Like tom said, if it's rusting from the 'inside out', you'd only be putting a band-aid over the cancer.....it will still continue to rot underneath the POR 15

 

So if it's rusting from the inseide out what is spraying oil in your doors going to achieve? And, again, how do you get the into the pinch seam? Great, spray some in there and it will PREVENT the intrusion, maybe.

So when rust is present and I have the choice between stripping, sanding, priming with POR and painting vs. spraying oil and hoping it gets behind the paint where the rust already is, I'm going with the former.

You are spraying oil-based whatever on PAINT, not bare metal. Why stop at the doors, start lubing the whole damn vehicle down. Might as well start hitting the frame with it too.

 

u gotta remember i started out here just trying to help the best way i knew. my dad put rags soaked with used oil in fenders of his old junk he drove and they didnt rust. in desperation i used what i had,the bg heavy bodied penetrating fluid that claims to soak in and stop corrosion. read about it too.
that got us here,,,now someone carry on. i am looking like yall! and i already squirted mine so for better or worse i did something beside washing and waxing and hoping.

 

I understand you are trying to share some preventative maintenance tips drtom and I am sure those without rust are appreciative.

I quoted the above because while this is correct, it doesn't really address the corrective actions that need to be discussed and, imo, actually may discourage someone reading this from taking corrective action.

The discussion of what to do about rust that is present was completely side-tracked is favor basic rust principles most people are aware of.

Halo - Maybe you can recommend another product similar to POR that is better. As far as I know it's one of the better products out there for this type of application. I have used it with what I feel has been good results. Does it cure rust? No, but it's a hell of a lot better than doing nothing. What do you suggest?

After looking further at other similar body areas I think there are at least 2 factors creating this sitution in this area. As I already mentioned I suspect there was a production issue and maybe that area was not covered as well etc.

Another contribuing factor is the way that area gets pelted with water by the rear wheel. There is some molding and a seal there but I think that whenever it's wet out, the constant spray of the rear wheel gets that area wet. It tends to stay wetter a little longer as well. It also adds condensation as soon as there is any seperation of the paint from the metal. The salt/brine solution those of us in the north have only compound it I'm sure. I think if you strategically placed a piece of rubber in that area you could dramatically reduce the amount of water the rear wheel throws on it. Maybe not.

For those of us that have it, yes it's there and unless you gut the rust out it will simply be a battle of making it as slow and contained as possible.

 

Widespread...I can understand your frustration, and even anger. So far I've been lucky being rust free, but I know I'd be damned pissed to see my Hummer starting to get it. You posted looking for a cure, and all you got were preventatives. I've used something called 'Duro Extend' Rust Treatment made by Loctite. I googled it and came across this: About RUST DESTROYER This stuff sounds good, and IS spray-able, which is what you'll need to get into the drain holes with (unless you want to pull the door panel off, which I'm sure you don't). Whatever you use, if it works be sure and share because it's inevitable we'll all be going through this at some point. Good luck!

 

we talked about duro extend last year on another topic

 

The rust destroyer looks good. The only issue is I don't have a paint spray gun and they aren't cheap (at least the ones I've seen - the guns aren't too pricey but I don't have a compressor). Any idea for how to spray that stuff in there w/out spending a fortune. I'm not opposed to buying a paint sprayer if I can find one that is reasonable (ie. under $100 or so).

 

I've got a couple of these that I use for paint, bug spray, or whatever. They work great. The thing is, you'll need to recharge it from a compressor. You can pick up a cheap ($15 - $25 ) compressor from Walmart.
Amazon.com: AES Industries "Go Green" Aluminum Reusable Spray Can: Automotive

 

i used it yrs ago in spray and brush on. the spray didnt do well in side by side tests on antenna towers. the brush is thick,turns black,and i think should be painted over which i did not do. it still works well and i already did the frame on my 10 last year.
havnt had a look yet.

hard to brush inside!! i dont trust the spray extend.

 

i think it is now "locktite'extend.? spelling?.
i read the instruction on the spray can today. it says,"MAY CAUSE RUST"!! if applied to non rusted metal!!

so as a preventor of future rust,,,not a good idea especially if you spray it into an area you cant see, like a door not rusted,YET!!