Paint protectant like Diamond Kote requires reapplying every 5 years or so. If you do not reapply, it will leave a haze on top of your paint job and no amount of waxing can eliminate it. I did some research on the internet on this topic and on rust protection. Basically, it says that car manufacturers these days have done so much to protect their car from UV and rust that it is not necessary to spend money on aftermarket products. For example, undercoating is not necessary because manufacturers use a dipping technique to coat their underside panels and thus permanently seal their parts. Other research found that improperly applied undercoating actually does more harm than good on the car. So, save your money and even if you are going to get it done. Don't get it done through the dealer. All they do is drive your car to the same guys who are doing the paint protection job and charge a high margin for it.
Regards,