Hi all-I use STP octane boost In my yz400f. I also used it in my 250f. My dad buys 87 octane, and he lets me use it in my bikes, so for me it's cheaper to just use the 87+octane boost. I always use 1/2 of the bottle in 5 gallons, so it becomes 91 octane. However, it just occurred to me that running octane boost may have adverse effects. Any opinions on this would be appreciated.