Quote Originally Posted by Embrey View Post
90 wont hurt it, but theres no benefit to it either. actually it may lose a little power. probably not enough to notice though.90 is just more resistant to burning that 87.
I should have checked back on this thread. He's right you can go up in octane within reason but its not recommended that you go down. So if your motor says 87 you can burn mid and high grade. Some boat owners use 89 octane instead of 87 because they say the octane rating falls when the fuel sits but I don't know if thats true. The higher the octane the slower it is to detonate. That's why drag racers use 100+ octane fuel in their high compression motors. If they used regular pump fuel that would blow their motors apart.