Opinions vary
Case colors are lost primarily by abrasion, but some oils and chemicals also degrade CC, especially if acidic or alkaline.
Dr. Oscar Gaddy used Behlen's to protect CC; others recommend thinned TruOil.
It is certainly reasonable to protect the colors and metal with a quality wax such as Johnson's Paste Wax or Renaissance Wax.
As is shown however, over time the lacquer will be scratched.