Stops and seals antifreeze/coolant leaks. Bar's leaks radiator stop leak concentrate 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 antifreeze 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.