When using a car with a trailer and frequent trips on mountain roads, the brake fluid must be changed every 15,000 km.
We pump out the old liquid from the tank with a syringe or a rubber pear.
Pour new fluid into the reservoir.
Bleeding hydraulic brakes (see Bleeding the hydraulic drive of the brake system) and clutch (see Clutch bleeding) until the new fluid (lighter than the old) will not begin to come out of the bleeder valves of all working cylinders. After bleeding the brakes and clutch, we bring the fluid level in the reservoir to normal.
Use brake fluid recommended by the manufacturer. Otherwise, failure of the brake and clutch hydraulic drives is possible.