Both axles and the frame are/were covered in rust when I bought my JK in early 2010. I've since undercoated it. It's starting to come through the undercoating though. What concerns me more is that the underside of my tub is starting to rust where the seams are. If/when I buy a new Jeep the first mod will be to have it completely undercoated(professionally).

Oh yeah, I have the typical hinge bubbling and seat hardware rust too.

 

I bought mine used. When I bought it, the dealer only gave me a 6 month warranty. I figured I was just outta luck.

 

09 here, got some rust showing up on the metal fender and the plastic fender at the angled part.
got little rust here and there on the frame and axels nothing to bad as it see Canadian winter as a DD sleeping in a heated garage !
I did notice the hand brake line support are rusting really fast and will at some point need to be addressed

 

x2 The plastic fenders on my JK have worn through the paint on the metal fenders. I don't have any rust yet, but I'm expecting it. I always contributed it to having the OEM splash guards on there, but maybe that's not the case.

 

Are the newer hinges steel? Perhaps If I'm going thru the trouble of repainting them, I might at well buy a new and better hinge... Thanx for the info about the alum. Against steel.