Brake Fluid Boiling Point Chart

One of the key aspects of brake fluid quality is the temperature at which it boils. A comparison of the boiling points for DOT 3 (in general), Ford DOT 3 and DOT 5 brake fluids is shown. If brake fluid boils in the brake system, it forms vapor which reduces the ability of the brake system to develop hydraulic line pressure. If brake fluid boils, the system acts just like a system with air in the lines, except that it reverts to normal operation when the brakes cool and the vapor condenses.

BRAKE FLUID BOILING POINTS MINIMUM FEDERAL SAFETY STANDARDS

Dry Wet Dry Wet

DOT 3 401° 284° 205° 140°

DOT 5 500° 356° 260° 180°

Ford 550° 550° 288° 288°
DOT 3 Exceeds Exceeds Exceeds Exceeds
Require- Require- Require- Require-
ments ments ments ments

NOTE: A newly opened can exceeds all minimum requirements.

Brake fluid absorbs moisture out of the air and must be stored in the original container with the cap securely fastened. If not, its moisture content will increase and the boiling point will drop. Moisture also will be absorbed while the fluid is in the brake system, but a properly capped and sealed brake master cylinder reservoir (2K478) will limit the rate at which this occurs.

NOTE: For more brake fluid information see Fundamentals and basics.