Brake fluid represents one of the most overlooked maintenance items in vehicles, despite its critical role in safe operation. This hydraulic fluid functions within the brake system across all operating conditions and is formulated from various glycol types, a non-petroleum based substance.
The boiling point rating of brake fluid is particularly important, along with assessments of freezing resistance, oxidation resistance, and compatibility with rubber components. All automotive brake fluid must comply with Federal Motor Vehicle Safety Standard 116, with specifications established by the Society of Automotive Engineers and Department of Transportation for both wet and dry boiling points.
Over time, brake fluid deteriorates as it absorbs moisture, which lowers its boiling point, raises its freezing point, and increases brake system corrosion. Industry experts recommend regular brake fluid changes as part of routine maintenance. While not all manufacturers include brake fluid in their scheduled maintenance guidance, those that do typically recommend fresh brake fluid approximately every 2 years or 24,000 miles up to every 3 years or 36,000 miles.
Visual inspection can reveal obvious contamination. New fluid appears clear to slightly amber,, and rusty or dirty fluid requires service. However, moisture contamination isn't visually apparent. Professional testing via strips, electronic testers, or refractometers can accurately measure moisture levels. Although drivers may not notice immediate improvements, reduced corrosion ultimately results in fewer expensive brake component replacements.
We suggest annual brake fluid testing and servicing every 2 to 3 years, ideally during routine brake service visits.