fishycomics - You had said -
"Yes, brake fluid levels in the master cylinder will go down as brake pads wear, however we don't use this method for determining brake pad wear. To do that we must remove the wheels of the car for a visual inspection of the brake pads.
Then you said -
When brake fluid in the master cylinder drops, no matter where that level is showing on the master cylinder reservoir, be it just a bit lower than the full line or at the minimum line, etc., it matters not as this can indicate the presence of a brake fluid leak. The, "Minimum", line doesn't mean everything is just fine and there's no need to worry. It means that's the lowest the brake fluid level can be without the master cylinder potentially drawing air into the brake hydraulic system, which can lead to a soft brake pedal and a crash.
If the brake fluid level in the master cylinder drops it should always be immediately investigated to find out why that level has dropped. With brakes being such a critically important safety item, it is very important to diagnose any drop of brake fluid level in the master cylinder. Our very lives are dependent on properly functioning brakes.
Take care and have a good one. :thumbsup: