When to flush brake fluid
By Robert Blaes

The average driver applies the brakes 75,000 times per year, but most motorists don’t know that moisture in their brake fluid puts them at risk.

When moisture infiltrates the brake fluid system, it creates a number of dangerous conditions:

  • It forms acid that attacks rubber seals, preventing them from sealing correctly.
  • It creates rust and corrosion, which causes components to seize and clogs small passages and orifices.
  • It lowers the fluid’s boiling point, creating a compressible vapor, which reduces the amount of pressure applied to brake pads or shoes. This can cause poor braking or the brake pedal to go to the floor, especially in a hard braking situation.

So how do you know when to flush the brake fluid? Check for color, clarity, and moisture content:

  • Color. Light amber.
  • Clarity. No suspended particles, debris or contamination.
  • Content: Less than 3 percent moisture contamination.

Industry standards recommend a brake fluid flush every two years, sooner if you live in humid environments. This advice should match what you’ve heard from your professional technician. If not, start asking questions.

So what about those stories you’ve seen on the internet about a ‘61 Chevy that grandpa drove 250,000 miles without a brake fluid flush? Recognize that such tales fail to mention how many times he replaced the master cylinder and rebuilt the wheel cylinders. And that ‘61 Chevy? It had no ABS brake components like those in today’s vehicles, with much tighter tolerances. And 250,000 miles? The average back then was closer to 70,000, with grandpa’s mileage achievable, but a rare feat.

Many cars on Colorado roads today were built by European automakers and require regular brake fluid inspections, which about half the cars fail.

Such inspections are not required here, but someone—either the motorist, or more likely, the professional—needs to monitor the color, clarity and moisture content of their vehicles’ brake fluid.

Robert Blaes owns and operates Stang Auto Tech (www.StangAutoTech.com) with his wife Kerri. Both are Accredited Automotive Managers. Stang Auto Tech is a AAA-approved repair facility (AAR) and a ASA Gold Medallion Shop.



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