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How Often Should I Change Brake Fluid?

If engine oils are essential for your car to keep running properly, then brake fluid is what you need when your car has to stop. Every time you step on the brakes, brake fluids apply pressure on your car’s braking system, forcing the wheels to slow down.

But while there are numerous articles talking about general car service and engine oil, not many focus on brake fluid. This is why many people do not know whether brake fluid must be changed and, if so, how frequently.

Don’t worry: this article will answer all your questions about brake fluids.

What is brake fluid and what does it do?

Car brake fluid belongs to a class known as hydraulic fluids. As their name suggests, they are mainly used in hydraulic systems to transfer power. In modern motor vehicles, the braking system is hydraulic and therefore needs this car brake fluid to operate.

When you press down on your brake pedal, brake fluid is pushed down onto the pads on the rotors (or discs) on your brakes. Since fluids do not get compressed, the pressure is transmitted without any loss. The rotors are attached to your wheels, so the more you press, the more the brake fluid pushes against the rotors and the more your wheels’ rotation slows down.

What are the different brake fluid classifications?

The most common hydraulic brake fluid classifications are called DOT 3, DOT 4, DOT 5 and DOT 5.1. All three types are made from substances called glycol ethers.

The difference between them lies in the additives included by the brake fluid manufacturer. These give brake fluid some other properties, such as anti-corrosion, increased stability, etc.

Brake Discs on Car

Should brake fluid be changed?

The hydraulic braking system of your car is a closed system. So, in an ideal world, nothing in the system comes into contact with the outside. In such a scenario, brake fluid will never get used up. So, in theory, you never need to replace brake fluid.

But if that is the case, why do car manufacturers ask for a brake fluid change every so many years? The answer is because no system is ever perfect.

Yes, brake fluid exists in a closed system, but other parts of the apparatus, like pipes and pads, can deteriorate over time. When this happens, air and water can enter the system and mix with brake fluids.

This reduces the boiling point of the fluid, making it evaporate into steam, creating water vapor. This can prevent your car from braking properly.

Further, the additives in brake fluid also expire over time. When this happens, they no longer provide protection against corrosion or rusting. This is yet another reason why brake fluid should be replaced.

How often should brake fluid be replaced?

Many car manufacturers recommend that brake fluid be replaced once every 2 to 3 years. Your car manual will be the best guide here.

Further, if you live in a very humid and hot region, it is easier for water vapor to get into the braking system, weakening the brake fluid. Because of the high humidity, it is recommended to get your braking system tested at least once every two years.

If you are not sure, just visit your nearest authorized service center and ask a qualified mechanic. They will guide you on whether your car brake fluid needs to be replaced or not.