Brake fluid color can be a confusing topic. It's one of those things that seems to differ depending on who you talk to (and what they are selling!). Luckily it's not as complicated as some people make it sound. The next time you are changing your brake pads or just doing a general check of your fluids, be sure to pay attention to your brake fluid. Let's take a look at what it looks like when it is bad.
When you buy a new bottle of brake fluid, it looks almost clear with a
bit of yellow tint to it. Whether it is DOT 3, 4 or 5, all brake fluid is pretty much the same
color. While you can't expect that it will remain this color for five years,
it should still be somewhat clear when you look into the brake
The image below is a great example of what your brake fluid should NOT look like.
Most likely this fluid has not been changed for at least five years or more. You can see that it is very dark and almost looks like used motor oil. As the fluid is used it gets darker and darker, much like motor oil. Anything from dark brown to black is a bad brake fluid color.
If your brake fluid appears dark brown to black in color, then you need to have it flushed out and new brake fluid put in. When brake fluid color change, it means that it has been collecting grime and debris from the braking system and it might even have absorbed some water.
Under normal braking conditions this isn't too big of a deal, but if you are doing some extreme braking then you might find that your brakes aren't working like they used to and you may even suffer from brake fade. Obviously we want to avoid this problem so a brake fluid flush is in order.
Dark brake fluid will not cause any long term or extensive damage in general... but over a long period of time, it could cause the rubber seals in the master cylinder and calipers to deteriorate. When that happens, brake fluid will leak out and the braking system will begin to fail.
While doing your routine maintenance, be sure to check the color of your brake fluid to see if it needs replacement.