so i took some time to read this entire thread from start to finish
As my next car is going to be a keeper I'm very much on the fence of doing something.
When I plan to keep my cars i'm very anal about making sure I keep it clean, always spray and wash out the wheel wells. In the winter and after driving on dirty roads (even in the summer) I get on my hands and knees and spray under the car to make sure all the crap gets off.
My 1999 Forester was the car I held onto the longest. It was 10 years old when I got rid of it. It was a used purchase in which I did get the Krown the first year I bought it but didn't keep it up. It had no rust and still looked great when it was traded in.
I can't honestly argue that Krown or any other application will for sure save your car.
I do think however that keeping it clean is most likely the most important aspect of maintenance and ensuring it stays looking new.
I can say that I feel anything the dealer offers is a cash grab. The Forester was traded in for a new RAV 4 which I originally intented to keep. I opted for the dealer spray which cost $500 and came with a "lifetime warranty" The warranty is what sold me. However, what was NOT explained at the time is that the vehicle did require annual inspections. While it was no charge, it was still a PITA. The first two years I got a notice in the mail and what the dealer also didn't warn you about, if you miss one inspection the "lifetime warranty" becomes null and void. In the third year I got no notice and forgot. In the forth year I realized that the dealership was now using another company. When I asked why and what happened to the other company, I was simply told that "they're not around anymore."
Did the application help? I didn't have the car long enough to know. But with the idea I was buying a product for a "lifetime waranty" I know that became null and void pretty quickly.
I'm not sure how often a dealership changes the companies they work with, but I'm thinking at least Krown has been around for a very long time.