A Change for the Better? Just Ask Your Brakes

When and why you should change your brake fluid

Changing the many fluids in a vehicle is always a change for the

better. Dirty engine oil, transmission fluid or anti-freeze are bad

news for a car. But what about brake fluid? Many motorists know that

this fluid should be topped off, but changed?

According to the Car Care Council brake fluid in the typical

vehicle can become contaminated in two years or less. This is

because the fluid absorbs moisture, which works its way through the

hydraulic system. Under heavy braking conditions, such as those

encountered in mountainous or hilly driving or when towing a

trailer, moisture in the overheated fluid vaporizes (boiling point

of water is lower than that of brake fluid) and braking efficiency

is reduced.

"Even under normal driving conditions this condition can develop

if the brake fluid is seriously contaminated" says Rich White,

spokesperson for the Car Care Council. "Not only is the fluid

vulnerable to vaporizing, it also can freeze.

Brake fluid must maintain a stable viscosity throughout its

operating temperature range. If it's too thick or too thin, braking

action is impaired. Beyond the vaporization hazard, moisture creates

an additional problem for owners of vehicles equipped with anti-lock

braking (ABS) systems. Rusted and corroded ABS components are very

expensive to replace.

How does a car owner know when to have fluid changed? The Council

recommends replacement every two years or 24,000 miles.

"Certainly it should be included with brake pad or shoe

replacement," White emphasizes. "In between, as a preventive

measure, a professional brake technician should check the condition

of the fluid with an accurate fluid test safety meter, which is

inserted into the master cylinder reservoir to record the fluid's

boiling point

Before it's here, it's on the Bloomberg Terminal.