That white stuff is basically salt, whether it is calcium chloride or the more popular magnesium chloride. The application of these chemicals on our roads is certainly needed here in Colorado. However, they are extremely corrosive to your vehicle’s paint, metal, and undercarriage. It is important to clean off that residue as soon as possible. Our top automatic wash includes a polymer protectant that acts like a shield against magnesium chloride and UV rays. We suggest that you protect your car with this wash, the Ultimate Plus, at least once a month and more often if weather warrants. This wash also includes the protectant in the undercarriage wash.