I've mentioned this before, but I almost always use 87 regular. no issue, no knock, no perceived performance degradation, mpg about 25 in normal commuting. Premium here is like 20-25 cents higher, and I'm seeing no reason to use it for how I drive. Usually at the station I go to they have 89 for the same price as 87 so I use that, but if not then the 87 is just fine. I have noticed though that with the return of colder weather my mpg has dropped about 2 to 23 rather than the almost 26 in the heat of the summer. That happens with my bike too, and that FI doesn't care for colder weather. I don't either, and carbs aren't as efficient in the cold either, but it has been a noticeable drop. I wonder if a higher octane in cold weather would be better. I may try that on the next fill just to see.