Two things that keep the shine down--oxidation and absence of a gloss (flat) surface. I like to use diluted Jasco prepaint conditioner. I spray it on with a garden sprayer and agitate with a soft brush, then rinse. That removes the oxidation in the paint. I'm currently using Parfe liquid wax but any wax is good.
On automotive finishes I'll use a clay bar and Extra fine rubbing compound. That kind of work is reserved for cars that I own where I can spend the time for the results. On an RV, it is overkill, IMO.
