I can't say I've ever tried Pam and I'm none too sure that I'd use it. I tend to use Starrett M1, it's a light protectant that comes off in a solvent wash but most any light oil would do for short term use. I wouldn't use something that needs hard work to clean or *anything* with a silicone oil as that stuff just can't be cleaned. Maybe mixing a light oil in the solvent compatible with the paint and spray/brush that on, that way the solvent will be sure to remove it.
Before painting I solvent wash to take the oil/protectant off. After I clean with a solvent I usually use a phosphoric acid and hot water wash (I've used a DuPont paint prep made for auto painting for this) as it etches a little bit and converts any existing rust into iron phosphate. It makes for a great base for a primer. When I'm really serious about the paint I prime with a red oxide primer then use a high build primer to sand before final painting, something I expect to paint again usually gets a couple of coats of paint direct to the metal (unless it's galvanized when I first use an acrylic primer made by Rustoleum for that use).
