If this belongs in another section of the site, please feel free to move.

I live in NY, and as many other residents in the NE know, rock salt and cars do not go together. Long story short, my muffler section is done. Got it replaced today. And the mechanic is saying my resonator is starting to show signs of wear. Is there any way to seal it off to prevent future leaks? And is there any other way to keep the undercarriage in tip top shape other than regular washes? Thanks