Common Aviation Fuels, Mogas
The Federal Aviation Administration regularly publishes Advisory Circulars about aviation safety issues, these are mandatory reading material for pilots and aircraft owners.
FAA Advisory Circular 91-33A
The use of alternate grades of aviation gasoline for grade 80/87, and use of automotive gasoline in aircraft.
Excerpt from the document:
This circular provides information relating to the use of alternate grades of gasoline when Grade 80/87 aviation gasoline is not available and to the resultant effects of the use of alternate fuels which have higher TEL (tetraethyl lead) content. Suggestions are offered as acceptable means of avoiding engine operating difficulties when using alternate fuels. This Circular also provides suggestions for added safety in the use of automotive gasoline in those aircraft engines and aircraft covered by Supplemental Type Certificates (STCs).
Aviation gasoline demand has decreased steadily to a relatively insignificant portion of the total oil market. Escalating production costs and other factors have caused the oil industry to improve its economics by providing a single grade of aviation gasoline, Grade 100 low lead (100LL), which would be suitable for most current and projected piston aircraft engines.
To continue reading see the pdf below: