What is the octane booster in ethanol free?
Octane likely. That’s part of why it’s $12/gal.
The stuff also smelled good. It likely had no shortage of Benzene either. Smelled like the gas of my youth.
Fortunately I located a gas station ~20 mi from home
(and was on an occasionally traveled path for other reasons) that has an “RV” pump of ethanol free gas. It sells for ~$1/gal above the ethanol laced gas.
There was no way I was going to put ethanol in a new lawn mower.