Review on Bar's Leaks 1109 Liquid Copper Block Seal Intake and Radiator Stop Leak - 18 oz. by Ben Rodriguez

Before you use this, think about what you are doing. The instructions say to pour directly into the radiator (except for a few items for cars with expansion tanks). After using it I realized that he probably said to let the motor cool down a bit, but not completely. This gives the cooler space for more liquid. I let it cool completely. I had to put it in the overflow, although that's not exactly what the instructions say. However, I no longer have coolant losses. Several months have passed and I have driven hundreds of kilometers. I don't know if it will last forever, but it did last in the short term.