I always think it's best to maintain the original paint.
Though when there is more bare metal, rust, primer
left exposed, can't tell what the original color is, after
time with a buffing wheel and polishing compound
and there is no improvement, what you have is a
judgement call to make.
Basically if after a wash, polishing compound, wax,
and the truck looks presentable I would leave the
original paint.
Presentable does not mean like new.
Presentable is dings, scratches, some rust spots,
though most of the paint is there and can be buffed
back close to the original color. So the truck still shines
up and looks good in spite of it's age.
Jeffrey
