Is most non-ethanol gas 89 octane ?

[SilverFox579]

2. Correct octane rating for your engine (87 OCTANE)

Your post say's minimum of 87 so was not sure if 89-90 would be acceptable or preferred. The station I get my non ethanol gas does a good business. Not as much as costco but pretty darn good.
I do use the cocktail religiously.

My 150 Optimax has never seen anything but top-tier 87 ethanol from a high traffic station always with Don's recommended cocktail. My tank holds 42gals and I rarely ever use that much in a season, so usually top off tank with 89 when my fishing season ends. Unlike most, I fish winter time, not summer.

Folks get wrapped up over the word 'minimum', in Mercury's application, it means "no less than" not "higher is better". Don's "choose your fuel" guidelines make that abundantly clear.