How much is too much frame/undercarriage rust?
 

I'm looking at a 2003 H2 Adventure w/under 70k miles and despite the normal wear she looks in pretty good shape. She spent her whole life in states that experience 4 seasons (I live in central NC and only get about 1-2 days a year of snow) and she does have rust on the frame and arms for the front tires (I don't know what they are really called but i'm sure you know what i'm talking about). None of it is like corn flakes or is loose or soft feeling. What I'd like to know is what I need to look for so I don't get stuck with a cancer ridden frame and what would be normal for a 15+ year old Hummer.

Really need pics

I fully understand, but unfortunately I don't have any. I tried the forum search function but didn't find anything helpful. I know that no one can accurately diagnose, I'm hoping for some general guidelines or at least what to look out for.

If it's just a light surface rust then its likely nothing to worry about. If you find, as you describe quite well, corn flakes, or peices obviously flaking off, holes, or anything like that than you have a problem. Also be sure to look at the brake lines as those also tend to rust on vehicles from rust prone areas. Just light surface rust, you can spray one of many treatments on that and just leave it be, or follow up with a quality coating. In NC as long as you are not along the coast you reasonably will not have much to worry about. Same for me in central SC.

MixMan, I really appreciate the advice ab's will give it a better look over when I see it again on Tuesday and hopefully she'll be coming home with me. I saw in one of your posts that you were going to use Chassis Saver on one of your frames, how did that work out? I'm in the sandhills right off 95 and have to deal with mud & water more than anything, same when I go down to Estill & Jasper County to go hog hunting. This should be the perfect vehicle to bounce around the plantations with and not worry about getting stuck...done that more than a few times in my F-150.

I actually have not yet had the time to apply it yet.... I'm going to use it on my GMC truck that I'm partway through a major project on. I'm actually hoping to get to that in the next month or so. I'm going to pull the step bars off as well as all 4 wheel house linings and the skid plates off to make access easier. I already have the entire clutch fan and shroud off so that will help with access in the front some too.

It was a "rubberized coating" (Reference GM12378398) as they call, it, but it really had consistency of tar when it was new. It naturally just wore off, and probably not the best decision GM made on those frames. It wore off significantly no matter what State the truck was in. It's only the northern trucks that the rust began to show through. I'm still looking for someone here in Texas to restore my frame but until then, I'm not worried about.

So to summarize, as long as no rust is large, flaky & falling off, soft spots or holes I really shouldn't be all that worried. I don't plan on any rock crawling, or much off roading anyway so I won't be stressing the frame. This will be 99% of the time just rolling on the pavement.

In my opinion yes. Should be fine. I've even taken my GMC truck to Hatteras and driven it on the beaches literally splashing in the ocean. In that scenario I just made sure to very thoroughly rinse the undercarriage off with freshwater once I'm back. The whole thing is light orange but its literally just a super thin surface skim of rust. You can basically just wipe it off.

that is extremely light for sure, this one would require a wire brush to get to bare metal.