Magnesium Chloride is really aggressive material, corroding commercial trucks significantly faster than other ice melting materials. The industry has a big problem with it and the states know it, but still use it because it is best under really cold temperatures.

What you may be seeing is the "chrome" corroding. It is really not chrome, but aluminum that is placed on the plastic grille and other plastic parts. Typically, there is a coating on the aluminum. When aluminum corrodes to aluminum oxide, it turn clear, because aluminum oxide is clear. The same thing happens to the insides of sealed beam headlamps when they get a stone hit. After a short while, the shiny aluminization apparentily disapears and you can see right through the headlamp. Again, that is because aluminum oxide is clear. It is still there on the headlamp reflector, its just not shiny.