Rust

coke at least in the past has a small amount of
phosphoric acid in it,
in the 60's we'd use coke on the chrome, then use
aluminum foil and wipe over the area, the aluminum
leaves a coating to resist rust.
Any type of acid will desolve rust. It is just that
vinegar comes in 1 gal bottles and is $2.50
and is environmentally friendly
decades ago I used Tech grade phosphoric acid, when
it was like $10 a gal, now it's $32 a gal
my point about the rags is that you can do larger
pieces at home, fenders, inner fenders hood, trunk lids
The bumpers on my wagon show no rust through the
chrome but the back side does, so It will get a
vinegar bath