Brake master weeping

Disc masters have a large bowl and a small bowl. The large bowl is for the disks. As pads wear out, the disk piston rides closer to the rotor to compensate for the wear. This makes the "hole" behind the piston bigger, and is filled with fluid. So in essence, fluid is replacing the volume of pad wearing away. That's why you need more fluid.

Check the joint between the master cyl and the booster (PB), or Firewall (MB). Sometimes fluid leaks past the master cylinder piston.