Continue flushing the brake lines as described above until you see the new brake fluid coming through the bleed tube.

The new brake fluid will be a lighter color than the old, discolored brake fluid.

Keep an eye on the master cylinder. If the fluid level gets too low again, be sure to add more fluid.

When you are seeing new brake fluid coming through the bleed hose, stop the flushing process and firmly close the bleed valve.

Gently pull the bleed tube off of the bleed valve and re-cover the valve with the little rubber cap.