 You can learn more at peakauto.com. K-Seal fights the most difficult coolant leaks, including head gaskets and engine blocks. And now there's K-Seal Ultimate, featuring 33% more sealing power than the original K-Seal. K-Seal's unique formula works with all water-cooled engine castings, including aluminum. No need to drain or flush your cooling system. Just shake the bottle and pour K-Seal Ultimate into the cooling system, and you're back on the road.