Krylon makes some. I am sure many more do to. There are guys that use oil. There are enamels, acryics, and now some water based,(not sure how that works). Most come in gloss, or matte.
No paint is going to protect it. The clear won't bond with bare metal and it will only wind up rusting underneath it, flaking and looking like hell. It is also a pain in the ass to get it off when you move on to better things. You're better off with a scotch-brite pad and some WD-40...
I would try some PPG omni clear over it after sanding it with 400 grit DA. I don't think you could leave it parked out in the sun everyday because the reflective heat from the metal would bake it off from the metal up. I think if you keep it in a garage when you're not out driving it, it should actually last quite a while.