Both Lycoming and Superior aircraft engines can be adjusted to function on high octane automotive gasoline.
Due to the prevalence of Ethanol in gasoline in the United States, it is almost impossible to ensure a pure supply of Ethanol-free gasoline. Regardless of what the pump advertises, the fuel delivery person can’t be depended on to make sure no Ethanol enters the fuel system of your aircraft. Ethanol is damaging to the seals and other components of an aircraft engine. Contamination from the debris of deteriorating hoses and seals can be disastrous in an internal combustion engine.
If you are in a part of the world where Ethanol is not used in gasoline, you may have some assurance that automotive gasoline is not contaminated. If you are in the United States, all fuel should be tested to assure that Ethanol is not present.
