The Wilwood EXP 600 Plus is a DOT 4 racing brake fluid sold in a 16.9 oz (500 mL) bottle, built for brake systems that run hot on road courses, oval tracks, and autocross. The manufacturer lists a 626° F dry boiling point, and it conforms to and exceeds U.S. specification FMVSS No. 116 DOT 4. That dry boiling point sits far above the 446° F minimum the manufacturer cites for DOT 4, which is the real reason to pay more than a generic street fluid.
Performance brakes generate more heat than stock hardware, and the fluid has to hold up through repeated heating and pressure cycles. The manufacturer says it protects against aeration and vapor lock by maintaining its viscosity and density to resist compressibility. Its low moisture affinity slows water vapor absorption, which matters on a street car that sees both commuting and weekend track sessions. It is also proven compatible with use in production car ABS systems, so one fluid can cover a dual-purpose build.
Fitment is application-based rather than tied to one vehicle. The manufacturer notes that DOT 3, 4 and 5.1 fluids are fully miscible, but DOT 5 silicone fluid should never be mixed with any other fluids. Wilwood also recommends a complete flush and fill with fresh fluid for all installations, and it advises that the vehicle manufacturer's fluid recommendations be followed. When bleeding, begin with the caliper farthest from the master cylinder, bleeding the outboard bleed screw first, then the inboard. Owners on user forums warn against pumping the pedal during bleeding, since that will only aerate the fluid and prevent complete bleeding. Keep fluid off pad and rotor friction surfaces, and use the bottle promptly once opened.
The manufacturer states that the fluid exceeds Department of Transportation requirements and is DOT 4 rated, so it can legally be used in a high-performance street car as well.
According to the manufacturer, DOT 3, 4, and 5.1 fluids are fully miscible, but a complete flush and fill with fresh fluid is recommended for all installations. Never mix it with DOT 5 silicone fluid.
The manufacturer advises using the fluid immediately once the bottle is opened, and not storing opened bottles or reusing old fluid.
Replacing this fluid is a routine flush-and-bleed job that most owners with basic hand tools can handle, though a clean, complete purge takes patience. The manufacturer sells a brake bleed bottle, and owners on user forums commonly favor a pressure bleeder with a rubber diaphragm, which separates the air side from the fluid side. If you replace a master cylinder, the manufacturer says it should be bled while mounted to the brake pedal assembly, and the pedal must allow full travel of the master cylinder piston for complete bleeding. Work the system from the farthest caliper to the closest and check for leaks afterward. Keep brake fluid away from pads and rotors, since the manufacturer's guidance is never to let those contact surfaces become contaminated.
