AMSOIL DOMINATOR® DOT 4 100% SYNTHETIC RACING BRAKE FLUID

AMSOIL DOMINATOR DOT 4 100% Synthetic Racing Brake Fluid delivers ultra-high boiling points and low compressibility for race cars, track-day builds, and high-performance street vehicles that push brake systems to their absolute limits. It is a purpose-built DOT 4 synthetic racing brake fluid designed to maintain firm pedal feel and resist vapor lock under the most punishing conditions.

Repeated hard braking generates enormous heat in the calipers, rotors, and brake lines. That heat transfers directly into the brake fluid. When the fluid's boiling point is exceeded, vapor bubbles form in the lines and the pedal goes soft or drops to the floor. Water contamination, which is inevitable over time as moisture seeps through flexible brake lines, seals, and the reservoir cap, accelerates the problem by lowering the boiling point further. In racing and HPDE environments, where brake temperatures routinely exceed anything seen in normal driving, a standard DOT 4 fluid simply does not have enough thermal margin to stay reliable for an entire session.

ULTRA-HIGH BOILING POINTS RESIST BRAKE FADE AND VAPOR LOCK
AMSOIL DOMINATOR DOT 4 Racing Brake Fluid posts a dry equilibrium reflux boiling point (ERBP) of 580°F (304°C), well above the DOT 4 minimum of 446°F. Even after absorbing 3.7 percent water, the wet ERBP remains at 410°F (210°C), compared to the DOT 4 minimum of 311°F. That 134°F margin above the DOT 4 dry minimum and 99°F margin above the wet minimum gives real, measurable headroom during extended track sessions, endurance racing, and aggressive downhill braking. Higher boiling points mean the fluid stays in its liquid phase longer, keeping braking force consistent lap after lap.

LOW COMPRESSIBILITY FOR CONSISTENT PEDAL FEEL
When brake fluid begins to vaporize under heat, the gas bubbles compress under pedal pressure instead of transmitting force to the calipers. The result is a soft, spongy pedal that makes it nearly impossible to modulate braking precisely. DOMINATOR DOT 4 maintains low compressibility even during the most extreme racing conditions, keeping the pedal firm and predictable. For drivers running carbon-ceramic or multi-piston racing calipers on cars like a Corvette Z06, Porsche 911 GT3, or Subaru WRX STI at track events, that pedal consistency translates directly into shorter braking zones and better car control.

FIGHTS WATER CONTAMINATION
Brake fluid is hygroscopic, meaning it attracts and absorbs moisture from the atmosphere. Water enters through microscopic pores in flexible brake lines, through seals, and through the reservoir fill cap. Once water is present, the effective boiling point drops rapidly. A conventional DOT 3 fluid can lose enough boiling-point margin with just 3.7 percent water absorption to fall below DOT minimum standards. AMSOIL DOMINATOR DOT 4 counters this with a formulation that maintains a wet boiling point of 410°F, providing substantial thermal protection even in contaminated fluid. Each bottle is also packaged with a nitrogen blanket during manufacturing to purge moisture from the container before it reaches the end user, so the fluid performs at its maximum rating from the moment you open it.

STABLE VISCOSITY ACROSS A WIDE TEMPERATURE RANGE
Brake fluid must flow freely at high pressures to deliver immediate response, and it must also remain functional in extreme cold. DOMINATOR DOT 4 maintains a kinematic viscosity of 1550.0 cSt at -40°F (-40°C), well under the DOT 4 maximum of 1800 cSt, and 2.0 cSt at 212°F (100°C). This broad viscosity stability supports consistent ABS cycling, traction-control responsiveness, and pedal feel regardless of ambient or operating temperature. For drivers running HPDE events in varying climates or competing in endurance races that span from cool mornings to hot afternoons, the fluid adapts without losing performance.

SPECIFICATIONS AND COMPATIBILITY
AMSOIL DOMINATOR DOT 4 Synthetic Racing Brake Fluid meets DOT 4 specifications. It is designed for racing applications requiring a DOT 4 product. Do not mix with DOT 5 silicone-based brake fluid. It is compatible with systems that specify DOT 3 or DOT 4 fluid, but its formulation is optimized specifically for the elevated thermal demands of motorsport and high-performance driving. Consult your owner's manual for the correct DOT classification before use.

SERVICE LIFE
For maximum performance in racing applications, change the fluid once a year. Frequent track use, endurance events, and high-humidity storage environments all accelerate moisture absorption. A full system flush before each race season or major track event is standard practice for maintaining peak boiling-point protection.