Brake fluid is one of the most neglected fluids in vehicles today, but yet is vitally important for safe driving. It is designed to function in the hydraulic brake system under all operating conditions.

The brake fluid is made from a combination of various types of glycol, a nonpetroleum based fluid. The brake fluid boiling point is one of the most critical aspects and ratings for brake fluid. It is also rated on freezing rate, resistance to oxidation and having no ability to damage rubber parts in the brake system. All automotive brake fluid must meet Federal Motor Vehicle Safety Standard 116. The Society of Automotive Engineers and the Department of Transportation have established brake fluid specification standards for both Wet and Dry Boiling Points for automotive brake fluid.

As brake fluid ages, it absorbs moisture, which lowers its boiling point and raises its freezing point and causes increased corrosion of the brake system components. Automotive experts agree that brake fluid should be changed regularly as a part of normal routine service. Not all manufacturers mention brake fluid in their scheduled maintenance recommendations, those that do, recommend fresh brake fluid approximately every 2 years or 24,000 miles up to every 3 years or 36,000 miles.

New brake fluid is clear to a very slight amber color, if it has signs of rust or is very dirty then it definitely needs to be serviced. But moisture contamination is not so obvious, there are test strips, electronic brake fluid testers or an optical refractometer that can clearly show the amount of moisture in brake fluid. Even though a driver may not be able to notice an immediate improvement, the reduced corrosion will eventually result in less money being spent for brake system component replacement in the future.

We recommend having your brake fluid tested annually and serviced approximately every 2 to 3 years. It might be most convenient to have it serviced while a brake service is being performed.

Steve and Karen Johnston are owners of All About Automotive, providing auto repair and auto maintenance in Historic Downtown Gresham. If you have questions or comments, call them at 503-465-2926 or email them at [email protected].


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