Downtown Automotive Tips: Brake Fluid Change Standards

Brake fluid is one of those maintenance items that’s easy for drivers to overlook. For one, it doesn’t have to be replaced that often and when it should, it’s often not as well-defined as an oil change for example. Brake fluid does become contaminated over time however, and needs to be replaced before damage is done.

Two of the most common contaminants in brake fluid are water and copper.

Brake fluid is hygroscopic, meaning it attracts moisture. Over several years it can actually build up a fair amount of water. Too much water in the brake fluid causes a couple of problems. First, water can react with brake system components and cause rust corrosion, which can lead to leaks. Second, the water could boil causing brake components near the calipers to get very hot. Water in the brake lines in that area can turn to steam, which doesn’t compress like brake fluid and it can really reduce stopping power.

It may seem strange to talk about testing for copper in brake fluid, but what drivers may not know is that the steel brake lines (hoses), are actually lined with copper. The copper protects the brake lines from rusting due to the water that collects in the fluid. 

As brake fluid heats and cools some of the copper lining ionizes and flows around in the fluid. This can lead to two potential problems. First, if enough copper comes off the lining, the steel in the lines is unprotected and can corrode. Second, the copper ions floating around are “looking” for some metal to bond with. This leads to copper plating in some sensitive areas like the anti-lock brake module which can hurt its function.

Generally a quick test of the fluid and a visual check will let us know if it’s time for a flush. We do brake fluid checks on our complimentary inspections. Ask your Downtown Automotive Service Advisor if it’s time for a more in-depth inspection.

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