Nulon Radiator Stop Leak offers a simple, cost effective solution to deal with coolant and seal leaks in radiators, heater cores, gaskets and even temporary repairs on welch plugs. Nulon Radiator Stop Leak is formulated with fibre materials designed to build up, harden and block any leaks commonly caused by simple wear and tear. It is compatible with all coolant types, including water and wonÔÇÖt harm plastics, rubber or metals including copper and aluminium. 1 bottle of Nulon Radiator Stop Leak will suit most regular size cooling systems up to about 10L.