Is Dark Brake Fluid Bad? (Black Color)

When you buy brake fluid, it usually looks transparent or clear. However, this does not go on for good. With time, it becomes dark. In this article, we will find out is dark brake fluid bad?

We need to know the right color for brake fluid. We will also look at whether you can drive with black brake fluid or not. In the end, we will also analyze the aspect of mixing old and new brake fluid. How safe is this practice?

is dark brake fluid bad

Is dark brake fluid bad?

Yes, dark brake fluid is not good. It does not matter whether you refer to dot 3, dot 4, dot 5, or dot 5.1. As long as that brake fluid is dark, it is bad. This is because brake fluid only becomes dark after extended use. It will darken if you have not changed it in a long time.

When brake fluid is dark green, there are contaminants that are responsible for that color. Some of them come from tiny pieces of brake lines which wear away. Brake fluid is corrosive by nature. Designers are well aware of this. That is why they select corrosion-resistant materials. But, if the brake fluid is not changed for too long, it gradually corrodes the brake lines.

What color is good brake fluid?

Good brake fluid should be transparent or clear. But it comes in many other light color. Brake fluid color depends on the type of brake fluid. But almost all of them are yellow or amber. Below are some commonly used colors for different brake fluids:

  • Dot 3 brake fluid: Its colors include amber or light yellow, shades of blue, and transparent
  • Dot 4 brake fluid: It can be gold or amber 
  • Dot 5 brake fluid: It is usually purple  
  • Dot 5.1 brake fluid: This one comes in shades of red, transparent, and blue

What makes brake fluid dark?

Many factors make brake fluid dark. The first one is the age of brake fluid. If you have been using that brake fluid for too long, it starts deteriorating. This means that when it becomes black, you have to change it. Other factors that contribute are as follows:

Moisture in the fluid:

Brake fluid can absorb moisture in small proportions. When the moisture condenses, it becomes water. With temperatures rising, the moisture evaporates. This invites air and other tiny foreign particles into the fluid.

Heat in the system:

Brakes convert kinetic energy into heat. They do this by allowing the brake pads or shoes to rub against the rotating member. In the end, the motion stops. This heat affects the brake lines and enhances the breaking away of minute particles of brake lines. These end up in the brake fluid.

Passive corrosion:

With time, the corrosive nature of brake fluid takes effect. Even when the best materials are selected, the fluid gradually corrodes the brake lines. This is common with brake fluid left for too long without being changed.

Addressing dark brake fluid: required actions

Dark brake fluid can indicate the potential issues within your vehicle’s braking system. Addressing this can prevent costly repairs and maintain the safety of your vehicle. We have shared the action guide on how to tackle the issue of black brake fluid:

Step 1: Regular inspection

Visual check: Regularly inspect the brake fluid reservoir to monitor the condition of the brake fluid. It’s a signal to take further action if it appears dark or murky.

Scheduled service: Adhere to the scheduled service intervals mentioned in your user’s manual. These services often include checking the brake fluid condition.

Step 2: Consult a professional

Seek expert advice: If you suspect the brake fluid is deteriorating, consult a professional mechanic for an in-depth analysis.

Fluid analysis: In some cases, the mechanic may suggest a brake fluid analysis to check for moisture or other contaminants.

Step 3: Brake fluid replacement

Drain the old fluid: If the fluid is confirmed to be in a bad state, the first step is to drain the old, dark fluid from the system.

Flush the system: After draining the old fluid, the brake system should be flushed thoroughly to remove any residues and contaminants. Fill the brake system with fresh, high-quality brake fluid per the manufacturer’s recommendations.

Step 4: System check

Inspect brake components: With changing the fluid, have the mechanic inspect the brake lines, calipers, and other components for wear and tear or potential damage.

Replace worn-out parts: If any components are worn out or damaged, replace them to prevent further issues.

By doing regular inspections, consultations with professionals, and timely fluid replacements, you can ensure the longevity and functionality of your braking system. Follow the below YouTube video too.

Can you drive with dark brake fluid?

No, you cannot drive a vehicle with dark brake fluid. Although many motorists risk this and ignore expert advice, avoid falling into the trap. This fluid warns you that you need to correct the situation. Black brake fluid has the potential to corrode metallic parts. This means that even the brake pads will eventually give in. Dark brake fluid renders the brakes ineffective.

You will be forced to pump the brakes several times during emergency braking. Your stopping distance will be increased. The risk is too much. According to experts, bad brakes cause around 20 percent of global traffic accidents. The components of these brakes can even be in good condition. But some of these could be using dark brake fluid. Such accidents usually occur as rear crashes.

How often should brake fluid be changed?

The frequency of changing brake fluid varies with manufacturers. But as a rule of thumb, you should change it at least every two years. Whether the distance covered has reached a given target or not. Just change it. This is one way of looking at it with safety in mind. Other experts recommend that you should change the brake fluid after around 60,000 kilometers. If you see discolored brake fluid in the system, change it. Always abide by the manufacturer’s recommendations.

What happens if you never change brake fluid?

If you do not change the brake fluid, it will continue losing its strength. Over time, it will damage your brake caliper and cause heavy corrosion. This means that you will lose the brakes. As you apply those brakes, the pedals will feel weak. When you drive such a vehicle, you can easily cause a severe accident.

Can I just put new brake fluid in?

No, you cannot just add new brake fluid. There is a process you need to follow. First, you must remove the old one and flush the system. Then you can go ahead and add the new brake oil. This way, you will allow the brakes to give you the best performance. Do not ignore the brake fluid’s dark color by adding blindly. It will not perform reliably. The only exception to this is where the brake fluid is new. This only requires topping up.

Add brake fluid

What happens if you mix old brake fluid with new?

You cannot mix old brake fluid with the new one. If you do this, the new brake fluid becomes contaminated with the old one. When used, the brakes on light vehicles should apply 30 to 40 bar pressure. This is an average value and does not apply to old brake fluid. But it shows that mixing can compromise a percentage of your braking system.


Is dark brake fluid bad? Do not allow your vehicle to run with it. For many years, it has led to the loss of lives, damage to equipment, and destruction of the same cars beyond recovery. Mixing the old brake fluid with the new one is no need. Always remove the old fluid before putting in the fresh one.


Mr. Shafiqule Islam is a graduated Mechanical Engineer and has more than 15 years experience of repairing and maintenance of different brand vehicles like Toyota, Mitsubishi, Ford, Mercedes, BMW etc. He is also giving training to Mechanics. He has started writing to share his practical knowledge to Vehicle Owners, Drivers and Mechanics to keep their cars at best fit.

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