Hi-Gear HG9048s Insta-Seal Permanent Block Sealer - 8 fl. oz. Permanently repairs leaks in gaskets, radiators, heater cores, intake manifolds, blocks, heads and freeze plugs Compatible with all types of antifreeze and no draining required Insta-Seal fixes both large and small leaks in plastic, aluminum and cast iron intakes, heads, blocks and radiators Insta-Seal will not void the manufacturer's warranty Ceramic micro-fibers, copper and heat combine to "weld" both large and small cracks