AP Racing Radi-CAL™ R4 brake fluid has been designed to perform better than any other product at the extremes of heavy duty braking performance in the top levels of racing. With the highest dry boiling point of any racing brake fluid currently available at 340°C, the AP Racing R4 stands alone. With outstanding resistance to vapour lock / pedal fade under the most exacting conditions. A higher vapour lock point means a firmer brake pedal at the extremes of brake temperature. Enhanced lubricity, means this fluid is an even better lubricant than PRF660 itself a market leader. This helps the life of the metal moving parts of the brake system and increases system efficiency. The AP Racing R4 can be mixed with DOT3 and DOT4 racing brake fluids but for maximum product performance the brake system should be thoroughly purged with R4 fluid.