The reservoir has a transparent body, so the brake fluid level can be controlled from the outside.
The brake fluid level should always be closer to the mark «MAX».
If the brake fluid level is too low, before removing the cap from the expansion tank, wipe the cap and the area near the cap from dirt with a clean rag to prevent dirt from entering the hydraulic circuit of the brakes.
Add the recommended brake fluid to the reservoir. Mixing different types of brake fluid can damage the hydraulic system.