Radiator Bar's leak cap is specially designed to seal small leaks and drips in the cooling system and reduce or eliminate cavitation Bar's Radiator Leak Tapes works on plastic radiators, leaking aluminum and metal, heating cores, blocks, cylinder head gaskets, freeze seals and plugs Shake well and the all contents into the radiator (not into the overflow tank) after the engine cools and replace the radiator plug and drive or run the engine for at least 15 minutes Seals leaks throughout the cooling system and helps keep the cooling system clean, reduces or eliminates cavitation damage