Yes it does. My brother cut the grass while i was on vacation. The next time i went to use it it would not stay running and it was emitting a white smoke while it was. He put a 2 cycle mix in a 4 cycle engine.
Yes it can cause white smoke in your lawnmower and it can also tear it up really fast. If it gets cold outside, then it could freeze and tear the lawnmower up completely.
Yes, it can cause white smoke in a lawnmower. It can also cause ring sticking and not enough lubrication... you need to have the proper oil mix! Eventually you can destroy your moter and end up having to pay a lot for expensive repairs or get a new lawn mower.
I believe that an improper oil mix will make white smoke in a lawnmower. Any oil mixture that is improperly combined will result in poor performance of a machine and generally some type of smoking.