Brake oil has been used for a long time, although it does not have much influence on the surface, but when the vehicle is in emergency braking or driving downhill for a long time, the problem is easy to appear. The brake system will cause the brake oil temperature to rise rapidly during long-term or emergency braking. The brake oil itself has strong water absorption characteristics, it will absorb the moisture in the surrounding air, such as car wash, humid air, etc., there will be moisture infiltration, the accumulation of water into the brake oil will directly cause the boiling point of the brake oil to drop, make The power will drop. At the same time, it will cause air resistance in the brake pipe, which will affect the performance of the brake. In addition, moisture can also corrode the brake circuit, resulting in damage to the internal valve of the anti-lock brake (ABS) hydraulic assembly, which seriously affects the transmission response of the brake. Moreover, the brake oil has been used for a long time, and the leather cup and the piston in the brake pump are worn out, causing the brake oil to be turbid. Brake oil is usually replaced once every 2 years or 6W kilometers.