Can't really tell you because the material of the grill is dependent on how or if it can be cleaned. Cast iron grill can be cleaned with a wire brush, the inner basin..is it metal alloy, pot metal...etc. The outer surfaces are they porcelain covered or steel....a paint scraper (plastic or metal can make it easier to get off any deposits in/on the basin.
Is it to the point of rust on the surfaces? Overall I'd say use a wire brush and maybe a steel wool scouring pad on the inner areas, but make sure you clean well after to be assured that no metal wire bristles have been left behind...that can be deadly. Soap and water on the outer surfaces and finish with a cleaner described for your actual surface.
