Bottom Line Up Front - change your brake fluid regulalry

I've been doing my own mechanical work on my cars (including brakes) for 30 years. This is the first time I've ran into this problem. When the brake pad wear sensor light came on, I replaced pads front and rear. The old pads were very thin. The new pads (ceramic) were uber thick. I used a c-clamp to squeeze the front caliper pistons all the way in and pryed the rear pistons (one at a time) all the way in to get the new pads to fit. I did not open any bleed valve or line hose. Of course the master cylinder over-ran due to the large amount of fluid being squeezed out of it. No prob, just rinsed and cleaned it up.

Took it for a test drive and noticed right away the pedal went to the floor and there was very little braking. Pedal was soft and spongy. It would stop, but would not come close to locking the brakes and a panic stop would be dangerous.

So I bled the brakes. The original fluid (2005) had never been changed and came out green. As far as I can tell, no air bubbles came out (used clear hose). Bled it until new clear fluid came out (1 pint). Brakes came back! Pedal was firm and impending lock-up caused ABS to activate.

So although it's baffling in that I'm convinced no air had been introduced, I feel the old brake fluid being pushed back the the M/C is the culprit. The oldest fluid is at the calipers (topping of at the M/C with new fluid over time). I am guilty of not changing it. But in the "old days", never had to. Did this same procedure many times over the years and have not had a problem. But listening to the "experts", nowadays they tell you to replace the fluid every year or 2. I used to blow them off as B/S. I'm now a believer.