When it comes to maintaining a safe and efficient car, one aspect that is often overlooked is the importance of the brake fluid in the braking system. A crucial component in bringing your vehicle to a stop safely, brake fluid plays a pivotal role in transmitting the pressure applied to the brake pedal into the actual function of slowing down your car. As such, ensuring that your brake fluid remains in optimal condition is of utmost importance.

Every time a vehicle comes to a complete stop, brake fluid, typically known as hydraulic fluid, is used. This fluid is necessary for the proper operation of the brakes, hence it must be maintained. The brakes of a car are operated by a variety of different components. All of the components of the braking system should be kept in good working order because it is one of the primary safety elements of an automobile. Well, in this article, I’ll be discussing the meaning, functions, types, replacement, and cost of brake fluid.

brake fluid

Ok then, let’s get down to business.


What is a brake fluid?

Brake fluid is a type of hydraulic fluid used in hydraulic brakes as well as hydraulic clutch applications in vehicles, motorcycles, light trucks, and some bicycles. It is employed to increase braking force and to convert force into pressure. Brake fluid is non-compressible, just like all hydraulic fluids. This means that the fluid in a vehicle’s brake line is forced to travel through the system when pressure from the brake pedal is applied at one end of the braking system.

This force is transmitted to a vacuum-powered brake boost, which then transfers it to the brake pads, which in turn press against the wheels of the car to stop it. Because of this, brake fluid is an essential part of your car. Anything that could decrease the fluid’s quality, including moisture absorbed from the air, would reduce its effectiveness and perhaps impair your car’s braking ability.

Functions of a brake fluid

Basically, without brake fluid, a car’s braking system will not function. To stop a car, the brake fluid converts the force of the depressed brake pedal into pressure and transmits this pressure to the front and rear brakes. Brake fluid is ideal for use in hydraulic braking systems since it cannot be compressed. It may function in conditions of high pressure and temperature, such as those produced when an automobile is coming to a stop.

Types of brake fluid

Here are the 4 major types of brake fluid:


The DOT 3 brake fluid is a polyethylene glycol-based fluid designed to withstand extremely low temperatures without thickening and extremely high temperatures without boiling. DOT 3 brake fluid typically boils at a temperature of about 250 °C.


The DOT 4 brake fluid is an efficient, non-petroleum automotive brake fluid that is designed for use in clutch and brake systems with traditional hydraulic brakes. DOT 4 fluids are recommended for such systems.


The DOT 5 is a silicone-based fluid. Fluid made of silicone is hydrophobic, which means that it repels water. The brake fluid is not contaminated when moisture is introduced to a braking system using DOT 5 fluid. This results in the moisture freezing or boiling, which can cause brake fade. Fluids made of silicone and glycol cannot be used together.

DOT 5.1

The brake fluid DOT 5.1 has an incredibly high wet boiling point of at least 180 °C and a boiling point of at least 260 °C, making it suitable for hydraulic brake and clutch systems. Particularly suitable for additional systems, such as ABS and ASR, due to the low viscosity at low temperatures.

The higher number indicates a higher boiling point, which is a critical factor in brake fluid. Do not forget that hydraulic fluids function due to their incompressibility. A closed system’s fluid is forced to move when pressure is applied, as opposed to contracting in volume. However, a gas behaves differently because it frequently compresses in reaction to external pressure.

As a result, it’s important that brake fluid stay liquid and avoid evaporating into gas. It also implies that if you’re going to be applying a lot of pressure to your braking system, which will likely cause it to become hotter, you might want to select a fluid with a higher boiling point, like DOT 5.

NOTE: The US Department of Transportation (DOT) assigns brake fluid a grade between 1 and 5.1. The boiling point of the fluid is indicated by this DOT number. The hydraulic fluid has greater resistance to high temperatures and performance environments the higher the DOT number, which also indicates better fluid quality. Nevertheless, you must use the brake fluid recommended for your vehicle. You can consult your vehicle’s owner’s manual or a professional to be sure of the brake fluid to use.”

Below are the major differences between DOT 3, DOT 4, DOT 5, and DOT 5.1 brake fluid in a tabular form:

differences between DOT 3, DOT 4, DOT 5, and DOT 5.1 brake fluid in a tabular form:

How often should you change brake fluid?

Every one to two years is the recommended interval to change your brake fluid, but it will also depend on the recommendation of the vehicle’s manufacturer. Moisture absorbed from the air is the most frequent threat. Due to the fact that water in brake fluid lowers its boiling point, it tends to lower pressure inside the braking system and reduces performance for the reasons stated above.

Also, some of the other parts of the braking system may start to deteriorate due to dampness. Brake fluid often turns from clear or light brown to a deeper color as it gets older. Cloudy-looking brake fluid may indicate that it needs to be replaced because moisture contamination can occasionally have the same effect. Also, you may always ask a professional to check the moisture content of your fluid.

Generally speaking, having your brake fluid changed by a qualified mechanic is better to trying to do it yourself. Old fluid needs to be carefully handled and must be thoroughly drained from the system. Also, it’s crucial to avoid mixing specific brake fluid types. For instance, the quality of a fluid based on silicon will deteriorate when mixed with a fluid based on glycol.

How do you tell when you need brake fluid change?

Here are 4 most common signs and symptoms you’ll notice when you need brake fluid change:

Spongy or Soft Brake Pedal

Does the brake pedal seem spongy, soft, or even bouncy when you press it? Does your car have to be stopped and slowed down by pressing the brake pedal all the way to the floor? You should change your brake fluid if this happens.

Air will enter the gaps in your brake line when the brake fluid level drops, resulting in soft brakes. It can be frightening and dangerous to drive with spongy brake pedals, especially if you don’t have them fixed right away.

ABS Light is illuminated

You may have a problem with your anti-lock braking system if the ABS dashboard light is on. In order to avoid skids and retain traction, this technology prevents your wheels from locking up during braking. The ABS system is automatically activated when the brake fluid level drops to help maintain your car stopping safely.

Ineffective Braking Performance

To keep you safe in an emergency, your brakes should be swift and sensitive. Your brakes need to be serviced if you have any delays or problems slowing down or stopping your car. These problems can indicate that you need to flush your brake fluid.

Warped rotors, worn brake pads, or a problem with another brake system component are some additional potential causes.

Another potential reason for ineffective braking is an underlying issue, such as deteriorated tire tread, shocks, or struts. A professional can examine your brake system and advise you on the necessary maintenance to improve brake performance.

Unpleasant Noises or Smells when Braking

If you hear odd noises when you brake, there may not be enough brake fluid in the system or there may be another problem. Grinding or scraping noises are frequent sounds. If you experience burning odors after hard braking, your brake fluid may have burned out.

In this situation, you should stop your car in a secure area and give it some time to cool down. Moreover, speak with a nearby mechanic to get advice and arrange for a service call. Driving with burned brake fluid may result in more severe problems, such as brake failure.

How do you check a brake fluid?

It’s incredibly easy and possible to check your brake fluid in almost any place. It’s crucial to keep in mind that brake fluid is hazardous and needs to be handled carefully. Use these quick methods to check the brake fluid on your car:

It’s crucial to remember that any kind of drop in the brake fluid in your car typically means that your brake system needs repair or that there might be a leak in your line. In either case, you should get your car and brakes checked as soon as possible.

How do you change brake fluid?

How do you change brake fluid?

Here’s a basic procedure for changing your brake fluid:

Gather necessary tools and materials:

To change the brake fluid, you’ll need a brake fluid bleeder tool, new brake fluid, and a catch container for the used fluid. For cleaning, you’ll also need rags or paper towels.

Locate the brake fluid reservoir:

This is frequently identified with a “brake fluid” label and is typically situated on the brake master cylinder. Be sure your car is levelly parked and that it isn’t running before moving forward, though.

Drain the old brake fluid:

The braking system should be bled by opening the bleeder valves located on each brake caliper or wheel cylinder using the brake fluid bleeder tool after removing the cap from the brake fluid reservoir. The old brake fluid will be drained in this way. Collect the used brake fluid next and store it in the catch container.

Change the brake fluid:

Drain all of the old brake fluid, then wipe the reservoir with a cloth or paper towel before adding the new brake fluid. Use only the brake fluid type that is specified in your vehicle’s owner’s manual.

Test the brakes:

After changing the brake fluid, it is essential to test the brakes to make sure they are working properly. Drive the vehicle while testing the brakes to ensure that they are responsive and not mushy. If everything seems normal, your brake fluid change is successfully completed.

Generally speaking, having your brake fluid changed by a qualified mechanic is preferable to attempting to do it yourself. Old fluid needs to be carefully handled and must be thoroughly emptied from the system. Additionally, it’s crucial to avoid mixing specific brake fluid grades. For instance, combining a fluid having a silicon basis with a glycol base will cause the latter to degrade.

What’s the cost to change brake fluid?

To ensure safety, changing the brake fluid or performing a brake fluid flush should cost between $80 and $130 and be carried out by a qualified mechanic. Depending on the sort of fluid you have and whether you want to change it yourself, these expenses may vary. Brake fluid generally costs between $6 and $39 per quart, mechanics bill between $150 and 210 per hour, and changing the brake fluid in the majority of cars would set you back on average $100.

Related Article


In conclusion, brake fluid is an essential part of a car’s braking system. It transfers force from the brake pedal to the brake components, ensuring a car’s stopping ability is both safe and effective. Vehicle safety depends on keeping brake fluid at the right quality and level.

According to the manufacturer’s recommendations, routine brake fluid inspections and replacements are essential to avoiding moisture contamination, corrosion, and a drop in boiling point. Brake failure and poor braking efficacy might result from neglecting brake fluid maintenance.

The relevance of brake fluid in overall vehicle safety emphasizes the importance of following a regular maintenance plan, taking care of any concerns right away, and using the right kind of brake fluid recommended for your vehicle. By doing this, you contribute to maintaining the dependability of your brakes and the safety of your driving.

That is all for this article, where the meaning, functions, types, replacement, and cost of brake fluid. I hope it was helpful, if so, kindly share it with others. Thanks for reading, see you around!