Buslab is excellent but costly. I've found a great mechanic at Berkeley Auto
Service, 2809 San Pablo Ave., (510) 841-2568. Roger is a general VW mechanic
with none of the Vanagon fetish stuff going on, his prices are reasonable,
and  he's always done great work. In addition, he's also done a few things
for free, like setting the mixture while the van is in for a tranny repair.
Rare these days to find somebody like that. Don't know if he checks out vans
or not but give him a call. No one I know of in Oakland proper.