It’s important to flush your brake fluid periodically. Brake fluid is hygroscopic, meaning it can absorb moisture. Evn though braking systems are essentially closed systems, they still absorb water.
Since water is heavier than brake fluid, the water falls to the lowest point of the braking system – your brake calipers and wheel cylinders. And what are those parts made of? Steel, which can rust. Brake pistons won’t slide easily over rust, so when there is rust, there is an increased risk of your brakes seizing.
If you want to avoid costly brake repairs, be sure to have your brake fluid flushed periodically.