Good radiator stop leak products include Bar's Liquid Aluminum Cooling System and Stop Leak, Dike's Temporary Radiator Stop Leak, and K-Seal's Multi-Purpose One Step Permanent Coolant Leak and Repair. Bar's received a five-star review on Autozone's website, and both Dikes and K-Seal's products garnered positive reviews on Amazon.com.
Bar's Liquid Aluminum Cooling System and Stop Leak is formulated to apply a permanent seal to radiator leaks and condition the entire cooling system. It boasts patented Extreme Cool technology that immediately stops the radiator from overheating and reduces the coolant temperatures. It efficiently seals leaks in multiple mediums, including plastic, aluminum, copper and steel. Bar's Liquid Aluminum Cooling System and Stop Leak is not only used for radiators; it is also compatible with heater cores, gaskets and freeze plugs in any vehicle that uses green, blue, red, orange or yellow antifreeze.
Dike's Temporary Radiator Stop Leak is meant to seal small leaks in radiators. It can also be used as a preventative treatment to stop leaks before they start. To use the product, pour a can into the radiator and run the engine for 15 minutes. Cooling systems that hold more than 4 gallons require 4 additional ounces of Dike's per additional gallon.
K-Seal's Multi-Purpose One Step Permanent Coolant Leak and Repair is for use on the radiator, cylinder heads, engine block, head gasket and heater core. It is also appropriate for repairs on the water pump casing and freeze plugs. To use, shake the container, pour the contents into the radiator, and run the engine.