My stock muffler is starting to rust and i was wondering if it was okay to spray some wd40 on it to prevent it from rusting any further or would that not work.

 

Your best bet would be to clean it off the best you could and spray it with some high temp black paint. Mine was rusty on the lot with 20 miles on it so the first thing I did was get rid of it.

 

My stock muffler was removed as soon as I got home from the dealer. In the week its been sitting in the garage (first week) it completely rusted to the point where holes were developing.

I would just replace it with a turbo style muffler or something. Imagine the CO poisoning from the pinholes in the muffler!

 

Rusting to the point of pinholes!!!!????

Someone got a bad run of mufflers. My experience has always been that here in the rust belt, mufflers fail on the inside long before the outside is a problem. Unless you crush them or rip them open on a rock.

 

I haven't looked at mine but most mufflers have a small pinhole punched into the end caps to drain condensation. Not sure if that is what you see

 

No. If you look carefully at the welds at the ends, there are tiny hoels starting to form from rust. I live in the king of salt belt. I'm in an area where you can actually get into an accident because of the amount of salt they put on the roads. Its actually more dangerous than snow! Stupid city funding.

 

Especially if short trips are the norm.

Mine is 2 years old. It had only surface rust on it when I decided to paint it with BBQ black. Still looks good.

The JK exhaust is made from 409 Stainless. It will get surface rust on it very quickly, which will inhibit further rusting. It is supposed to last a lot longer than regular steel mufflers.
Obviously, people are seeing varied real-world results.

304 Stainless is the kind that will look new and shiny for many years. It, too, will get surface rust on it. However, it is so thin, it is not visible. If 304 Stainless is scratched, the very thin surface corrosion fills the scratch, protecting the metal from corroding more.

 

I hadn't really paid attention to my JK but I do know that my WJ and all 3 XJs have SS exhaust systems.
Sure, the hangers break off here and there but I have yet to replace a piece of pipe on any of them due to rust failure. Same holds true for the OEM mufflers and cats. The only muffler I had fail due to rust was a Flowmaster and that was a result of rock rash and repeated brackish water baths taken whenever I used the XJ to tow my boat.

 

Replace it! For 4 or 5 hundred dollars you could have a very nice stainless exhaust installed. Plus it would make it sound a little tougher.