Ethanol fuel, a gas additive, is everywhere! Nowadays, the gas you pump from almost every gas station contains a blend of gasoline and ethanol. The percentage of ethanol blend is indicated by the E number. For example E10 means the gas mixture contains 90% gas and 10% ethanol. In automobiles, ethanol fuel won’t do much harm to your car's engine. However, when you're using gas with ethanol mixture in your outdoor power equipment, you run the risk of engine damage and incurring costly repairs.