Brake Fluid Maintenance – Signs It Needs to Be Replaced

What is Brake Fluid? 

Brake Fluid is Part of a Complex System

Brake Fluid is Part of a Complex System

Brake fluid is the bloodwork of your car’s braking system. It is a special chemical fluid typically composed of glycol-ether, which has a high boiling point. The high boiling point makes the fluid difficult to compress, which is what creates enough pressure needed to stop a car. Without this pressure and high boiling point, the braking system would be useless. That being said, brake fluid affects the entire brake system in complex ways. 

While there are different kinds of brake fluid, the average consumer only needs to worry about DOT 3. This kind of fluid works well for any cars used for commuting. 

Types Of Brake Fluid:

DOT 3 



DOT 5.1

The main differences and uses of each fluid vary depending on the application. Typically, race cars may require high-performance fluids (DOT 4 or higher) whereas DOT 3 is perfectly fine for average cars. The main differences are that DOT 3 and DOT 4 are glycol-based, whereas DOT 5 uses silicone. Some cars may require DOT 5 only, however, they will have a system that is specifically designed for that specific fluid. 

As a precaution, you should never mix brake fluids, especially DOT 5 with non-silicone based fluids. The resulting mixture can cause brake failure due to incompatibilities between mixtures. 

Professionals Know How to Change Brake Fluid

  Changing Brake Fluid is Complex, and Requires Years of Experience to be Done Correctly

Do you Need to Change Brake Fluid? How Often?

Yes. Despite the chemical nature of brake fluid, it is important to have it changed at least every two years. This is because even without an obvious loss of fluid (a leak), the fluid itself can go ‘bad’ overtime. Brake fluid is able to keep its properties intact while remaining in a sealed container, like the isolated system it operates in. However, exposure to open-air eventually allows for surrounding humidity to be absorbed by the fluid due to its hygroscopic nature. The word Hygroscopic simply defines an object’s ability to absorb moisture. 

Absorbed water reduces the compressing power of brake fluid by lowering its boiling point, which reduces the pressure it is able to produce. In short, water-contaminated brake fluid will bubble up quickly in response to heat, and the resulting gas will cause compression to occur. In other words, the gas bubbles detract from creating the pressure needed to stop a car or move segments properly. 

Can You Drive With Low Brake Fluid?

The short answer would be no. The consequences of non-operational brakes are disastrous, which is why this kind of maintenance should never be skipped. If you are driving, and only then notice that something might be wrong, it is best to see a professional as soon as possible. Low brake fluid indicates serious problems that can have sudden effects while you are driving, which can cause death. 

For instance, driving with low or contaminated brake fluid runs the risk of your brake system suddenly losing its function mid-drive, which can obviously lead to a car crash. 

How to Tell if Brake Fluid is Leaking

Sometimes a rapid change is brake performance can be indicative of another way brake fluid can deplete, and that is through leaking. A leak can occur from various parts of the system, though it is typical to come directly from brake lines through wear and tear. It is common to see semi-yellow puddles of fluid collecting under a vehicle. Fluid that appears dirty yellow signifies that the brake fluid is indeed old and needs to be changed. 

How to Tell if Your Brake Fluid is Low

While it is true that brake fluid will remain stable in an enclosed system, it will still deplete over time. This is because even the contained system is not exempt for building up moisture, which will slowly be absorbed over the course of two years. Other than the signs of leaking brake fluid, most tell-tale signs are based on brake performance. The following warnings may also occur:

ABS Symbol Light On

 ABS Lights Will Remain On if There is a Problem With your Brake System

ABS Light

The ABS light (anti-lock braking system) is a feature of all modern cars, manufactured for the purpose of preventing wheels from ‘locking’. The ABS system monitors your car’s wheel speeds and braking system and will kick into action when needed. If the ABS light is on (glowing bright yellow or orange), it is a sign that the ABS is not active for your system. Running a car without this system means putting yourself in unneeded danger, which is why it is best practice to have it checked out as soon as possible. 

Difficulty Pressing the Brake Pedal

Some problems surrounding low brake fluid can be noticed by a significant change in your brake pedal. Specifically, a pedal that is suddenly harder to press down on, or one that falls completely to the floor indicates serious problems. 


Low brake fluid will impact the systems surrounding it, which is why it is common to hear strange squealing noises. Normally these can alert other potential problems, however, it is best to check with a mechanic regardless. 

Burnt Smell

Heat generated by braking will eventually cause depleted or contaminated fluid to evaporate due to the loss of boiling point. The resulting reaction can leave behind a very chemical, almost burnt smelling fume. 

How Brake Fluid is Changed- 

When taken to a mechanic, a process known as ‘bleeding the brakes’ is done to completely flush out any old or contaminated fluid from the brake system. This process is done by pushing new brake fluid into the lines from one end of the caliper to the other. While pumping the brake pedal, new fluid enters the lines and forces out any older fluid left behind. 

It is important to note that when it comes to changing fluid, you should only use the same type of fluid that was previously in the system. So if you are changing brake lines containing older DOT 3 fluid, then only displace it with newer DOT 3 fluid. Some cars or vehicles 

Can You Change Brake Fluid Yourself?

When it comes to replacing anything in a car, remember that each part of your vehicle has a significant impact on other parts. Trying to replace brake fluid is possible to do by oneself, however, it requires years of car-repair experience to do correctly. It may be better to get a professional who is equipped with the right tools to do this during other routine procedures like changing your oil. Always remember that playing with brakes often ties in with playing with life, and any mistakes can result in the loss of it.