The unique anti-rust formula has been specially developed to permanently repair and seal most leaks in head gaskets, radiators, cylinder heads, freeze plugs, heater cores and engine blocks. Once added to the radiator tank, Nitrox Steel Weld will get to work stopping leaks fast, whilst also staying active to seal any further leaks. The powerful formulation mixes with ALL types of anti-freeze already in the cooling system, so no need to flush out.