The Radiator Stop Leak is designed to clog leaks in a cooling circuit containing up to 10 liters of coolant. The Radiator Leak Stop is made of vegetable fibres that can plug the holes up to 1.4 mm. If its action is not sufficient, this suggests that the holes are larger. Therefore, adding a second bottle would not solve the problem. It is then recommended to have the general condition of the circuit checked by a professional.