market dynamics
On the problem of motorcycle brake oil, you will know how to replace it after reading it. 刹车油分DOT3/DOT4/DOT5三种标准
Release date:2024.04.11

First, how to choose the motorcycle brake oil?

Brake oil is divided into DOT3/DOT4/DOT5 three standards, popular points to say that the meaning of these three numbers is only their integration with water, and DOT5, the lowest water integration, completely does not absorb water. DOT3 has the highest water solubility and good water absorption. The dry and wet equilibrium reflux boiling point of DOT3 is the lowest, and DOT5 is the highest.

Based on this feature, the replacement cycle of DOT5 brake oil is the shortest, the replacement cycle of DOT3 is the longest, and the replacement cycle of DOT4 is in the middle of the two. So why does absorption and non-absorption lead to the length of their replacement cycle? This is because when the brake pump is designed, it must be communicated with the atmosphere, and the atmosphere contains a lot of things, one of which is water. After water enters the brake pump and oil together, because the boiling point of water is extremely low, this part of the water that cannot fuse will lead to a rapid decline in brake performance.

In between, the brake oil of the general small road motorcycle or electric vehicle is the use of DOT3 standard. Motorcycles with more than 250cc displacement and double piston brake calipers generally use DOT4, and DOT5 is generally used very little.

Second, why should the brake oil be replaced regularly?

To understand this problem, we must first understand the dry and wet equilibrium reflux boiling point of brake oil.

Dry boiling point: refers to the boiling point of the brake oil when it is just added to the brake system, at this time the brake oil has just been added to the brake tubing, and it will not inhale water, so users can understand this value as the boiling point of the "new product" when the brake oil is just used.

Wet boiling point: This value refers to the boiling point of 3.5% moisture after 2 years of brake oil use, which can be understood as when our brake oil is used for 2 years, due to the inhalation of a certain amount of water, resulting in the dry boiling point of the brake oil "new state" has attenuated, and this value is the "boiling point" value after attenuated. (Actual driving conditions often exceed 3.5% water content)

Brake oil in high intensity operation because the temperature continues to rise will make brake oil boil, produce bubbles affecting brake performance, then the higher the boiling point of brake oil theory has a better high temperature performance, but the boiling point of the value is not static, with the extension of the use of time, the brake oil will more or less absorb a certain amount of water, which will reduce the boiling point of brake oil. Therefore, according to this characteristic, the industry body has double index requirements for the boiling point standard of brake oil.

The national standard requires that the minimum dry boiling point of brake oil should not be less than 205℃. The minimum dry boiling point of DOT3 standard brake oil should not be ≤205℃, the minimum wet boiling point should not be ≤140℃, the minimum dry boiling point of DOT4 standard brake oil should not be ≤230℃, and the minimum wet boiling point should not be ≤155℃. According to these characteristics, we can deduce two points: heavy motorcycles will produce higher friction temperature when braking. So use wet and dry brake fluid with a higher boiling point. In addition, more than 2 years of brake oil due to excessive moisture, will cause the phenomenon of wet boiling point reduction, affecting brake safety, so it should be replaced regularly.

Three, found that the brake oil is less, directly add a little why not?

Many owners find that their motorcycle brake oil is less, they casually add different kinds of brake fluid, which is extremely wrong, different types of brake oil mixed, will lead to brake fluid stratification, boiling point reduction, corrosion brake bowl, directly affect the brake performance! The correct way is to discharge all the original brake oil and replace the specified standard brake oil of the vehicle.

Fourth, what is the composition of brake oil? Does it matter if it spills on the tank?

DOT3 and DOT4 brake oil is a non-mineral oil system, based on polyglycol and glycol and glycol derivatives of alcohol ether synthetic brake fluid, and then add lubricant, diluent, rust inhibitor, rubber inhibitor, etc., the combination of water absorption and moisture absorption is very strong, so there will be a "wet boiling point" index, brake oil needs to be used once opened. So as not to absorb moisture in the air and deteriorate. Even if stored, it should be strictly sealed. If brake oil spills on the fuel tank or paint, clean it up in time to avoid damage to the paint.

Five, we recommend to follow the following three principles when buying brake oil:

1. Try to choose the products of big brands such as Mobil, Shell, Castrol, BOSCH, Gator Depot, etc., or choose the domestic brands designated by the original factory, do not choose unfamiliar brand products that have never been heard of.

2, do not choose the price is too cheap products, the current DOT4 brake oil according to the brand, the market price per liter ranges from 30-80 yuan, some big brand products even more than 100 yuan. If you encounter brake oil that is much lower than the above price, you should keep an eye on it. Tens of thousands of kilometers to change, is it worth saving tens of dollars to risk your life?

3. The color of the brake oil is generally light yellow or dark yellow, and the friction after dropping on the palm will become more and more hot, and the brake oil that is too thin or completely colorless and transparent is recommended not to risk being used.

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