MOTUL RBF 660 Factory Line Brake Fluid is 100% Synthetic Racing Fluid - DOT 4 for extreme temperature & racing applications. All types of hydraulic brake and clutch actuators requiring non-silicone synthetic fluid. Widely exceeds the DOT 3, DOT4 and DOT 5.1 standards (except for DOT 5.1 viscosity at - 40°C). EXTREME THERMAL RESISTANCE AND STABILITY: Very high boiling point (325°C / 617°F), superior to conventional DOT 5.1 non silicone base, DOT 5 silicone base fluids, and DOT4. MOTUL RBF 660 enables effective braking even under extreme conditions. EFFICIENT WHEN RAINY: Very high wet boiling point (204°C / 400°F) far exceeds the requirements of DOT 3 & 4 & DOT 5.1 enabling brake efficiency while rainy. Reduces the risk of the “vapor lock” phenomena. Amber in color. Do not mix with silicone (DOT 5 silicone base) or mineral base fluids (LHM).