Down here in redneck country, we run avgas with some motors up to 12 to 1 and some street blower motors. we just throw in a can of marvel mystery oil per 20 gals of gal. No issues and cheaper than top oil lube. we also wipe/spray down the headers with marvel mystery oil with a mix of oil paint thinner 75% thinner and 25% marvel oil. The headers still look brand new after 2 full seasons on a sprinter, black and shiney, and they never rust.
Zip.