E10 destroyed my John Deere lawnmower, according to the small engine mechanic I took it to. Of course, the electric start Toro walk-behind I was eyeing might have had something to do with his opinion.
I just buy pure gasoline for my riding mower, small gasoline engines, motorcycles, and pre-millenial cars. All of them run better and get better mileage on pure gas. You can actually feel the difference. For my newer cars, it doesn't matter as much. They run fine on E10.
I have two stations selling ethanol-less gas within 5 miles of my house. It's worth the effort. You can look up stations at the following website:
http://pure-gas.org/index.jsp