To add brake fluid to a vehicle, clean the reservoir cover, open the reservoir, check the fluid level and fill the reservoir to the indicated level. If the vehicle is equipped with an antilock braking system, check the owner's manual for special instructions before opening the cap.
- Clean the cover
Use a clean rag to wipe the cover of the reservoir tank clean before opening it. Doing so prevents small amounts of dirt from falling into the reservoir and causing failure of the master cylinder.
- Open the cover
If the vehicle has a plastic reservoir, unscrew the cap. Older vehicles have a metal reservoir that requires using a screwdriver to pry the retaining clip to the side before opening. Close the cap quickly after checking and filling the tank, as the fluid absorbs water from the atmosphere.
- Check the level
The level should be within half of an inch of the cap. With plastic reservoirs, keep the level between the minimum and maximum marks on the side of the tank.
- Fill the tank
If the level is low, add brake fluid from a sealed container. Bleed the brakes before driving the car if the reservoir is empty. Have a mechanic change the fluid if it is dark colored.