with the wiper blade in the park position having the blade off the windshield reduces the possibility of the blade being ripped off when/if the ice freezes the rubber blade to the glass. this is why you can lift the blades in the full up position to avoid blade damage. my 1996 the blade sets on the windshield and if a snow / ice storm hits before starting I must be sure to have the wipers OFF. with the newer vehicles I have heard of the wiper system being damaged more than the rubber blade.
Originally Posted by martym