Nulon Radiator Stop Leak is formulated to effectively seal leaks in radiator and heater cores, weeping cylinder head gaskets and to temporarily repair corroded welsh plugs.

Nulon R50 is formulated with a base of fibre materials. Safe for seals and hoses, has no effect on metals, including aluminium, and is safe to use in all radiators. R50 is compatible with all corrosion inhibitor and all other anti-freeze/anti-boil products.

Note: If the cooling system is dirty or restricted, first clean it with Nulon R40 Radiator Cleaner.