I recently did the brakes and rotors on my 1995 940 front brakes.

Because the pistons were very hard to push in, I became concerned that there might be some issue with the calipers sticking.
The car seems to drive and brake fine.

Seemed logical that to test it, I should just jack up the front and see how the wheels rotate. I did, and both wheels rotate quite easily, just one can hear a very slight sound as the caliper brushes the rotor at a point during each rotation.

Question: Is this normal? Or should the calipers not touch the rotor at all with wheel rotation?

Also, if the piston is to be lubricated... what's the best thing to use? Anti-squeal lubricant? brake fluid? WD-40? (which contains silicone) I'd think that anything with silicone wouldn't be a good idea with DOT 4.

Thanks for any input...