THE BEST WAY TO TELL IS LOOKING IN THE OWNERS MANULE IT WILL GIVE YOU OPERATING REQUIREMENTS THAT NEED TO BE MET BUT I BELIEVE YOU CAN RUN LOWER OCTANE FULE WITH NO NOTICEABLE DIFFERENCE IN PERFORMANCE YOU MIGHT EXPERIANCE A LITTLE SPARK KNOCK OR WHAT THEY CALL DETONATION UNDER HARD ACCELERATION AND IF YOU DO GO TO THE NEXT GRADE OF GASOLINE