Originally Posted by
Barabaika
I think that the calipers can be shot only if they cracked. Highly unlikely.
Incorrect. Calipers usually fail when they no longer open or close smoothly and with enough force to push both arms away from the rim. It's easy to see if it's the cable/housing or if it's the caliper. Simply disconnect the cable and push the calipers close and feel it.
Calipers should be oiled, especially if you are riding it through winter. It is hard on everything on your bike.