I always remove the ball mount when not in use. Magnesium Chloride and gravel with salt can be used on our Interstate between September 1st and May 31st, not to overlook normal rain, fog, and snow. A painted shank and the adapter will rust together inside the receiver hitch. Once these items have been used to tow a trailer there's usually plenty of bare metal exposed from the force of the trailer's tongue weight to wear the paint off of the receiver hitch, shank, and adapter. At least leaving the receiver hitch open allows moisture to drain and dry. Otherwise, use a heavy hammer to remove once they're rusted together.