2015 GMC 2500 Base/WT Crew Cab
I just bought this last month. It came from NV and absolutely rust free. Being in Michigan I knew it needed rust proofing immediately. I decided to go with Krown rust proofing. It is the oil. They spray the underbody as well as cavities throughout the truck. After researching it seemed like the best option available to me. $150 per year. I thought of doing Ziebart, but with its initial cost and yearly touch ups it would take 8 years of Krown applications to equal the same cost. The way I attract deer I doubt I make it that far.
Also, I live on dirt roads and it seemed some of the other products don't hold up to gravel.
One thing I made sure I did is put my new step bars on before I took it to get sprayed. They sprayed them too to keep them rust free.