I am getting back into Mopars after some time off. I went and looked at a car last night and it had some critters living in the trunk. I am quite sure they have been doing unmentionable things in the lower quarters!

No through rust on the outside and they feel solid. Not much room down there.

Is there a product that I can spray in there from the trunkside to slow things down? I have used POR in the past and I will likely just get a long brush but I thought I would ask.

The car is an A body Duster. I live in the desert and things look ok, but I want to stop anything without removing steel etc. obviously.

Thank you for your help.

Just dump used motor oil in there.

My experience with POR products is that they are a waste of money. I would wash/dry the trunk extensions/inner quarters and then wash them with a rust converter product and wash/dry them again. If you keep the insides dry you shouldn't really have a problem. If you're really worried you could periodically spray the insides with a sticky oil like fluid film.

OK. I literally found live critters in there. I used to own the car years ago and it was about 99% free of rust, it is now 95%! It is actually in the narrow crack between the extension and the quarter on the inside.

Living where I do rust isn't a massive issue. But I would like to do something to stop it. I have the POR on hand and already or soon to be opened for another project.

Eastwood heavy duty anti-rust is like spray on wax in a can. Highly doubt water will get thru it.

You could also look into Waxoyl, try roversnorth.com for it.
Has an excellent reputation in the UK and as you might imagine it is damp there.

I'm sure you know but, make sure you get rid of all the debris that the current residents have left in there.
Personally I like the "Just dump used motor oil in there." idea.

I'd take the used motor oil over POR products any day. In fact, I would take anything over POR products, my results with Por products were pretty discussing.

Whatever you do, like mentioned earlier, be sure you get rid of all the debris left from the current residents before you do anything else. Gene

What are the chances that used oil out of an engine would have moisture in it that was acidic? I think I'd use fresh oil instead of used.

Transmission fluid

This is actually pretty interesting. That's why I am asking. I will definitely be giving the car a serious bath as it really needs it and the critters need to go.

Hadn't thought of the oil thing. Stuff generally does not rust here. And I know that POR has somewhat of a controversial rep, although I don't know why it wouldn't be appropriate.

Why would it be a bad idea to clean it as thoroughly as possible, and then get a long, think brush and apply POR or a very similar product? I'm basically talking about floor level and below on the lower quarter.

I swear by the Krown stuff. Used it when I lived in North Dakota on all my daily drivers and still do. You can get it in a spray can or some cities up north have guys that will apply it. Stays fluid instead of drying and fills all the areas that water (or mouse piss) would normally flow to. IMO it also helps keep existing corrosion from spreading as fast.

Urine = Acid. What better to neutralize acid than good old baking soda. I'd first take the car to the car wash, empty the trunk of it's contents, then stick the wash wand as far down as you can to blast out any junk down in there (you'll likely be surprised at what surfaces!). then dump a box of baking soda down each side liberally add a bit more water to activate it, and let it soak a while (30 minutes or so). Then wash it all back out. Now is the time to spray the metal down with the product of choice, The Krown stuff works good, tranny fluid or motor oil as well but they wouldn't be my first choice. I'm with the "POR15 is garbage" crowd.

Also. when rinsing the inner trunk/wheel well areas, watch that you dont blow water forward and soak your carpeting in the rear floors, you dont want a car with wet carpeting = Rusty floors will soon follow.

POR, if you can get it to actually stick, only serves as a barrier, trapping air, moisture and rust up against your sheet metal.

There is usually a plastic body plug in the lower quarter area. Maybe remove those plugs before you start spraying a pressure washer down there.

When my Dart was at the body shop, they used a wand to spray some sort of petroleum based product into the frame rails as far as they could reach. Said it was to protect the inside of the frame from rust. Maybe look into what that product might be. Good luck.

I have used a product called Fluid Film on my daily driver for a few years now. I have a 300M that I spray the entire underbody with this stuff and it protects it perfectly from the salt and brine.
It would work for your issue, but one drawback. The product has an odd odor that people either like or hate. It is lanolin based, so to me it smells like sheered wool. I hate it for the first week or so after using, then get used to it. On a really hot day, the smell will come back.

If oils ( engine or transmision ) didn't trap dust untill clogs everything would be great idea, but they ending causing a diff problem when saving the other one.

ACF-50
http://learchem.com/products/acf-50.html