i used it (rain-x)during the slushy spring and works great,,,also keeps bugs off to some degree.
but must be used once a month,,,

\'52 Chevy, 3/4-ton, daily driver
'59 GMC 1/2-ton,
'59 Chevrolet 1/2-ton,
http://community.webshots.com/user/manitoban2005