Bar's Leaks liquid aluminum is part of our next-generation stop leak lineup that not only seals leaks, but also conditions the system. With this formula, you're getting a solution to your immediate problem plus a preventive tool for avoiding future issues with heater core leaks and coolant leaks. This product also contains Xtreme Cool, which stops overheating and significantly decreases water temperature. The combination of these two elements are guaranteed to safely and easily seal leaks in plastic, aluminum and metal radiators, heater cores, gaskets and freeze plugs.