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2004 Honda Civic Brake Fluid Question

I just took my 2004 Civic in for an oil change and they mentioned that instead of being clear my brake fluid was dark and needed to be flushed. I called my usual mechanic and he laughed at me over the phone when I told him this was the information conveyed to me. He said that he can flush the fluid, but even if he did that it would be dirty again in 2 days. My question is: What is the purpose of brake fluid? How does it work, and when it’s working properly, what color should it be? Thanks for your help!

The owner’s manual that came with your Civic will have information about how often to change the brake fluid. Is SHOULD be done periodically.

Brake fluid is hydraulic fluid. When you step on the brake pedal the brake fluid is the link to the wheels. Pressure on the pedal = pressure on the brake pads or shoes to stop the car.

It may work properly regardless of color. The problem is that brake fluid is hygroscopic, meaning it absorbs water from the atmosphere. Water in the brake hydraulic system is not good because it can cause internal rust. Who wants rust inside the brake system? Not me.

The purpose of periodic brake fluid replacement is to eliminate the water and replace all the old, dirty fluid with new, clean fluid.

I do not believe that after a brake flush the fluid will be dark again in two days. It should take much longer than that if the flush was done correctly.

I recommend having the fluid replaced at the interval specified in the owner’s manual.

I also recommend avoiding “quick-change” oil places. Why don’t you let your regular mechanic change the oil?

They must have assumed that the brake fluid was exorbitently old from the dirtiness.

Brake fluid is hydraulic fluid for brake systems. It has a certain level of “strength” so that when one “mashes the brake pedal” the fluid doesn’t compress and transfers the pressure to the brake pads. Over time, it may lose some “strength” or compressability and need to be replaced. The normal recommendation is every couple years with normal wear and tear. Age is key. The color is usually irrelevant.

Your brakes are a hydraulic system. Brake fluid is hydraulic fluid. When you push the pedal, it pushes in a piston (two actually) in a closed cylinder, which pushes the brake fluid through a tube. At the other end of the tube, the fluid then pushes the pistons inside your cylinders that force the brake pads up against the disc surfaces and stop the car.

Please recognize that this is an overly simplified description simply to explain the basic function of brake fluid. has an in-depth primer on brakes that you might enjoy reading.

To see if your brake fluid needs changing, look at the recommended schdeuled maintainence that came with your owners’ manual. It’s probably overdue. Many mechanics recommend flushing the old fluid out after 5 years of use and leaving the system filled with new fluid. The main reason is that brake fluid can absorb moisture. Many shops feel that since brake fluid is in an enclosed system and not exposed to moisture flushing with new fluid is unneccessary. All will agree that doing so is harmless.

Personally, I had mine done a few weeks ago when I had my brakes done. But, in the interest of full disclosure, for me the labor is free and the parts discounted.

Thanks so much for your help. I didn’t take it to a quick-change oil place, I just took it to a different mechanic for convenience sake because all I needed was the oil change. I’m taking it to my regular mechanic for the additional work. I just didn’t think it made sense that he said the brake fluid would be dirty again after 2 days. Thanks for clarifying.

Thanks for your responses, everyone. I’ll check the owner’s manual and see what it says, and question my mechanic about why he thinks it will be dirty again in 2 days. I appreciate your assistance!

The brake fluid will probably discolor again after going through the brake lines. That does not mean that the fluid is dirty. It’s very important to follow the owners manual schedule for all fluid changes including brake fluid.

Honda’s typically recommend changing the brake fluid every three years regardless of mileage (from the owner’s manual of my 2002 Civic, 2005 CR-v, and 2008 Ridgeline) and my older Honda (1989 Accord) says every two years.