What Octane

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Well-known member
Mar 19, 2006
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what octane do you guys that have OX66 motors use? 87 or 89, I use 87 for life of engine but now i am being told to use 89. Yamaha says 86 or better. :?:
87 ... higher octane (> 91, unless designed for it, e.g., Merc Verado 275hp) can actually not be good for aluminum head and piston motors as it combusts at a higher temperature, as the ignition point is delayed ... that's why it's "anti-knock" if you remember the Tony-the-Tiger commercials of yester-years.
I read all the time people saying up the octane you will get more power, easier cranking, cleaner burn, etc, etc. All that is a bunch of bull unless you want to waste $$$'s. Simply stick with what the manufacturer calls for and you will be alright. Who do you think knows best what fuel you should burn? The manufacturer or some know it all on the internet.
Have read several places that due to the addition of ethanol to our fuel, that the octane has dropped a couple points, and folks are migrating to 89 if the manufacturer called for 87, and going to 91 if the manufacturer called for 89.