Why is it essential to change the brake fluid when replacing a damaged brake line?

Changing the brake fluid when replacing a damaged brake line is crucial to ensure optimal braking performance. Brake fluid is hygroscopic, meaning it can absorb moisture over time. When moisture enters the braking system, it can lead to various issues such as reduced boiling point of the fluid, which might cause brake fade during heavy usage, and corrosion of internal components of the brake system.

By replacing the old brake fluid, you are ensuring that the braking system operates at its best, providing reliable and responsive braking performance. This is especially important after replacing a brake line, as any potential moisture or contaminants that could have entered the system during the damage may affect braking efficiency. Fresh brake fluid maintains the necessary hydraulic properties required for effective braking, thus enhancing safety and vehicle control.