Brake Fluid
A specialized hydraulic fluid designed to transfer force from the brake pedal to the brake calipers under high temperatures.
Brake fluid is a specialized hydraulic fluid used in vehicle braking systems. Its primary job is to transfer the mechanical force applied to the brake pedal into hydraulic pressure, forcing the brake calipers or wheel cylinders to clamp the brakes and slow the vehicle. It operates under extreme temperatures and pressures.
Brake fluid must maintain a stable viscosity across a wide temperature range and have an extremely high boiling point. If the fluid boils under heavy braking, it turns into a gas, which compresses easily and causes a sudden, dangerous loss of braking power (known as brake fade). The most common types are glycol-based fluids (DOT 3, DOT 4, and DOT 5.1) and silicone-based fluids (DOT 5).
Glycol-based brake fluids are hygroscopic, meaning they naturally absorb moisture from the air. Over time, moisture lowers the boiling point of the fluid and promotes internal corrosion in steel brake lines, calipers, and ABS control modules. Contaminated fluid turns from a clear golden color to a dark brown or black.
Automotive manufacturers recommend flushing and replacing brake fluid every two years or 30,000 miles to maintain stopping safety. Regular brake fluid checks ensure the system remains sealed and free of air bubbles or moisture.