I just bought a 1985 300cd in fantastic condition. I've never owned a MB and I am just amazed at the quality and comfort of this vehicle. I want it to last forever! Living in Florida, rust is not a major concern, however I will be moving to northern Indiana soon and I do not want my car to be destroyed by salt on the roads during the winter. Is frequent washing enough to prevent rust or should I go to somewhere like Ziebart?