I don't know about others but I usually clean off a lot of bugs and grass clippings, so some residue won't kill me. It's not like glow fuel at 5:1 that looks like you just dumped oil all over your plane.

As for the rod bearings, the lower end takes more abuse and actually makes full revolutions. The upper end is a pivet point and does not have as much movement so the bushing should not be a problem.