Jeep uses 409 Stainless Steel for its exhaust including the muffler. It is an inferior grade SS that can rust. T304 is the true marine grade Stainless Steel that some of the highend aftermarket exhaust systems use.

Manufacturers are required to use stainless Steel by law for new vehicles but most use the cheap grade, no surprise!


Mine has rusted and looks awful also. I am not sure if I will replace, or paint.

I think it will spend the 5 bucks on paint!

 

Thanks for the info. That explains why mine is rusting already (2 months old). And it explains how they can get away with saying it is stainless steel.

 

This is what I came up with about 409 stainless. It's not as bad as I thought.



Corrosion Resistance
Grade 409 resists atmospheric and exhaust gas corrosion. A light surface rust will form in most atmospheres; this rust retards further corrosion but makes the surface undesirable for decorative applications. The corrosion resistance is about the same as that of 3CR12 and the 12% chromium martensitic grades such as 410, and inferior to the 17% chromium grade 430.

Heat Resistance
Generally 409 is classified as resistant to scaling in intermittent service up to 815°C and up to 675°C in continuous service, but these temperatures are dependent upon the exact service environment.


Applications
Typical applications include:

· Automotive exhaust systems

· Catalytic converters

· Mufflers

 

It sure doesn't like stainless under there any more! I didn't do the old magnet test but to the eye, it looks like straight old steel pipe and muffler. Quite dissapointing.