Unleaded Fuels

Automotive Fuels for Aviation

For decades, general aviation has been operating and designed around a single fuel - 100LL. Now environmental and economic pressures are driving the search for an unleaded alternative. Lycoming firmly believes that an equivalent performance unleaded aviation grade replacement for 100LL is the best total solution for our industry overall. We also know that using automotive blends in aviation is possible for certain engine models if you put the correct controls in place on the fuel. Lycoming's consistent objective is to give our customers as many fuel choices as possible while still maintaining airworthiness.

In the following three articles, Lycoming specifically addresses the topic of automotive fuels for aviation, including our approval to operate certain Lycoming O- and IO-360 engines using an automotive specification fuel. Lycoming strongly recommends a thorough review of the latest revision to Lycoming Service Instruction 1070, "Specified Fuels," which is available online at www.lycoming.com/support/publications/service-instructions/pdfs/SI1070Q.pdf

Two terms are used repeatedly throughout this series: "pump gas" and "mogas." "Pump gas" refers specifically to fuel that conforms to the ASTM D4814 or Euronorm 228 specifications for automotive fuel and is available for retail purchase at automobile filling stations. "Mogas" refers specifically to fuel that also conforms to the ASTM D4814 or Euronorm 228 specifications, but controlled and labeled differently such that it is "fit-for-purpose" for aviation.

Part 1: Airworthiness by Design

Part 2: Pump Gas is not Mogas

Part 3: Avgas by any other name... is Avgas

Additional Support Resources

Key Reprints

Unleaded Fuels

Engine Troubleshooting Guide

Maintenance Publications