Bar's Leak 11 Oz. Cooling System Radiator stop leak, seals internal, external, and coolant-to-oil leaks, works safely and effectively on plastic, aluminum and metal radiators, heater cores, blocks, heads, gaskets and freeze plugs, compatible with both conventional silicate-based and extended life (OAT/HOAT) antifreeze, all types and colors, can also be used in straight water, Pre-dissolved for easy installation, also lubricates water pump seal to protect against potential future problems.