Bar's Leaks PLT11 Pelletized HD Radiator Stop Leak - 11 oz. Seal internal, external and coolant-to-oil leaks with Bar's Leaks Stop Leak Heavy-Duty Radiator Sealer. The pelletized formula works safely on plastic, aluminum and metal radiators. Designed for use on plastic, aluminum and metal radiators, heater cores, blocks, heads, gaskets and freeze plugs, Compatible with conventional green (silicate-based) and red, orange or yellow (OAT) antifreeze, Patented Rhizex pellets dissolve quickly to seal internal, external and coolant-to-oil leaks, Lubricates water pump seals and prevents formation of rust and scale, Helps to prevent corrosion and control electrolysis, 1 bottle treats systems up to 4 gallons  Protects Engine Cooling Systems Stops Current and Future Leaks In hibits Rust & Corrosion Lubricates Water Pump Seal Helps Control Electrolysis