And that lends itself to the jokes at the time about pumping ethyl.
Remember the good old gas wars before the contrived oil "crisis" in the early '70s? I remember one evening three gas stations at the same intersection in the town where I lived were trying to outdo each other. The '62 Galaxie I had at the time needed regular, which was around 95 octane. Ethyl was 100 octane.
One Saturday evening I was cruising around and these three stations had regular for 18.9 cents/gallon. I put in 50 cents worth and cruised all night.
I believe the normal price at the time was around 21 cents a gallon for regular.
along with a regular gas burner we have a plug-in hybrid. the computer will switch over to gas only mode at about the six month mark. definitely not an expert, just guessing that’s the point to consider the use an additive to keep the gas from turning to varnish, or whatever it turns into nowadays.
if you believe the station you most frequent isn’t concerned with regular maintenance, then water in their tanks is a high probability. in that case, me personally i’d then use an additive every time i filled up.