Castrol brake fluid DOT 4 React Performance is a performance, high boiling point polyglycol type brake fluid designed to provide superior braking performance in a variety of vehicles, especially those that operate at higher temperatures or under increased loads. Suitable for use in all brake fluid systems in cars, motorcycles and light commercial vehicles (LCV’s) requiring either a DOT 3, DOT 4 or Super DOT 4 product. Do not use: in brake systems where a mineral oil based fluid is specified.