The exposed surface of your silencer, under the car, brushes against bad roads, stones and is splashed with muddy water causing the silencer to rust and leak. Silencer Coating Treatment provides a protective coating. For silencers of all types of vehicles from corrosion and rust. Get this Silencer Coating. Silencer Coating Treatment provides a protective coating. 3M Silencer Coating SL 250 is a protective coating for Silencers of all types of vehicles. It gives Protection from corrosion and rust. It also provides protection for all clean metal surfaces. It forms protective coating without flaking.