I have trouble restarting my mower when I stop in the middle of mowing. The dealer couldn't duplicate the problem, although they said it might be the coil. Since I'm about to give up on the mower, would it possibly help to use a different weight oil than the 30 weight recommended? Anything super easy that I could try myself? (I'm pretty limited in knowledge to work on it myself) Thanks!

No need for a heavier oil, if anything it would make the engine run hotter since a heavier oil is being harder to pump/throw around.... What I would do is check for spark, right immediatly after it cuts out.

i'm with you bug sounds like coil or plug
bob