Yeah, that's my impression from reading threads on rust protection on snow plowing forums. Its going to probably have to wait until spring or the next dry warm spell to spray the inside of the frame.

 

I swear by rust bullet. I bought the 6-pack of 4-silver 2-black in quarts for my northeast US salted road and outside living 89 blazer that got a 80% floor replacement, rockers, and more. I covered everything rusted or bare metal with the silver stuff first and it basically froze up everything and the thin rust spots started feeling a lot firmer. 2 coats of the silver and 1 coat of the black shell coat. I couldn't recommend it any higher. That's just personal experience, and I'm no plow truck driver, but it worked for me!

 

I took a bit of a novel approach, since i work on guns a bunch, I pulled mine up on some ramps, crawled underneath, and sprayed everything down with Breakfree CLP. I even called the company and asked, if i get this stuff on gaskets, rubber, hoses, etc., will it do damage? they said no, and spraying the under side of the car would be a great application. So i did it , but first I sprayed down everything with foaming engine greasy spray cleaner. let it sit for about 15 minutes, then did the Breakfree. I am very happy with the results.
wear a mask, and eye protection.

 

depending on your usage, get 4 to 6 cans of each.

 

I've heard of spraying with used gear oil rather than engine oil. Makes sense to me with geawr oil being sticky and everything. The thinning with kerosene trick sounds nice.

 

I use a compressor and spray can like slacker uses, and I tend to use 80w90 gear oil as it will stick to anything. It reeks but man does it ever hold up against, wind, rain and salt. I usually do it once or twice a year. and every couple years pay someone to do the doors etc. I usually spray everywhere I can because I am standing underneath a hoist.

 

Corrosion x is a great solution to undercarriage and inner body parts corrosion. It's widely used on inner frames of air craft to inhibit corrosion, and, yes aluminum does corrode.
http://www.corrosionx.com/

In the past I've tried all manner of frame rust inhibitors and coatings and none of them really worked very well, none worked as well as Corrosion X Heavy Duty or Max WAX. They sell spray wands for applications on internal frame parts.

Products like POR 15 and undercoating paints must be applied to metal that is rust free and primed with rust inhibitors or else the corrosion will continue to grow underneath the paint coatings.

Not all oils will work well as rust inhibitors. Some oils work better than others, ask any gun smith or salt water fisherman. Motor and gear oil is designed primarily for lubrication and not rust protection. Unless motor or gear oil is pretty much continually washed over the metal over a period of time the motor oil will tend to collect, hold and transfer moisture to the metal surface thereby promoting the breakdown of the metal surface, you'll notice it will start flaking off layers of oxidized (rusted) metal. You can prove this to yourself by coating some bare steel nails with motor oil and and some others with a good quality rust inhibitive oil and then spray them both with a salt water solution every day. You'll notice the motor oil coated nails will begin to rust way before the nails with the rust inhibitive oil.
See http://www.thegunzone.com/rust.html

Try Corrosion X, you'll be amazed.....


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[QUOTE=slacker;50891891]I use a "shutz gun" and a small paint brush to do my frame ..
2 wands .. first is a rotating 360* "V" notch . Second is a 90* rotating .

Did you POR 15 the INSIDE?

 

[QUOTE=jetpilot;51133315]YEP .. have a look at the pics ... you can see threw the "holes" the inside is done ..

 

Just in case anyone is actually tempted to use expanding foam inside the frame - DON'T. That stuff is porous and holds moisture like crazy. It won't do anything but turn your frame into a crack-filled rustbox.

 

And i bet the expanding foam will catch fire if you need to weld the frame, i wonder how cosmoline in a more liquid form would work. I used to see bricks of that for sale at gun shows