Quote:
Originally Posted by Triple Jim
Actually, one theory is that the varnish that forms with long term storage and dino oil is the protective coating that stops rust.
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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.