For what it matters, I've been having the exact same problem w/ my '89
vanagon as several people have been reporting. Usually occurs after extended
highway driving when RPMs are down to approx. 2100 and oil light comes on.
Once RPMs exceed 2100 again, the light goes off. I had several people look at
my vanagon and mumble something about a finicky "dynamic oil system sensor,"
but was reassured everything would be OK.  This went on for months.

Now I have a new engine, and this problem has re-occurred (though not nearly
as often as before), and I am using a VW oil filter and 20W-50 oil. Since
it's much more infrequent now, I guess I'll live w/ it, but it sure would be
nice to know exactly what's going on.

Chris Parker