Yep.  I blew out a filter on startup at about 17 degrees with 20w-50 on my
'84 with a fresh rebuild in it (heavy duty pump too). This was shortly after
I blew up a used 2.1. What a mess, I think it pumped out the whole crankcase
in the five seconds before I noticed the oil light and gauge at zero. It
rarely gets that cold around here, but I now run Mobil 1 15w-50.

If you want to really know what's going on with your engine and bearings,
install an oil pressure guage.  Ignorance is not bliss with waterboxers,
especially with the 2.1s!  VW knew this, and that's why they installed two
pressure sensing systems.  In my experience, when those rod bearings go they
go fast and without warning other than with low oil pressure or a very hard
knock you can easily tell from tappet noise (In my case in about 3000
miles). If you hear that knock, stop driving if you want to have a core to
rebuild!  I didn't and it cost me.

Stuart

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Dennis Haynes

Even in a worn out Waterboxer, 20w-50 should not be used in cold weather.
Synthetics give a bit more leeway but as you near the teens many destructive
things can happen with too heavy an oil.  For the winter I even go down to
the 0w-40 European formulae for my daily drivers. If I have to drive Fun Bus
to work on a cold day with the Mobil 1 15w-50 I let it warm up a bit and
drive extremely gently until I see the oil pressure drop a bit on the gauge.

Dennis