Tight caliper pistons and brake fluid

brakes
nissan
frontier

#1

I had the front end of my truck jacked up and noticed both wheels were hard to turn. The pistons in the calipers were tight and I replaced the calipers. In the old days of brake fluid, the fluid got darker each year and then black and then black with sludge at the bottom so I used to regularly flush the fluid. Then I noticed brake fluid must be more advanced because it doesn’t get darker each year so I quit flushing it.

My question is, did old but clear brake fluid cause the pistons to stick?


#2

Brake fluid attracts water, water rusts the caliper piston bore, water is clear.