Stops and seals anti-freeze/coolant leaks. Bar's Leaks radiator stop leak 2X concentrate sealer is specially designed to stop minor to moderate cooling system leaks and drips caused by normal cooling system wear and age. It works with all types and colors of anti-freeze coolant and/or water. Which is one of our commitments to customers, no matter what product you choose, our radiator stop leak or something else entirely, you can also count on effectiveness and ease-of-use. There's no special automotive expertise needed to fix a radiator leak with Bar's Leaks.