>Multi viscosity oils are one of the great improvements in oils, but they
>should be chosen wisely. Always use a multi grade with the narrowest span
>of viscosity that is appropriate for the temperatures you are going to
>encounter. In the winter base your decision on the lowest temperature you
>will encounter, in the summer, the highest temperature you expect. The
>polymers can shear and burn forming deposits that can cause ring sticking
>and other problems. 10W-40 and 5W-30 require a lot of polymers (synthetics
>excluded) to achieve that range.
Exactly right. I think this thread was relative to synthetics and the
'badness' of the wide viscosity range is not nearly as bad with synthetics
as with rotten dinosaur juice.
Vorsprung durch Technik,