Most motorists don't know that brake fluid wears out over time. They assume it is a lifetime fluid that never needs to be changed, so brake fluid is probably the most neglected fluid in vehicles today.

As brake fluid ages, the corrosion-inhibiting additives in it break down. The earliest signs of chemical decomposition can often be detected within a year or so, or after 10,000 to 12,000 miles of normal driving. Hard use that elevates brake temperatures and pressures can accelerate the rate at which the fluid additives break down even more.  Moisture also creeps into the system to further add to the contamination problem.

Fluid Checks
A simple visual inspection is not adequate because you can't tell the condition of the fluid by its color alone.  A darkish appearance doesn't necessarily mean the fluid is bad.  To determine the fluid's condition you have to test it chemically.  At Kwik Kar of Argyle we use chemical test strips that measure the ppm of copper in the brake fluid. At 200 ppm of copper the corrosion-inhibiting chemicals in the fluid have failed and it is time to replace the brake fluid.

Kwik Kar of Argyle's brake flush service:

• Contaminated brake fluid is removed from the brake reservoir
• The brake reservoir is filled with fresh brake fluid
• A flush machine is then attached and 100% the old fluid is removed and replaced with new brake fluid