Quote:
Originally Posted by JRMichler
Good clean oil is important on the cam lobes. The high loads and small contact area result in a thin oil film. Dirt in the oil acts like grinding compound and wipes out the cam lobes.
(SNIP)
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That may be even more true now that regular auto oils have lower levels of Zinc and Phosphorus (ZDDP) to help the catalyst have a longer lifespan. The lower levels can present galling problems for cams with non-roller lifters - especially at cold start-up.
"Racing" oils generally have higher levels, as do most cycle-specific oils.
Most, but not all, diesel oils still have higher levels. One interesting note about Shell Rotella - conventional and synthetic multigrade oils both have high levels, but the straight-grades don't. Go figure...