HEET® brand is the #1 Selling Gas-Line Antifreeze & Water Remover. It removes water from the fuel system to prevent gas-line freeze-up and harmful rust and corrosion. ISO-HEET® brand is the #1 Selling Premium Fuel-line Antifreeze, Water Remover & Injector Cleaner. It absorbs 5 times more water than regular gas-line antifreeze, while it cleans fuel injectors and carburetors. It’s designed for use year-round in ALL 2-cycle and 4-cycle gasoline engines and diesel engines.