Good report and thanks for sharing. But many people in the rust belt still believe these treatments are snake oil.
Krown works but is very thin and washes off very easily. Many old timers would drive on some dirt roads after an application to get some dirt stuck to it, which helps with wash off.
In your case the factory wax coating helps Krown stick to it and prevents it from being washed off. And yes, oil spray will help the factory coating last much longer and keeps it from drying out.