ACE,

   If you want weathering 101, find a construction site with some Caterpillar dozers out there & go lookin' around at them. That's as good as it gets. You will also notice that  Rust never really collects on th trax that are in use. You may get some 1st. thing in the mornin' because of Morning dew, but that is quickly worn off once those Cats get moving around !! I work construction ( Commercial Plumber) & see those babies every day  &take notice. Even th Diesel Fuel stains that run down th side & get dust collected ,mixed into it before it dries !!

  ERIK