The BEST chassis application that I have found is a product called "Chassis Saver. It applies like POR 15. All you need to do is wire-brush your frame,wipe it down with lacquer thinner,and apply the product. It is widely used on commercial and municipal applications,such as snow-plows,and related equipment,exposed,and used in adverse weather conditions,especially under corrosive (road-salt)conditions.This product is manufactured by a company called "Magnet". There is a video,on "Youtube" of this product being applied to Ted Nugent's 4X4,since the weather in Michigan did a "number" on it.go to
http://magnetpaint.com This product has been tested and proven very durable,for at least 10-years. I painted my frame rails,axles and springs 3-years ago,and the only rust showing is the leaf springs,because of the constant friction. I am VERY pleased with this product! The other GREAT part of "Chassis-Saver" is,it is one-step.no need to prime,or top-coat! You may top-coat,if you wish to,though. The mfr. states that the coating is not affected by U.V. rays,although the coating will turn from satin black,to dull gray,over time. Hope this helps.