Correct Octane?

[Barry Loos]

I am trying to find the right fuel for my 2001 40hp-merc cycle. The manual says 87 octane or any grade above. The 87 pushes my boat at about 23-mph (speedometer). While out on the water I ran low on fuel and the only gas at the marina was 92 octane. I got some and later in the day I happen noticed that I was running almost 3 mph faster at wot. I backed off the throttle because I was afraid the higher octane would run the motor hotter than desired. I used up that fuel and now I am back to 87 octane. The motor seems ok but I lost those 3 mph. Does anyone know if using 89 octane will give better performance than 87 without running hot?

 

[Bill McElroy]

All outboards run better with the higher octane in my opinion,.....I burn 89 Octane in my Opti, but every once in a while I'll treat her to a tank of 93....i don't notice a huge difference, but almost all of my buddies burn premium in their big motors. 89 will be perfect for your motor...and you won't burn hot enough to do any damage,..infact it'll help keep your plugs cleaner and you'll have less chance of fouling.

Mac

 

[Barry Loos]

Thanks for the info. I'll go with the 89.