I use straight 30 (winter) and straight 40 (summer) Castrol HD in my '61 bus.  FWIW I use 15W40 (winter) and 20W50 (summer) Castrol Durablend in my Vanagon.  I use 15W50 Mobil 1 in my GTI year-round.  

On a similar related note I just put 3300 miles on my Vanagon last week with a fresh oil change, I use a Mann filter (as usual) and Castrol Durablend 20W50.  It used 1 quart, mostly from a leaky oil pump cover plate and drain plug.  I had to put a timesert in the drain plug hole after it stripped a while ago, it seeps a little now...  Anyway the oil is still gold, I'll wait to change it until it gets black.  

I'm still working on the photos from the trip (RMMW show and Yellowstone), I'll post when they are available.

Dave
251.org
'87 Vanagon GL Wolfsburg (186k)
'61 Microbus (80k)
'88 GTI 2.0 16v (162k)

>I am ignorant of why straight weight even exists anymore. (and on a lot
>of
>other topics as well)