DIY rustproofing

After my 10 yr old 150 rusted through the doors I thought I would get proactive with my 3 yr old Super Duty. I got under with the garden hose (more flow and better angle than pressure washer) and cleaned dust and sand out of every place that I could find that could hold anything between panels and brackets. Then after drying overnight I sprayed WD-40 to displace any remaining moisture, followed by aerosol chain lube to penetrate and provide protecting film. What do you do to try to preserve your truck?

Do pretty much the same thing to my trucks, I use open gear lube in spray cans from napa. Like you I first clean everything, then spray the gear lube on the frame, brake and fuel lines, gas tank etc. I then spray every thing else with hydraulic fluid, inside doors, fenders tail gate etc. The gear lube will actually dry to the touch after a couple of weeks. Do a search on rustproofing on the cheap I posted, got some negative replies. Dave

I know a guy that used to drill the bottom of doors and everthing, took pannels off and sprayed inside of pannels with used motor oil. and said it kept from rusting. but I always thought that oil would draw moisture. I allways try to keep holes in bottom of doors open & other pannels clean "of mudd & other things".I usualy get at least 10 to 15 years with out rust. But I haven't owned a ford in 30 years, The last one I had was a 69 Bronco put 300,000 miles on that dude was just about as tough as they come no frills just a "plain Jane" didn't even have a radio in when I got it used with 120,000 miles on it,total miles when I got rid of it had 420,000 miles on it. the guy I sold it to drove it another 5 years.

Have you checked into commercial truck bed undercoating? My jeep xj Has it (which are notorious for rust) And it doesnt have a spec of rust on it

Once you have the inner panels clean and dry, use the regular "Inner panel Rustproofing"..

It is thinner and dries to a flexible, waxy coating..
I think this is best..

For rusty spots, "Rust Converter" can arrest rust progression pretty good..just re-apply every several months..
Don't breath the fumes tho..it can really choke you up..!!
As for my old 2nd hand Jeep with open holes..I oil it down pretty good,,!!

Before you do any undercoating, you might want to check your warranties. A lot of new cars have a ten year warranty against rust through, and undercoating the vehicle will void the warranty.

The warrantees I read say " aftermarket undercoating may void warrantee only if it contributed to premature rust out as in the case of plugged up drain holes etc". Also most warrantees are for "rust out" or "perforation" only. that means if it aint a hole through then it's considered "surface rust" and they will tell you it is from lack of proper maintenance (cleaning) and won't cover it. Where I see the biggest problem with most vehicles is the bottom door seams where outer skin is lapped around and over inner door. These aren't seam sealed any more and when you slam a door it does cause these two seperate panels to "move" on aech other and it not only cracks the paint/primer but also cracks loose the galvanizing and then the salt/dust catches in the lip and eats away at newly exposed metal and gets in between the two layers and by the time you see it , it has rusted long enough to bulge the two apart and when you sand blast it a lot of it just dissinegrates. Undercoating from the inside only helps with half the problem. I know it is a little unsightly but you must seal this seam/ledge with silicone or some other flexible sealer the day you buy the vehicle new! This area starts cracking the first time you slam the doors! You just won't see it until it's too late Certain doors will rust on the bottom seam first in the exact area where the door lift robot at the factory grabs on to the bottom seam. This thin metal flexes more than anyone thinks and just because you can't see it doesn't mean the coatings havn't cracked. Have you noticed the driver's door is usually the worst? Has nothing to do with more salt in the center of the road either. Salt gets everywhere. As long as it finds no bare metal it hurts nothing. Have been repairing and observing these problems for over 35 yrs and there's a pattern to it. Never thought we would still have the problem with 2 sided galvanizing but if the coating flakes off and exposes bare steel because of expansion/contraction and/or viberation then you have problens. No matter how new your car/truck is , lift up that rubber waether seal along the bottom inside of you doors and clean and check it thoroughly. Even if you have to use a magnifying glass. If it is 2 yrs old you may only see stress cracks but 4+ yrs you are liable to allready see "spider webbing" under the paint. That's just the prelude. Get it taken care of now. I am from the salt/rust belt of the country , if you are from a state that doesn't use salt , EVEN in the summer for dust control , then you may be safe. Do you ever drive to a state that ever uses it? Only takes one trip through and you've got it. If you live close to an ocean you have it everywhere. Bottom line is , you can seal up everything but if you use it eventually it will crack somewhere . View it as maintenance and watch and check once in a while. Once you see the "big brown" it's too late!

B, That lap over is exactly where my '99 150 had its problem. So my plan with the 350 is to keep after the edge of that seam by keeping it clean of dirt and dust and keep it coated with penetrating oil. My experience with rust/salt is that it will penetrate further than I can get at by cleaning, priming and painting but by keeping oil on it I will keep the rust at bay. I wish I had talked to you twenty years ago!

Most all newer cars and trucks use foam inside the panels. This is the first place they go as it holds the moisture.
I remember a Ford commercial a few years ago about their quiet cab ? all they did was fill it with foam. These will rot out fast !
I have kept ATF sprayed in and on my 1996 Dodge and have used some other undercoating stuff on the brake lines and underneath too. This has really helped,but it is still rusting in spots. Ohio uses lots of salt and calcium cloride on the roads.

Regarding the used oil method suggested above, I've read a couple of times over the years that used motor oil has all sorts of nasties in it as a by product of the combustion process -- some of it carcinogenic. Most of us get enough exposure to it just changing it out of our machines. If true, I wouldn't want to drive around in a vehicle soaked in it.