I've had zero issues with 10% ethanol in lawnmowers, snowblowers, chainsaws, leaf blowers, or the Holley 750 that I installed on my Duster in 1999. The gas sits in the lawnmower and Holley 750 year round. I do run the snowblower, chainsaw and leaf blower dry at the end of the season. The octane rating only indicates the level of resistance of the fuel to burn, and shouldn't affect anything else.