C&R Stop Leak is an item that can prevent a DNF in the event of a radiator puncture, cracked cylinder head, or head gasket problem. Many race cars have dropped out of races because of these problems. Up to now, the drawback of using stop leak was the residue that it left behind. Most stop leaks use ceramic and rely on air to make it coagulate and plug a hole or crack. This works well but the bad side effect is that when the water is drained from the system during an engine change, the stop leak will dry inside of the radiator, heads, and engine block leaving a ceramic coating. Ceramic is a good insulator but this is not what you want inside of your cooling system. Even products that don't contain ceramics will leave a residue. Any residue or coating inside the tubes of a radiator will reduce its efficiency. After extensive research, C & R Racing has found a stop leak that doesn't leave a residue. C&R Stop Leak stays suspended in the water so that when the water is drained, all of the stop leak is drained with the water leaving no residue.Pit Stop USA offers C&R Racing Cooling System Stop Leak 1000000001 at low everyday prices. Be sure to check out all of our products from C&R Racing Radiators including C&R Racing Radiators Coolant Additive and C&R Racing Coolant Additives.