Rams with rust

Most of you guys live in "The Rust Belt". Areas that receive snow and ice,and where salt is used on roadways.

When I lived in New Jersey, I would undercoat every new car, truck, van I purchased. Without fail. I usually when to an after market facility to have it done, rather than the dealer. The after marketers would undercoat the entire under-surface of the car/truck..
Body pan, frame rails, fender wells, even above the rear axle, and drive shaft. They would also do the firewall if requested.

If you purchased the good stuff, it was like having the bottom of your vehicle coated with "Line-X" material. lol. Most after market suppliers offered a 10 year/100,000 mile warranty. Of all the vehicles I had undercoated, back then, I only has one that showed any hint of rust. Ever. It was a 1976 Dodge B200 van. I bought it new, and had it undercoated the same week. The rust appeared in the rear quarters, behind the back tires, and was at the level of the sheet metal where the floor welded to the outside skin of the van. I noted it in my maintenance log for the van. It was in November of 1986, some 10 years 4 months after the undercoat date, and at 187,022 miles.

In other words, the the undercoating out lasted both it's time and mileage warrantys.