Mechanic In A Bottle 4 oz. Small Engine Additive. A clear liquid that cleans engines with issues related to varnished carburetors, water in the tank, carbon deposits, ethanol, and old/poor quality gas. It effectively removes all varnish in the fuel system without the need to remove the carburetor from the machine. This additive contains rubber and plastic conditioners, revitalizes old fuel, safely dissolves varnish/shellac, and acts as an anti-corrosive/metal deactivator. It also serves as a carbon cleaner, octane improvement, fuel stabilizer, high-temperature detergent, and upper cylinder lubricity enhancer. Please note that it is not a replacement for 2-cycle oil.