Hey guys. I am new to this. I recently bought a 22" Scarab with a 260 MERC. I had no idea what type of fuel to use and filled up with 91 Octane. Do I need it for the 260 MERC motor? It is stock. Would it run better with it, or should I be running 87? Thanks in advance for your help.

87 octane works fine in the 260 mercruiser
it doesnt have the compression ratio to take advantage of 91 but it wont hurt it either

I wasn't sure. Thank you. That will save a few pennies. I know we used 91 in the 502 my buddy had.