What are the reasons for the soft brake pedal after brake fluid replacement?

[LilahRose]

The reasons for the soft brake pedal after brake fluid replacement are: 1. Inferior quality of brake fluid; 2. Residual air in the brake system. The functions of brake fluid are to transmit energy, dissipate heat, prevent corrosion and rust, and provide lubrication. Its characteristics are: 1. Good viscosity-temperature performance, low freezing point, and excellent low-temperature fluidity; 2. High boiling point, no vapor lock at high temperatures; 3. Minimal quality changes, not causing corrosion or deterioration of metal and rubber components. The method to determine the quality of brake fluid is: Check the viscosity and color of the brake fluid. Brake fluid that is thin, colorless, and transparent cannot be used. Qualified brake fluid is light yellow or dark yellow in color and spreads slowly when poured onto a glass plate.