I use Master Formula Sealer & Metal Gloss to keep it clean once a year- sometimes longer. It works for chrome, aluminum and stainless. I use it on my exhaust as well. It's relatively inexpensive on ebay and it works well. The shine stays pretty bright. I would note that I rarely drive the car, which is likely why I don't have to polish it as often. On the other hand too, the chrome parts on my car rarely need touched if ever. It's all in what you want. IMHO.
