Using an oil based paint will guarantee a faded look. Rustoleum is a good name but a questionable product. I recommend asking your local independent paint dealer what product he would recommend.

Jumpilotmdm, thank you for your advice. I wasn't aware that Rustoleum paint isn't that good of a product. Do you mean that oil based paint fades faster than water based?

Most do, yes. You can drive by and inspect any house and see where the oil finish coats are by the amount of fade, usually as a dark color, like shutters?
See if they make anything in acrylic that will give you a similar look. Acrylic doesn't fade near as bad but it absolutely must have a primer and anything with rust should be wire brushed and hit with rusty metal [red oxide] primer in addition to the whole-frame primer, which can be almost anything.

"whole-frame primer"

What's that?

If you use an acrylic you will need to prime everything, but you might not want to prime everything with red oxide as it is not usually a large surface primer, unless you're doing a metal roof or rusty front door. The whole thing could be primed with znisser cover stain or similar white, oil primer.
Sorry I wasn't more clear about that.