Small Engines (Lawn Mowers, etc.): Lawn mower, stroke oil, gas tank

Question
We have a renter that we let use our gas lawn mower that is supposed to use 2-stroke oil and she used regular motor oil. There is now a gas leak somewhere on the top of the gas tank and the mower will not start. Will regualr motor oil cause this and can we flush that out somehow? We are going to hold her accountable for this and either replace the mower or have it fixed if possible.

/thanks

Answer
Regular motor oil won't hurt the mower. It won't help it either.
It definitely won't make the tank leak. That's the mowers fault not the renters.
Think about it. If you put lemonade in a pitcher and it doesn't leak, then put ice tea in the pitcher and it does leak it's not the tea's fault it's the pitcher.
Not the renters fault. How old is the mower 10 years plus? I thought so.
Just be glad you have a renter that will mow the grass.