Only used octane booster once and that was after I ran out of gas and had to purchase regular gas in place of the premium that I needed (station was all out of premium and was the only station in town). Car pinged like crazy and had no power. Used a bottle of 104+ until I could bet to a station with 93/94. A lot of money for a little bit of nothing. About $6 for less than 8 ounces. That works out to be about $96/gallon.