On average, if you drive between 10-15K per year, you will hit his brakes over 75,000 times a year. Because adequate braking is vital to safe driving, it is important to check your brake fluid levels regularly.
Regularly changing your brake fluid will prevent expensive brake components from early failure. Ideally, you should change your brake fluid every two years but this will vary depending on your vehicle.
Brake fluid transfers the energy from your brake pedal to the brake callipers, which squeezes the brake pads together against the brake rotor. This creates friction and heat which stops the vehicle. During this process, your brake fluid is subjected to very high temperatures over 300 degree. For this reason, brake fluid must endure very high temperatures and not turn boil off and vaporize.
Over time, brake fluid will be come dirty and contaminated. This dirt can damage your brake rotors and cause them to decrease performance. Dark brake fluid indicates a high water content.