When is the best time to change the brake fluid? Is it necessary to change the brake fluid?

Brakes are one of the most important parts of a car that cannot fail. Once the brakes fail, it can cause a serious traffic accident. Sensitive brakes allow us to brake quickly when a dangerous situation is about to occur. Brake fluid has a certain impact on brake performance, so brake fluid must also be replaced regularly.

When is the best time to change the brake fluid?

Generally, you can use a brake fluid test pen to test the water content. The method is very simple, just open the lid of the brake fluid tank, insert the test pen, and observe the indicator light. Generally, the water content of the brake fluid is often less than 2% in the first year, so it does not need to be replaced. In the second year, the water content of the brake fluid may reach 3% or exceed 4%, and it needs to be replaced. It usually takes two people to replace the brake fluid. Pay special attention to exhausting all the air, otherwise it is easy to cause the brakes to fail.

Because our cars are used in different areas, the water content of the brake fluid will vary greatly. For example, if we often drive in humid areas and park in a relatively humid underground garage, the water content of our brake fluid will increase significantly. Therefore, we should use a brake fluid tester to detect it most accurately.

Is it necessary to change the brake fluid?

The reason why brake fluid needs to be replaced is mainly because brake fluid is hydrophilic. If the water content is high, the high temperature during braking will vaporize it and cause air to remain in the pipes, reducing braking performance.

After long-term use of brake fluid, moisture in the air will enter the brake fluid. When the brake system is working, it mainly relies on the friction between the brake pad and the brake disc to brake the vehicle. During the friction process, the temperature of the brake system is very high and is transferred to the brake fluid. The water in the brake fluid will evaporate into water vapor. Too much water vapor means that gas is stored in the brake fluid, and the braking stroke is significantly increased, which can easily lead to brake failure.

Therefore, the brake fluid needs to be replaced after long-term use.

The best standard for brake fluid replacement is based on the water content in the brake fluid. This is mainly because China is a vast country with different weather conditions in different places. Some areas are close to the sea or are often rainy, the air humidity is high, the moisture in the air increases, and moisture can easily enter the brake fluid; but some places in China have long periods of drought and little rain, and the air is abnormally dry. In places like this, the moisture content in the brake fluid is naturally less!

What is brake fluid?

Brake fluid is also called brake liquid. Currently, synthetic brake fluid is used. Synthetic brake fluid can be divided into alcohol ether type, ester type and silicone oil type. The most commonly used are alcohol ether type and ester type. Brake fluid is good, with low freezing point, high boiling point, good stability, and not easy to corrode rubber and metal pipes. The brake fluid required in the market is DOT 3 and DOT 4, and a small number of models will use DOT 5.

Brake fluid is generally a mixture of alcohol (DOT3) and alcohol and lipid (DOT4). Alcohols easily absorb water, and once absorbed, it is easy to lower the boiling point of the brake fluid. In this way, during high-intensity braking, the water in the brake fluid may be vaporized, resulting in air blockage, which may cause the brakes to fail. Therefore, DOT4 is commonly used in modern times. DOT4 has lipids added to it, and its water absorption has been greatly improved. DOT4 and DOT3 are compatible with each other, and DOT4 can generally replace DOT3.