Bar's Leaks 1186 Cooling System Radiator Stop Leak seals leaks and conditions the cooling system with its advanced formula. The combination of Liquid Aluminum and Xtreme Cool offers an effective solution to heater core and coolant leaks, while also helping to prevent future issues and reduce water temperature. This product safely and easily seals leaks in plastic, aluminum, and metal radiators, heater cores, gaskets, and freeze plugs.