El brake fluid It is one of the fundamental components of a vehicle's braking system, and its function is crucial to ensure safe driving. Keeping the fluid in good condition and replacing it on time prevents possible brake failures that could compromise the safety of the driver and passengers.
In this article, we are going to detail exhaustively When should you change brake fluid?, as well as all the important factors related to its maintenance.
Brake fluid change frequency
Experts agree that, in general, brake fluid should be changed every 40.000 km or every two yearsThis is because the liquid loses its properties over time, especially due to its tendency to absorb moisture, which reduces its effectiveness. However, it is important to follow the recommendations of the manufacturer, as some car models may have different specifications. Therefore, it is essential to refer to the vehicle manual for accurate information.
Even if the 40.000 kilometer mark has not been reached, it is also recommended Check the condition of the brake fluid at every regular check-up or when the car is in the garage for any other maintenance. This ensures that the braking system is in optimal condition and problems resulting from fluid degradation are avoided.
Importance of changing brake fluid
La Importance of changing brake fluid The problem is that this hydraulic system is designed to operate under high pressure and temperature conditions. Over time, the liquid tends to absorb moisture, which is unavoidable due to temperature fluctuations and the condition of the braking system components. This moisture can seriously affect the effectiveness of the system, as water has a much lower boiling point than brake fluid.
When there is a significant build-up of moisture, vapour bubbles can form under persistent braking or when subjected to high temperature conditions. This can lead to a failure in the braking system, as vapour is highly compressible, unlike liquid, which can lead to the vehicle not braking properly. In addition, moisture can cause corrosion in the internal parts of the brake system, which considerably increases the risk of breakdowns.
Brake fluid characteristics
El brake fluid used in cars has specific properties that make it suitable for its function. Its main characteristics include:
- High boiling point: Brake fluid must remain stable at high temperatures, typical of intense braking conditions.
- Minimum compressibility: Unlike other fluids, brake fluid cannot be compressed. This allows any pressure applied to the brake pedal to be transferred directly and immediately to the wheels.
- Hygroscopicity: This type of liquid has the ability to absorb moisture from the environment, which, although it is an inevitable characteristic, leads to its progressive degradation.
- Anticorrosive properties: It must be compatible with materials such as rubber and metals that make up the brake system to prevent them from deteriorating.
Types of brake fluid
There are different types of brake fluid, classified mainly by their boiling point and composition. According to the standard DOT (U.S. Department of Transportation), these are the most common types:
- DOT 3: This is the most basic and economical type, with a boiling point of 205ºC when dry and 140ºC when wet. It is mainly used in low-end vehicles or conventional brake systems.
- DOT 4: More heat resistant and with greater moisture resistance capacity. Its dry boiling point is 230ºC and wet boiling point is 155ºC, making it suitable for most modern vehicles.
- DOT 5: Synthetic (silicone) based, used in vehicles with highly demanding systems, such as sports or racing vehicles. Not compatible with DOT 3 or DOT 4.
- DOT 5.1: Also based on glycol, it has a boiling point above 260°C and is used in vehicles with advanced features, such as those equipped with ABS systems.
How to check the condition of brake fluid?
To ensure optimal performance of the brake system, it is advisable Regularly check the level and condition of the brake fluid. You can do it in the following way:
- Locate the tank: It is usually found in the engine compartment, with a cover usually identified with symbols reminiscent of brakes.
- Check the level: The tank will have a minimum and maximum level indication. If the level is below the minimum, it needs to be topped up or a garage should check for leaks.
- Check the color: A good brake fluid is usually clear or amber in color. If it is dark or brown, it may have degraded and needs to be changed.
It is important to remember that brake fluid is corrosive, so it is advisable to handle it carefully and avoid it coming into contact with other parts of the engine or the bodywork.
How to change brake fluid
Changing brake fluid on your own can be a complex task and, while not impossible, it does require the right knowledge and tools. For those who are comfortable with this type of maintenance, here are the basic steps:
- Raise the car on a flat place: It is essential to prevent the car from sliding and to have good access to the brake system.
- Drain the old fluid: Use a syringe to draw the fluid out of the reservoir and collect it in a container.
- Refill with new fluid: Use the type of fluid recommended by the manufacturer and fill the reservoir to the proper level.
- Purge the system: This process consists of removing all the air from the braking system, a process that is carried out with the brake pump. It requires technical knowledge, so to do it properly, it is recommended to go to a workshop or use specific tools.
However, it is best to go to specialized mechanics that they have the appropriate machinery to properly purge the system. This ensures correct operation and prevents any risk of accident.
It is important to remember that the time and investment spent on this maintenance is a small fraction compared to the risks associated with losing braking effectiveness.
When you don't need to change brake fluid
Most manufacturers recommend changing the brake fluid, but it will not always be necessary if the vehicle has traveled very few kilometers and has not been exposed to severe humidity conditions. However, even if the suggested mileage has not been reached, it is essential to perform a brake fluid change. Periodics inspections of the state of the liquid.
A fluid in good condition will maintain its amber color and will not show signs of evaporation or contamination. If the fluid is found to be still in good condition, the change can be postponed, but never beyond the fourth year.
The performance of your vehicle and the safety of its occupants depend largely on the good condition of the braking system. Preventive maintenance can make all the difference in an emergency situation.
Therefore, keeping the brake system and its fluid in optimal condition is a security obligation which should not be taken lightly. Always consult a professional mechanic if you have any doubts about when to change the oil and make sure you always use the correct fluid.