One step formula permanently repairs larger leaks in radiators, intake manifolds & gaskets, heater cores, blocks, heads and freeze plugs. Use on cars, trucks, vans, SUVs and RVs. New 1 One Step Sealer contains an antifreeze compatible sodium silicate liquid glass formula, so no draining of the cooling system is required. It will not harm the cooling system when used properly. Use with all types of antifreeze including conventional green or blue (Silicate-based) and extended life red/orange or yellow (OAT /HOAT) coolant.