Why do I need a brake fluid flush?
Why is flushing important? Conventional glycol-based brake fluid is hygroscopic, which means that it absorbs water. This is important, in order to keep condensation in the brake system from causing corrosion. However, eventually,the fluid will absorb all the moisture it can hold, reaching its point of saturation. Several things can happen at this point. Unabsorbed moisture can begin to collect in the system, causing corrosion in critical areas; the water can cause seals to swell and deteriorate, further contaminating the fluid; and the boiling point of of the fluid drops beyond recommended levels. This means that under high-heat braking conditions, such as during hard braking or repeated brake application while descending a mountain, the fluid will start boiling sooner, which will reduce braking performance. The pedal can begin to feel spongy, and as braking efficiency drops, it takes longer to stop the vehicle.
Most maintenance schedules that do specify it recommend changing the fluid every two years or 30,000 miles.If you live in an unusually humid climate, it’s better to plan on doing it every year. However, your eyes can tell you when the time has come. Fresh brake fluid is transparent and has a slight amber-colored look. As the fluid absorbs moisture, it takes on a darker, cloudy appearance, which tells you it needs changing.