I've 1994 Chevy Truck. In the past (not sure about now) GM used a black oily waxy substance on the frame instead of paint. Over time, rather quickly, this stuff came off (undercarriage car washes). Where it didn't come off dirt stuck. I spent years under my truck with assorted wire brushes removing this stuff and applying paint like products. Too much effort...
What I found that works better than all of that is Fluid Film. When you put in on it stays wet but drys a little to a waxy shine. It penetrates and gets under lite rust. Also, It flows well into sheet metal seams (like fender wells and doors) and rubber (like bushings). It has a high flash point. I use it on some engine components like the water pump (not exhaust) which loves to rust.
I buy it in aerosol cans (by the case) and apply it yearly. It collects dust, like the original GM product, but can be washed off with a pressure washer. So far, I just add another coat and don't worry about the dust. I gave up removing the original GM waxy film and just spray this on top.
I have read that in the really old days service stations used to spray used oil on the frames of cars for anti-corrosion. I've notied that where there's oil, there's no rust. Anyways, that van looks like a good candidate for Fluid Film.
Why you have to keep on your GM frame:
http://www.gminsidenews.com/forums/f22/why-does-gm-wax-dip-truck-frames-39112/
http://www.gminsidenews.com/forums/f22/wax-coated-frames-79626/
Review:
I think you can find the original GM product in a spray can if you look around (not my choice). Again, I'm not certain GM is still doing this wax dipping corrosion treatment. After years of fighting rust with paint I'm slightly against paint if it has to be applied on top of the GM treatment. And, I think the GM process is good if they just told us how to take care of it. The van looks like, perhaps, the corrosion treatment washed off.
Thinking about pulling the trigger on this 2012 Chev Express 2500. Van looks really good ONLINE. Has 55K miles. One owner, Ohio. This picture has me alarmed. Is it rust? Are they showing a problem, or proud of how good it looks underneath? Carafax shows very good maintenance records. Thinking of looking at it this weekend though it is an easy 70-80mi drive each way.
I like to tinker and fix things especially if I can do so before they become a problem. I'm the kind of guy that hopes that I'll never have to buy another vehicle - kinda like the old saying about if you always keep a spare handle and head, you'll never have to buy another axe. And I guess it might be a bit foolish, but I just always assume most people are interested in maximum longevity. See, rust is a cancer, and while I understand that not all cars can be Texas cars, I don't mind sharing tips on how to get more out of that rolling investment in hopes that things will never get "terminal." Just my 2¢. Now you have a good one. Cotton
