Restore old fuel by separating the hydrocarbon chains that have bonded together since the fuel has deteriorated. An octane booster is added to replace the lost octane in the decayed fuel. Remove carbon deposits from combustion chamber components including the combustion chamber itself as well as piston(s), rings, and valves. Dual lubricants that condition the rubber and plastic components also rejuvenate rubber gaskets and seals that may have been dried out from ethanol. After the lubricants are burned in the combustion chamber, a synthetic lubricant is left lubricating the entire upper combustion chamber such as piston rings and valves. This is a fuel additive, not a replacement for 2-cycle oil. Continue to add oil as recommended by the manufacturer on the engine. Mechanic In A Bottle is registered with the EPA and is recommended by B3C Fuel Solutions for use with nonroad gasoline engines. 4 oz. bottle.