Basic fuel question.

[Will5150]

This is my FIRST 4 stroke 2008 Yamaha F90. Should I be using 91 octane ?
thanks.

[BOATS]

Been running non ethanol 89oct in my 2012 F115 with no issues.

[Will5150]

Thanks Boats,
Will5150 (BM2 76-80) ��

[RyanJ]

Run whatever....just put some startron in each tank it'll be fine.

[BOATS]

Thanks Boats,
Will5150 (BM2 76-80) ��

Anytime

[Tx Champ]

I've read on here that the 3.3L 2 strokes are prone to detonation. I don't know if that's true for the four strokes. For that reason, I always run the highest octane I can get (90 or better) and always run a Top Tier brand. Unfortunately non-ethanol gas is a thing of the distant past around here.

[BBW]

i have always run non-ethanol but just purchased a new boat with 175sho manual called for 89 all the non- ethanol i find around here is 87 what do think about running 87 non-ethanel

[ajw18]

We have 89+ octane non-ethanol around here so that's all that I've run in my 175 SHO.

If my options were 89+ ethanol fuel or 87 non-ethanol, i'd run the proper octane fuel regardless of ethanol and use fuel stabilizer. The new outboards are supposed to be designed to run ethanol. I don't know what I'd do if I still had my old carb 2 stroke.