As already mention, run the recommended octane, which is 87.
Anything else is a total waste of money and won't improve performance or increase mileage at all.
Higher octane gas simply burns slower and is harder to ignite.
If you're having pre-ignition (knocking) with 87 octane under normal conditions, then, simply, you've got something wrong. Timing advanced too far, carbon buildup in the cylinders/piston tops, wrong temperature range spark plugs, etc.

Fred
Anything else is a total waste of money and won't improve performance or increase mileage at all.
Higher octane gas simply burns slower and is harder to ignite.
If you're having pre-ignition (knocking) with 87 octane under normal conditions, then, simply, you've got something wrong. Timing advanced too far, carbon buildup in the cylinders/piston tops, wrong temperature range spark plugs, etc.
Fred