Johnson/Evinrude Carbon Guard Fuel Additive 12ozJohnson/Evinrude Carbon Guard is a gasoline additive formulated to minimize deposit build-up in 2-cycle and 4-cycle marine engines when used as directed.Benefits: Reduced possibility of piston ring sticking; Reduced carbon build up on 4-cycle valves; Better overall engine performance; Increased engine life; For 2-Cycle and DI engines: Add 1 oz. of Carbon Guard for every 8 gallons of gasoline.For 4-Cycle engines: Add 1 oz. of Carbon Guard for every 16 gallons of gasoline.