It is recommended by almost all car manufacturers that your vehicle's brake fluid be flushed every two years. The reason for flushing the brake system is that brake fluid is hygroscopic, meaning that brake fluid absorbs moisture (water) from the air and can cause rust to form on the internal parts of your brake system. Modern day cars have complex and expensive electronically controlled parts such as ABS, Traction Control and Electronic Park Brake assemblies that are adversely affected by water and rust.
Most newer model BMWs have a time based countdown to brake fluid service, and some models will give a state of fluid health measured in a percentage that warns you to when your brake fluid is in need of flushing. Other manufacturers tend to rely on a service center to manually test the fluid during routine service. There are other means of checking brake fluid condition using an electronic meter dipped into the fluid and a voltmeter can be used to check for presence of electrical current caused by damaging electrolysis.
Our recommendation is that if you have no record of having your brake fluid flushed in the past two years, then now is the time to have it done. Please call and make an appointment for a flush, it will save you money on expensive brake repairs in the future.