skip to main content

Radiators are a key component in keeping engines running efficiently. Heat generated by the engine during the combustion process needs to escape or it will cause damage to the engine. The excess heat will cause the pistons to expand, and the engine will seize.

Coolant and water are pumped around the cooling system to take heat from the engine and into the radiator. In many cases, a fan then blows air onto the radiator fins which allow heat to exchange more quickly. The cooler liquid is then sent back around the cooling system to repeat the process.


Over time, valves, thermostats and water pumps within the cooling system can age and become less efficient. Alongside this, micro cracks or leaks could appear which critically hinder the running of the cooling system.

MOTUL Radiator Stop Leak has been formulated to prevent and remove corrosion within the cooling system which reduces efficiency. However, the formulation seals critical micro cracks and small leaks within the cooling system which could reduce effectiveness of engine cooling. Keeping the engine’s temperature regulated and cooling system working as it should.

/media/blog/library/additve-blogs_copy-images_radiator-stop-leak-2.jpgRecommended Use

MOTUL Radiator Stop Leak has been designed to be compatible with all types of coolant within a closed liquid cooling system.

To seal micro cracks and small leaks, pour Radiator Stop Leak into the cooling system and move the heater controls to ‘hot’. Let the vehicle idle for around 10 minutes and check the coolant level to test whether sealing was successful.

Radiator Stop Leak forms part of the additive range from MOTUL. There are a range of fuel system cleaners, injector cleaners, emission system cleaners and performance boosters for both petrol and diesel vehicles. Simply add them to the fuel tank when filling up with petrol or diesel. Repeated use of fuel system cleaners and fuel performance boosters will provide the maximum efficiency and results.

Stay in touch

Subscribe to Club Motul to be kept up to date with all of the latest product launches plus exclusive offers and sale previews.