Brakes & Suspension guide
How Often Should You Flush Brake Fluid?
Written by the ASE-certified technicians at Auto Repair Shops America · 15+ years of hands-on repair experience
The short answer
Flush brake fluid every 2–3 years or 30,000–45,000 miles. Brake fluid is hygroscopic — it absorbs moisture, which lowers its boiling point and corrodes ABS components.
Why brake fluid goes bad
DOT 3 and DOT 4 glycol-based fluids absorb water from the air through hoses and seals.
Signs you need a flush
Dark fluid, spongy pedal, or a moisture test above 3%.
What a flush includes
Old fluid is pushed out of each caliper with fresh fluid of the correct spec.
Frequently Asked Questions
Can I mix DOT 3 and DOT 4?
They're compatible, but follow your manual.
How much is a brake flush?
$90–$150.
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