[cliff-o2-z71]

It's been my experience that if your motor runs good on 89 octane, with out any knocks or pings, than any higher octane is a waste of money. If you stay with good gas that has the best additives, than you're ok. I think you may even hurt your performance with higher octane then you need. It's my understanding that raising the octane actually raises the flash point of gas so a higher compression engine won't set the fuel off before the plug fires. (knocks and pings)