Green scotchbrite is too abrasive, imo. The most aggressive that I do for enamel is 1000-grit silicon carbide paper, or 000 or 0000-grade steel wool. The steel wool can be wet, if you load it with baking soda (will not rust when dry), or load it with automotive paste wax, or oil. Metallic oxides expand when the form, so going over the surface with something to remove the rust to the level of the surrounding enamel or sheet metal will allow the rust to shine, and nicely polish with paste wax, or oil, and a rag. I remove stains from my teeth with baking soda, a moist coffee filter, or a dulled hardwood toothpick, it is the right amount of abrasive for stain removal.