temperatures that range
from
-20 F in the winter to 95 F in the summer?  Would 75W/90 be best?

What is the capacity for the Syncro 094 transmission and front
differential?  (I have perused my Bentley without success.)>>>