Many people usually only change the oil, antifreeze, transmission oil, etc. when maintaining the car. If such oil is not replaced in time, the parts will be damaged at most. The car breaks down and can be repaired, but there is a kind of oil that is often ignored, which will directly threaten our personal safety, that is brake oil!

Brake oil, also known as brake fluid, is the liquid medium that transmits brake pressure in the hydraulic brake system. The brake oil on the market now has a strong hydrophilicity. As time goes on, the water content in the brake oil will become higher and higher. Long-term braking or vigorous braking will vaporize the water, resulting in a decline in the brake performance, or even complete failure, which will seriously affect our driving safety.
What's the harm of not changing
It will absorb water and deteriorate over time
If the brake oil is not changed for a long time, the most important thing to worry about is that the water absorption deteriorates.
Because the main component of brake oil is alcohol-containing substances, it has relatively strong water absorption. The same is true for the ethanol gasoline we often say. Because it contains ethanol, it also becomes easy to absorb water and deteriorate.
Water absorption will lead to lower boiling point
The water content of brake oil increases, resulting in a sharp decrease in the boiling point of brake oil.
Simply put, the boiling point of water is relatively low: 100 ℃, beyond the boiling point, "popopo" becomes water vapor. Pure brake oil is so mixed that its original high boiling point is pulled down by water, reducing the overall boiling point.

According to a study by the National Highway Safety Administration (NHTSA), the boiling point of brake oil will be reduced by 8% when the brake fluid contains 1% water, 21% when the brake fluid contains 2% water, and almost 50% when the brake fluid contains 3% water.
Easy to produce air resistance
For brake oil, the higher the boiling point is, the better.
Because in principle, the temperature of brake oil will become higher and higher because of the brake and ambient temperature.

If we say that the boiling point of our brake oil is too low, "sizzle sizzle" originally has oil, and "sizzle" turns to smoke later and then disappears, which is easy to vaporize. The professional term is "producing air resistance".
Gases from vaporization occupy part of the space
As the gas generated by vaporization encroaches on a part of the space, when the piston is compressed to the limit, the established pressure is not enough, and the brake caliper is not clamped enough, and the brake is easy to fail.
Brake drag
In addition to brake failure, air resistance will also cause brake rebound problems and brake drag. The more the brake oil absorbs water, the greater the air resistance, the more the piston cannot return to its original position, and the more obvious the brake drag.

Brake drag not only wears the brake pads, but also is not conducive to the next brake.
Therefore, if we don't change the brake oil all the time, it will seriously affect our driving safety.
How often is it replaced?
The brake fluid is golden, a little lighter than the oil color, and its consistency is also lower, which is closer to the appearance of water.
The brake fluid is usually changed every two years or 40000 kilometers. It may need to be changed in advance in wet places. The brake fluid will absorb water, which affects the braking effect.

The replacement time in the maintenance manual is different for different cars, some 30000 and some 50000. And the roads we drive are different. Is the traffic jam today? I won't block you. The best way is to determine the replacement time of brake oil through inspection, which is the most accurate.
We can use the brake fluid detection pen to detect, and the water content is more than 3%. I don't have one. I can find a tire shop and ask him to try it for us.

Not only can the brake fluid be mixed, but there are strict regulations on the type and brand of filling, which are directly written on the cover of the brake fluid. Look clearly before changing.
How to select brake fluid?
How should we choose the brake fluid?
Keep these indicators in mind:
Good viscosity-temperature property, low freezing point, high boiling point, high temperature resistance to "gas resistance"
I recommend this gallon of super advanced synthetic brake fluid, which is applicable to Benz, BMW, Volkswagen, GM, Toyota, Hyundai and other European, Japanese and Korean vehicle systems and construction machinery.

The equilibrium reflux boiling point exceeds 208 ℃, and the wet equilibrium reflux boiling point exceeds 150 ℃
High boiling point and high temperature have greater resistance to "air resistance" and better braking performance.
Excellent low temperature performance, good low temperature fluidity at - 50 ℃, long service life.
Advanced additive technology, comprehensive anti-corrosion protection.