Gumout Gas Treatment removes water from fuel to improve gas quality and help extend the life of engine parts. Humidity and condensation can cause water to accumulate in the fuel system, corroding key engine parts. Gumout Gas Treatment prevents rust, corrosion, and gas line freezing. It is oxygen sensor safe and safe for use in turbocharged and supercharged vehicles. It will not void OEM,manufacturers warranty. Directions Add entire bottle to nearly empty gasoline tank, then fill tank with up to 21 gallons of gasoline. For best results, do not refill tank until near empty. Use every fill-up.