Would say my 29 year old sierra is proof waxoyl works as there's not a spot of rust on it so the best thing I can suggest you do is wire wheel any areas with surface rust and primer and paint them and then wack waxoyl over them areas my car has been outside for 29 years never garaged except for the last 4 months don't just put waxoyl over surface rust as it won't work/help. Main areas to do are cills battery tray corners in engine bay insides of doors without blocking water drain holes etc