I just read a post from someone who mentioned the 'evils' of 10w40 oil 
used in their bus.  Are these perceived 'evils' only a problem in air 
cooled engines or is there something basically wrong with 10w40 altogether?

I've got an 86 Vanagon, have used 10w40 for all the time I've owned it 
and haven't had any problems whatsoever. BUT... I don't have an oil 
pressure gauge, I'll I have is one of those idiot lights, thus I haven't 
the faintist idea what the pressure reads under certain conditions.

I use 10w40 in both the Vanagon and my '78 Scirocco, which I've owned 
since it was new. Is there an advantage to using 20-50?

jk