Royal Purple 11723-6PK Max-Clean Fuel System Cleaner and Stabilizer - 20 oz. (Case of 6) 3-in-1 fuel additive keeps new engines clean and improves vehicle's performance Improves fuel economy an average of 3.2 percent Increases horsepower an average of 2.6 percent Reduces hydrocarbon, NOx and CO emissions (on average 12, 13 and 18-percent respectively) Prevents rough idle, hesitation and stalling