Lets talk about rust on the 2nd Gen Avy...
Rear Fenders
If your rear fenders are bubbling,
CHECK OUT THE INSIDE NOW! They are very well likely filling up with debris and trapping moisture. Remove rear tail lights and you can get in there to check it out and clean them. I was able to completely save one side of mine while the other has very minor issues that I've been able to keep at bay for a few years now.
Rear Quarter Panels / Rockers
Get some (ok,
many) Eastwood Internal Frame Coating spray cans and spray the heck out of the rocker areas, especially the rear areas in front of the rear wheel wells. Over time, moisture in the air condenses on the inner walls. Combine that with salt from the environment, freeze thaw cycles, etc and the coating gets destroyed.
Lets take a look at the inside of this area;
Note that there's no debris in here. These areas are clean as a whistle on my truck. This is purely the ambient environment that goes through temperature cycles, condenses and slowly eats away at the inside and once the rust starts, it explodes. The lack of good protection on the metal body of these vehicles is disappointing to say the least.
Lets look to the left now...
Here we see a view from where the wheel well sits right behind the left area. The most rusted spot in the bottom left leads to a drain hole. Again, it's completely clean in there but it's still rusting out. You can spend all day long detailing the heck out of the vehicle and it will still rust out without proper preventive maintenance and protection
from the inside.
Front Fenders
Another area to be concerned with are the front fenders. They are prone to rusting from the back side of the wheel well near the front doors. They're compounded by the fact that they act as main drainage areas. Some stuff can get into them and become trapped but it's constantly hit by water from rain/snow/etc. The front lip of the fenders on the side can also rust out from the inside too over time. Since the surface is relatively flat, junk can get in there and just sit.
Here's the areas prone to rusting out on the front fenders.
The Z71 models have factory fender flares that hide a lot of what's going on. This is partly why I never caught these issues until much later on mine. It just so happens that due to an accident (not at fault) I now have the chance to replace both of my front fenders with news one. That'll completely resolve any rusting going on with those.
Bottom Door Seams
If the bottom of your doors show no signs of bubbling or rusting, take off the plastic trim at the bottom and check under there. Get a can of compressed air, blow out the drainage area along the bottom and then spray it up with something like Boeshield. Believe me, it's much better to stay on top of this stuff now then deal with the rust carnage later. I wish I hadn't had dropped the ball a few years back. I now have my right rear door bottom seam suffering minor rust damage that I've had to spend a considerable amount of time cleaning up and "repairing".
Gas Tank Filler Opening
Ahh, yes, the gas tank filler...
Now here's an annoying,
and stupid!, design decision. If you open up the cover and look at the body seam right there at the bottom of the fuel cap you may find that it's not perfectly sealed. Water can get in between there and trickle down inside the panel. Now, normally that really wouldn't matter. It's such a tiny amount of water, except GM decided to put a line of soft body foam right above that body crease there. So where does the moisture now go? It gets trapped between the foam and the metal. Fantastic!...
not! Best thing to do, even if you have no bubbling below the cover, is to get some sort of tool (it's incredibly hard to really describe here) but, remove the rear light, and you can reach in there with something and rip away the foam so water doesn't get trapped there. The other thing to do is protect the seam with some sort of seam sealer or heck, use silicone grease. Anything to prevent water from going down that seam.
Dang, I may have to write up a whole thread on this stuff... if you want to know more about anything I've mentioned here, let me know.