My personal experience along with many customers is that Redline is the
oil of choice...MT-90 is what is recommended for the Vanagon...MTL is
supposed to be for the Jetta style trans but it is thinner and many have
used it for the vans.
Try it , you'll like it...someone around Portland has to carry it, but if
not, I can ship you some.
Daryl of AA Transaxle
Duvall, WA.(Seattle area)
(425) 788-4070
1-877-377-0773 toll free
http://www.aatransaxle.com (web site)

Thanks for the discussion on accessing the tranny fill port,
tools for the job, etc.

On my recently acquired '89 vanagon GL, I've got that 2nd gear
grinding when shifting issue when the van is cold.  No problems
when things warm up in five minutes or so of driving.  I'm told
that synthetic oil can reduce the severity of my cold shifting
issue and my push out my impending tranny rebuild.

Any recommendations, which brand of synth. tranny oil works well, etc.

By the way,  my other two past vanagons had a similar problem -- getting
really good at double clutching...