My Arctic Cat 1990 Jag AFS says 88 octane minimum. I have been running 89 octane. Can i switch to 87?

all gas station by me have the 10% ethanol. but that doesn't bother it at all.|||my old sled says to run premium and the only thing ran in it is regularr|||minimum 88 octane doesn't mean less than 88 octane so no you shouldn't use 87 octane, 88 or higher is what it calls for.