Bar's Leaks® Liquid Aluminum Radiator & Heater Core Stop Leak is the best radiator stop leak money can buy. Scientifically formulated to permanently seal coolant leaks that are the cause of most overheating problems. Liquid Aluminum is part of the next generation stop leak line which not only seal leaks, but also conditions the system. Contains Xtreme Cool™ which stops overheating and reduces water temperature. It is guaranteed to safely and easily seal leaks in plastic, aluminum and metal (copper / steel) radiators, heater cores, gaskets and freeze plugs. It will not harm the cooling system, no draining is required. Use with ALL types of traditional or extended life coolant including yellow, orange, pink, red, blue, purple and green silicate based & non-silicate based (OAT/HOAT) 50-50 mix antifreeze, and/or water. For most vehicles leaks seal instantly.