Stops Overheating Reduces Water Temperature Pro-Blend guarantees instant results from this radiator additive. Add 30 Oz. per 2 gallons or- 60 Oz. per 4 gallons of water (or coolant). Product does not need to be applied every time the system is flushed, but 60 ounces are needed to reduce temperatures 40?. Perfect for racing, towing and daily drivers with air conditioning.