> There are modern piston aircraft engines that not only run fine on unleaded fuel [1], but are even certified to run on standard automotive fuel ("Mogas"). No

> There are modern piston aircraft engines that not only run fine on unleaded fuel [1], but are even certified to run on standard automotive fuel ("Mogas"). Note that mogas is not necessarily the same as what one gets at a car gas station, called pump gas by some: > Automotive fuel from the pump is NOT the same everywhere you go. There are summer blends, winter blends, geographical blends within the seasonal changes, varying levels and types of oxygenates (not just ethanol) and when tanks are switched over a mixture of "in between". The pump labeling is accurate for octane, and in some parts of the world, the maximum percentage of ethanol. It doesn't tell you everything you need to know to make "pump gas" fit-for-purpose for aviation and it's not just about octane and ethanol. We need to control a wider range of fuel properties for aviation. Your equipment, your life and the lives of your passengers depend on it. Let's walk through exactly what Lycoming did in authorizing automotive gasoline - "mogas" - for our engines. It's also suggested that you read Section B of the latest revision to Lycoming Service Instruction 1070 - and read it carefully. * https://www.lycoming.com/content/unleaded-fuels-part-2 https://www.lycoming.com/content/unleaded-fuels-part-2