Stop cooling system leaks and save on costly repairs with Rislone Radiator Stop Leak. The stop leak formula is designed to minor cooling system leaks caused by normal operating wear and tear. It is suitable for use with all types of coolants and is Ideal for stopping leaks in all plastic, aluminium and metal components such as radiators, gaskets, seals and heater cores. There are 2 sizes available to cover most cooling system sizes. 177mL to suit smaller, 4 cylinder engines and 325mL for larger, 6 & 8 cylinder engines.