Bar’s Leaks Radiator Stop Leak is specially formulated to seal minor leaks up to 0.9mm in size occurring in the cooling system. Bar’s Radiator Stop Leak works on plastic, aluminum, and metal radiators. Bar’s stops leaks in heater cores, engine cooling jacket, gaskets (including head gaskets), and freeze plugs. In addition, Rhizex particles reduce cavitation by breaking-up the ultra-low pressure cavities, and reduce or eliminate the internal micro-implosions. BENEFITS: Stops internal and external leaks up to 0.9 mm in size Protects the entire cooling system Reduces damage associated with cavitation Compatible with all anti-freeze brands