I am cleaning my rims and my fiance's rims this weekend and i need some help for hers. She has a taurus (at least its a ford) and her rims look like they have a salt build up on them but its not salt and it won't come off with water. I was thinking about using Mothers mag and alum polish on it to see if that will take it off. i really have no clue what it is. I am also using the same stuff on my alluminum alloys. Does this sound okay?