How Many Kilometers Should Brake Fluid Be Replaced?
2 Answers
Generally, the replacement cycle for brake fluid is every 2 years or 40,000 kilometers, but it is still necessary to refer to the cycle specified in the user manual, as not all vehicle models have the same requirements. Below are the detailed guidelines: Moisture Content: The replacement cycle is only a reference. To determine whether the brake fluid needs to be replaced, check its moisture content. Excessive moisture not only affects the stability of the brake fluid, leading to potential braking failure during continuous braking but may also cause vapor lock, reducing braking effectiveness. Method to Check Moisture Content: Prepare a brake fluid moisture tester, open the brake fluid reservoir cap, and insert the tester directly to measure. When the measurement result exceeds 3%, it is time to replace the brake fluid. If the reading exceeds 5%, it must be replaced as soon as possible, as the brake fluid may have already deteriorated.
I think brake fluid replacement depends on driving habits. I drive a five-year-old sedan and usually change it every 30,000 kilometers or every two years, whichever comes first. The reason is simple: brake fluid absorbs moisture from the air, and when too much moisture accumulates, the boiling point drops, which could lead to failure during sudden braking. Last time I changed it, I tested the fluid—new fluid is clear and transparent, while old fluid turns cloudy or even develops an odor, affecting brake response. In city traffic with frequent braking, the fluid depletes faster, so I recommend checking it more often. If you mostly drive on highways, you can stretch the interval slightly, but don’t exceed 40,000 kilometers—safety comes first. Don’t wait until the brakes feel spongy to change it, or the repair costs will be higher. At home, I check the fluid color as a simple way to judge if it needs replacement.
