I am having trouble finding any real data on what oil I should use in the manual transmission of my 94 hijet. My service manual book does not specify. Other resources have indicated 80W GL-3. One of the major importers told me they use 80w-90 in both transmissions and differentials and the mechanic had no idea what I was talking about when I asked about GL-3/GL-4/GL-5. Research tells me there could be damage to the synchronizers if I use GL-5 oil. But I cant seem to find anything but GL-5 oil. Any of you guys have any input to help with this subject? Thanks, Steve
