Hi all,
I've been driving around a lot in CO with temps in the upper 90s, and have
noticed an increase in the incidence of the oil pressure light/buzzer when
the engine is at its hottest.  I am currently running Castro 20W50
non-synthetic and Mann oil filter.  (I have had the usual intermittent
Vanagon buzzer when decelerating from highway cruises).  I can only assume
the oil is hotter and thinner, and being compressed out more easily?

Looking in the owner's manual at oil recommendations, I see that 20W50
really doesn't go up to these temps, and I think the fact that the engine
works harder at altitude and on hills doesn't help things.

I see that SAE40 is recommended from about 80F to 100F, and am planning to
make the switch for the remainder of the hot summer weather.  Anyone out
there in severe heat given this a try?  Results?  Favorite brands?

Thanks, and I'll post my results to the list when I have them.
bmc  :)
"Faith will move mountains, but you'd better bring a shovel...."