I had a 94 Dakota, that I bought in 96 with 10,000 miles.
Every time I changed the oil, I popped the door panels loose, and poured oil in the bottom of the doors, took the tail-lights out and sprayed as much as I could back thru the bed. If there was any oil left, I took the bed liner out and put the rest onto of the bed.
It was driven year round, when I sold it to my neighbor, it had then about 120,000 miles and was rust-free.
His son drove it for several more years, then I seen it running around town for many more years, it was still showing no sign of rust.
I should have kept that truck 6 cyl magnum, 5-speed, 3.55 gear sure-grip, standard cab, shortbox.
The only thing I did beside maintence was one water pump, it was just weeping slightly, and a fuel pump, that would not pump good under 1/4 tank of fuel. Never left me walking.