Iso-HEET contains isopropanol and special additives including Fuel Injector Cleaner. When Iso-HEET is added to the fuel tank, this formula remains in the solution with the gasoline, and absorbs five times its weight in water. Any water in the gas tank mixes with the Iso-HEET, preventing the water from freezing in winter. Iso-HEET also removes water and condensation in warm, wet weather. Then the entire mixture of gasoline, Iso-HEET and water are burned during combustion inside the engine. Iso-HEET cleans fuel injectors and carburetors for fast starts and smooth-running engines year round.