Our water-based cooling system leak stop, Metallic Seal Up, is widely believed to be the top product for fixing even the most challenging leaks. It is also one of the easiest to use as well as most economical. In just a few simple steps, our product will seal radiator, freeze plug, and heater core leaks in 10 minutes, and head gasket (two bottles recommended), engine block, and cylinder head leaks in 10 driving miles.