Design Engineering 040104 Radiator Relief Coolant Additive for All Water Cooled Engines, 32 oz. No mixing required; just add to cooling system and reduce engine operating temperature up to 30 degrees Fahrenheit Formulated with a corrosion inhibitor and reduces pre-existing scale build-up For use in all water cooled engines Compatible with water and all anti-freeze mixtures Safe with all alloys - 100% biodegradable, non-corrosive and non-toxic additive