Red Line Lead Substitute Red Line Lead Substitute is designed for vintage engines originally built for leaded fuel, helping to protect valve seats from the harshness of today's fuels. It also cleans deposits in carburetors and injectors, making it a comprehensive solution for maintaining older engines. Plus, it's safe for use with catalytic converters, ensuring a smoother drive without compromising the vehicle's emission system. Features: Prevents valve seat damage in engines designed for leaded gasoline Prolongs the useful life of older engines without updated valve seats Safe for catalytic converters Cleans carburetor deposits and injectors For racing, marine or off-road use only One 12oz bottle treats up to 25 gallons