I just bought and tried the NHOU product this past fall, I haven't had it on there yet long enough to tell if it will live up to the hype. I bought a 5 gallon bucket of their black stuff and their estimate was 6 quarts for a 1st time application, I used 10. (1/2 of the 5 gallon bucket) and I didn't get to pull the door panels or the tailgate access panel and get inside those like I wanted to.
Luckily we here In the Chicago area have had a mild winter, not as much salt used to this point as A typical winter.
And every time I thought they "might" I have left it parked (outside on a concrete driveway) and took my beater Dakota that's already beyond hope anyway.... But I hope it does as they say. The truck I put it in, is a 12 ram 1500 reg cab long bed, former Fastenal truck. I still owe 3 years in a 4 year loan and as expensive as trucks are I sure hope it does as they claim
I removed the plastic fender liners, the tail lights and blew out all the leaves and such that I found hiding beneath all that and all the dirt up high into the rear bedsides and blew NHOU as far up into the bedsides as I could reach while I had the truck up on my 2 post lift.