Is it slipping or "failing to engage" or shift? What symptoms was it having
that lead you to think it was time to do a fluid change now? Was the engine
operated at all before the tranny was refilled? If failing to engage then
the most likely cause is an internal leak such as a blown piston ring,
accumulator seal or something is plugging the pump inlet. Did you use
silicone or some other sealant on the gasket? Did you remove the valve body?

Drop the pan again and make sure the screen and cover plate are properly
installed and clean. The valve body can be dropped and the accumulator
checked. There is a pressure tap and a gauge can be used to do some
diagnosis. The Bentley tells how. With the valve body removed the clutch
pistons can be air tested. The synthetic fluid is not the problem. Either
the tranny was getting ready to fail or something happened when it was
opened.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Mervyn Readman
Sent: Tuesday, January 18, 2011 7:34 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Slipping Auto Tranny after fluid change

Drained the tranny. New screen etc. Put some fully synthetic fluid in and it
has some slippage problems. It goes but it is slipping during some shifts.
Anyone have any experience with this?  Synthetic fluid?  Thanks Merv