Castrol Brake Fluid DOT4 is a high boiling point synthetic brake fluid. It is designed particularly for use in brake systems that are exposed to extreme conditions. Protects against corrosion and high temperature vapour lock. 4-LIFE is the long-lasting and time proven advanced engine coolant for road and track, used by classic car enthusiasts world-wide. Formulated using the latest additive technology to provide the highest level of protection for all classic and classic performance vehicles.