alodine.
i dont know if a non comercial place can get it. its a corrosion preventative deal as well. you have to clean to a water break free surface. then you apply the alodine as per directions that im not going to go into as with different brands they varry a bit. then a light coat of non zink chromate primer, you can get it in spray cans or two part, then you LIGHTLY sand the primer and hit it again, then you paint it. now, this is for aircraft methods, so maybe automotive methods are different.
Grant