Will immediately seal small leaks caused by external damage, porous solder joints and hairline cracks in cooling systems of all water cooled engines. Coolant is prevented from entering the combustion chamber due to internal leaks from head gasket etc. It does not react with oxygen or heat and will never prevent system flow or cause overheating. Radiator Stop Leak works as long as its in the coolant.

radiator leak sealant

Liqui Moly Radiator Leak Sealant