Undercoating Products

[MikeYQM]

For anyone that undercoats their vehicle I figured I’d share my research and results as to what product is most effective at preventing rust.

The Canadian Forces did a study on many OTC solutions and found the following effectiveness of corrosion prevention:

Rust Check 40% inhibition
Krown 60% inhibition
ACF-50 70% inhibition
Corrosion Free (Canadian Tire) 90%

I’ve also read that Fluid Film performs very well but for no direct comparison; I created my own. I coated 1/3 of a piece of metal in Corrosion Free and 1/3 in Fluid Film and left 1/3 bare as a control.

These were left to sit for 24 hours. Subsequently, every 24 hours the sample was submerged in a salt water solution then left exposed to air.

In the first photo, the top image was immediately after application and the bottom photo was after 10 days of daily salt water immersion.

As you can see from the photos, not only did the Fluid Film remain in place through the salt water better than Corrosion Free, but after only a few days there is considerably less corrosion.

In the second photo, I cleaned then sprayed the whole sample with FluidFilm to test how effective it was at stopping corrosion that had already begun. In the top image, was day 1 and the second day 7 after daily salt water immersions. There appears to be little to no spread of corrosion after Fluid Film treatment on the area previously covered by Corrosion Free 3000.

Where these products are mostly the same cost, Fluid Film appears to be a better solution, but that’s just my opinion. These tests are by no means conclusive or scientifically sound. They were designed to help me decide between 2 very highly rated products.

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[4runr4eva]

Good work. I may pick some up before the weather gets too cold to make sure my baby makes it through many New England Winters. :hatsoff:

 

[arthurm]

My experience:

1. I've tried Corrosion-X for a few years on Land Rovers and the 4Runner. An annual spray underneath lasts the year and Boston winters. It appears to work well. It's an industrial grade product used onlots of things.

2. This year I sprayed the inside of the bodywork on the 4Runner with Valugard VG-101, a wax product. This is to prevent rust inside the panels, so not undercoating per se. This product is the official product for several auto manufacturers to handle warranty issues. Valugard was also the official US importer of Waxoyl, until they separated because of Waxoyl's unethical practices. They then developed their own products.

3. There is also Valugard VG-104, a more traditional undercoating product. Haven't tried this but expect to.

 

[Breadman03]

I've been considering Fluid Film for my '11. I've got some light for the area rusting and want to address it as I'd like this to last long enough that I can buy a replacement with cash in about a decade.

 

[fourwd1]

Interesting.
Moving from 5th Gen to General Discussion section where others can benefit.

 

[MikeYQM]

I've been considering Fluid Film for my '11. I've got some light for the area rusting and want to address it as I'd like this to last long enough that I can buy a replacement with cash in about a decade.

From what I can tell, FF does a good job stopping existing rust from spreading. It doesn’t cure it or encapsulates it, but does seem to arrest it.


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[zcruiser]

Reminds me, I need to reapply FF before winter.

 

[Coal-Cracker]

Looks like I'll have to pick up some Fluidfilm.
My last few vehicles, I'd spray WD40 on the undercarriage and it did an *okay* job as a rust preventative through Northeast winters.
Im always looking for product improvement.

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[Mr.SDP]

What's best if chassi had rust already?

 

[T4R2014]

What's best if chassi had rust already?

Grind it until clean. No guarantee that it will still be a safe metal thickness (if any metal) after that. What isn't will require new steel welded. Then a rust converter to convert whatever small speck of rust not visible. Then primer(preferably epoxy). Then paint. After this you cover it in oil. Any oil. Fluid Film, WD40, used motor oil, bar and chain oil, and even roofing tar. Take a drive on a dirt road to get a light layer of dust on that oil. After this, you will be golden for many years. If you're lazy or not wanting to waste time(remember that labor and supplies could often cost as must as some older 4Runners, making it cheaper to buy a west coast truck) grinding away the rust, just spray the oil over the rust and it will be stopped in its tracks.

No liberal nanny rust belt state will ever generate enough tax revenue to buy enough road salt to rust out an oil undercoated truck. Just be mindful of rubber bushings as the oil could have negative affects. Maybe a shot of your favorite rubber dressing to protect them? Just my findings after reviewing vehicle preservation options from parts of the world where buying new vehicles is often not an option due to cost.

 

[Mr.SDP]

Thank you for the advise.

 

[Mr. Goodkat]

I started using Fluid Film a few years ago when I received my 2014 FJ Cruiser and I did a similar test. I put a few gun oils and FF on a bare piece of sheet metal that I left outside for a few months. The FF was applied two ways, it was wiped on in a thin layer and sprayed on in a thicker coating. FF did best in both application methods over those months even though salt was not involved. The metal under the FF was rust free.

Sadly I don't have the FJ anymore (the high payment got old) but I bought the FF spray gun and wand attachment which really makes the application much easier and quicker. I live in Upper Michigan and my FJ had an undercoating but I still sprayed FF over that.

I just acquired a 2000 4Runner with 203k miles on it but it spent most of its life in Colorado so it's pretty rust free. I've been told there is a mechanics' shop around me that can apply undercoating on older vehicles but I haven't looked into it yet. Either way, my 4Runner will be getting a heavy coat of FF before the snow flies.

I recommend FF. It's also good for other things such a coating metal working tools, a dressing for seals, I lubed door knobs before assembly, lubed door pivot points, and even tried it as gun lube but that's, really messy. It's good for protecting firearms from rust though.

I should add that I'm also thinking of wiping a thin layer of FF over my lower doorjamb areas and along the bottom edge or lip of the doors.

 

[arthurm]

I thought FF only works when there's no rust in the first place. Well, most of us already have some rust. So, I'd try:

1. Corroseal - must apply it thoroughly and correctly (i.e no contaminants) or it's tough to remove and reapply.

2. EvapoRust - must apply as a stream for a few hours but gets rid of all rust. You can dip parts in a bath or setup a parts cleaner small tub, with pump and a hose over the part and let it run overnight. Like an axle - put a hose over the rusty part of the axle and let it be for a few hours. Or a brake caliper, let the hose drip over it and recirculate for a few hours. Yes, I know it's difficult for treating undercarriage parts but it's doable. And it gets rid of all rust, not just convert it. Then coat the part with FF or something else.

3. Phosphoric acid - from Home Depot. Spray on and then wash off.


Look, there is no one best treatment. Whatever works for you is best.

 

[WeakSauz]

I haven't had a chance to read this thread word for word yet, but let me proceed with a word of caution on rubberized undercoating.

It's great stuff IF applied correctly.

I have a good friend with a T100 that just simply wiped down underneath the truck, did minor sanding, and then sprayed on rubberized undercoating.

Fast forward 2 years, and this truck is a total loss. The Undercoating began lifting from the frame, and moisture was allowed to get underneath the coating in the lifted spots. Ate the frame out (underneath the coating!).

There is a right and a wrong way to apply it. He lazily did it wrong.

You must first remove all rust, prep the surface, use a rust inhibiting paint, and then prep again before applying any undercoating.

At least.. I guess that's right. I personally am not going to use any coating products other than WD40, or Fluid Film after what happened to him. I'm more of a remove the rust and rattle can-it kind of guy now.

 

[j4run]

+ 1 for FF and the kit (spray gun, extension hoses, etc.). Been working great for me. I can't imagine trying to do inside the frame, and all the nooks and crannies with rattle cans. The spray gun and extensions are great, and if you have a compressor, it'll be less expensive after a few years. If you don't have a compressor, get one!!

 

[PharRunner]

Those rust converters can actually make your car start rusting much faster. Id stick to some >93% zinc spray then apply a layer of corrosion x or fluid film