[kawasaki]

Originally Posted by jkv45

I have one old engine that didn't have synthetic oil in it during long-term storage (had fresh conventional oil), and there were rust spots on some of the steel internal parts, so I'm not buying into that theory. The engine had never been run with the conventional oil in it, yet it looked dirty upon removal. I'm speculating it's very oxidized. It's got synthetic in it now.

Clean synthetic oil is going to provide the best protection from corrosion, from everything I have learned about oil. I'll admit - I'm kind of an oil snob, and run Ester synthetics (Group V) in some of my favorite engines - just cuz.

so the best oil to use is synthetic 5w-40 as stated above?