AMSOIL DOT 3 AND DOT 4 100% SYNTHETIC BRAKE FLUID

AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid delivers high boiling points, low-viscosity cold-weather flow, and broad DOT compatibility in a single bottle, making it a premium upgrade for passenger cars, light trucks, and powersports brake systems.

Brake fluid is one of the most neglected fluids in any vehicle. It operates under extreme hydraulic pressure, absorbs punishing heat from friction surfaces, and slowly absorbs moisture through flexible brake lines, seals, and the reservoir cap. That moisture lowers the fluid's boiling point over time and corrodes internal brake components. By the time you notice a spongy pedal or sluggish ABS response, the fluid has already degraded well past its effective service window.

RESISTS VAPOR LOCK WITH HIGH BOILING POINTS
When brake fluid boils, it turns to compressible vapor inside the brake lines. The result is a soft, unresponsive pedal right when you need stopping power most. AMSOIL DOT 3 and DOT 4 Synthetic Brake Fluid posts a dry equilibrium reflux boiling point (ERBP) of 271°C (520°F), well above the DOT 3 minimum of 205°C (401°F) and the DOT 4 minimum of 230°C (446°F). Even after absorbing 3.7 percent water, the wet ERBP remains at 187°C (368°F), compared to the DOT 4 minimum of 155°C (311°F). That margin matters during repeated hard stops on mountain descents, towing, or stop-and-go city driving where brake temperatures climb quickly.

FIGHTS WATER CONTAMINATION
All glycol-based brake fluids are hygroscopic. They attract and absorb moisture from the atmosphere over time. AMSOIL combats this starting at the factory: each bottle is filled under a nitrogen blanket to purge moisture before sealing. Once installed, the fluid's superior wet boiling points provide a larger safety margin as water inevitably enters the system. It also lubricates and protects the intricate pistons, seals, valves, and metal lines inside the brake system, reducing the corrosion that moisture-laden fluid accelerates.

SUPERIOR ABS AND TRACTION-CONTROL RESPONSIVENESS
Modern ABS and traction-control systems cycle hydraulic valves rapidly, requiring brake fluid that flows quickly and consistently at both temperature extremes. AMSOIL DOT 3 and DOT 4 Synthetic Brake Fluid maintains a kinematic viscosity of just 817 cSt at -40°C (-40°F), far below the DOT 3 maximum limit of 1500 cSt and the DOT 4 maximum of 1800 cSt at the same temperature. Lower viscosity at cold temperatures means faster valve response in ABS modules and more precise traction-control intervention during cold starts and winter driving. At 100°C (212°F), the fluid holds at 2.0 cSt, confirming stable viscosity across the full operating range.

BROAD APPLICATION COVERAGE
This single fluid exceeds DOT 3, DOT 4, and DOT 5.1 specifications, which simplifies inventory and eliminates guesswork. It works in the brake system of a Toyota Tundra, a Ford Mustang, a Honda Civic, a Subaru WRX, or a Harley-Davidson. If the owner's manual calls for DOT 3, DOT 4, or DOT 5.1 brake fluid, this product covers all three. Do not mix with DOT 5 silicone-based fluid, which uses an entirely different chemistry.

SPECIFICATIONS AND COMPATIBILITY
AMSOIL DOT 3 and DOT 4 Synthetic Brake Fluid exceeds the requirements of FMVSS No. 116 DOT 3, DOT 4, and DOT 5.1 specifications. It is compatible with all glycol-based brake fluids and is suitable for passenger cars, light trucks, and powersports applications including motorcycles and ATVs.

SERVICE LIFE
Change fluid every two years for maximum performance. Refer to your owner's manual for the manufacturer's recommended change interval and the correct DOT classification for your vehicle.