I would stay away from the Octane boosters....also, the good kind will run like $7 to $10 so you aren't going to save much. If you don't use A/C or don't have heavy loads (like car full of people going uphill or flooring your car with A/C on), then you should be fine with using midgrade gas for a short period of time. But again, 10 cents a gallon saving times 16 gallons is only $1.60.