You have heard Kent harp before on keeping those water drains cleared out and flowing freely. Well here is another example of catching the problem early. Before the rust starts! If you let the rust go unattended you will have holes going into the passenger compartment.
Easy preventative maintenance you should do at least every six months... unless you live in the desert..:-)
W110 W111 W112 Sedan
W111 W112 Coupe