Mine also lives in an unheated garage and the exterior looks pretty new. I cover the woodbox lid and the floor with Extra-HD foil. There is no "heat shield" in this smoker, unless it's what you call the woodbox. I don't clean the sides and I do let the grease accumulate in the drip pan, which isn't lined (yet!). I clean the racks pretty thoroughly just before a smoke, so they don't gather dust or rust, and I spray them with Crisco Pan Release just before each use (makes the cleaning SO much easier!). I don't recall a recommendation for wiping the sides down after every use, and in fact I do remember many recommendations to leave the walls dirty for flavor!