Dennis wrote:
> Your point is why I recommend the products that go to a
40 upper weight. This will carry those warm days and extended
highway travels. During cold weather, the coolant and oil will
generally stay at slightly lower temperatures. The 5w and
10w -30 can be a problem as the weather warms and extended high
speed trips are made.

Dennis:
In the 60's we ran 20 in the winter (sometimes 10) and 30 in the summer
in my splitties, before multi-grade oils.  I don't remember if
there even was a 40 weight.  Now there are x-40s and x-50s that
are recommended and x-30 not recommended.

We drove on the new Interstates at 70+ and it was just as hot
then in Nevada and New Mexico.  We'd get 45,000 miles on the
#3 exhaust valve and 75,000 or so on the bottom end.

What's changed since those days when 30W was fine for summer?
(Besides $50,000 splitties and me getting old....)

Richard
Boulder