Real World Undercoating Test: Fluid Film, NH Oil, Krown and More...

We use LPS 3 on commercial aircraft on hardware and on internal structure, where any corrosion is a big deal. It seems to work quite well in that application. Since it doesn’t stay liquid and continue to creep like the oily products I would only spray it over light surface rust. Even though it sets up firm it applies thin so it will get into small crevices, which is a plus. I’m putting it on a freshly repainted project truck frame to add another layer of protection that I know won’t come off easily.

Thank YOU. CRC it is.

I just had to scrap a beautiful 01 Taurus wagon with only 118k miles, that was treated with Krown yearly. Front suspension subframe completely rusted out, failed inspection and would have cost more to repair than it was worth. Took a $3500 loss on the car.
That was my first experience with Krown, and it will be my last. Garbage product.

Would like to see a new test starting with lightly rusty metal, that's probably when most people start undercoating. Also please add regular used motor oil, bar and chain oil and used cooking oil, those are most popular around here!

I want to see all of these mixed together. It would either make a dangerous gas cloud or the most impervious coating known to man.

CRC and fluid film seem like the clear winners, thanks for the upload. May all your cars be rust free 😃

Would you recommend CRC before doing a Fluid Film or Woolwax?

Project farm also had CRC as the winner.

The dealer or going to a shop with quality up to date coating is far better than it use to be,had a brand new sonata 2009 undercoated,over 200,000 mi,no exhaust work or fuel line,brake line work done and it still looks good underneath!!

I have a quart of military surplus cosmoline. I wonder if there would be any benefit to mixing it into a gallon of fluid film.

Paying for undercoating, I just don't fix the oil leaks on my truck, the truck does it's own anti corrosion! And I don't have to change my oil I just keep adding! I'm ahead of all ya'll

I got a question, if my stock oem rubber coating looks fine on my Toyota can I just leave it on and spray over it again with new rubber coating? Like to make it pop more and make it clean again? I don’t want to remove it all. Considering it’s actually not even chipping off or have any rust anywhere!

Would you use the 342 over rust
Thanks, from Cleveland

I sprayed cosmoline on my truck frame over 2 years ago. It’s still there and not showing any signs of coming off any time soon. I think it’s the best product

Thanks for the video. Unfortunate you didn't use the metal prep for the POR 15 though. Since it wasn't used I do wonder how it may have worked out if it was. If a product has steps they should all be done. Krown may be better on the inside and out of direct elements. It may get into places that are hard to reach too. On the outside perhaps it needs more frequent applications.

I'm an Amsoil Dealer, have been for 23 years. I do not understand where you bought that HD MP and paid $25 because you got raped, this video is 4 years old I'm just now watching it in 2023 and 4 years after this video it's only $15 retail, preferred customer price or wholesale is $11 you said you paid $25 for this and that was 4 years ago you got burnt up.

Great video! Thanks! What will ups you recommend for an already rusted surface? Something that can stop the rust and maybe convert the rust.

FYI - For future reference, it is illegal to attach anything to an electric pole.

Fluid film seems to be a yearly application around fall or spring

Do you think you could use the CRC or even the rp-342 to get a more solid waxy type coating, then go over top of it after it dries with fluid film every year? or would the 2 products cause problems with each other? Personally i like wool wax over fluid film because its thicker, so ive been contemplating putting a good 2 coats of rp-342 on, then wool waxing over top of that every year.

Thank you for these videos though, i could never afford to try all these products at once like this. 👍

Thank you. 👍

POR15 is UV sensitive. Leaving it out on the pole where the sun can get to it is almost certainly why it failed. It either has to be applied where the sun don't shine (ie under a car) or it has to be top coated. They are extremely explicit about this.

CRC corrosion inhibitor is for me. Your the man sharing such an in-depth review. I wonder if anything same as CRC is available here in Scotland ? Thankyou for sharing

Well done

Awesome job bro!

Kind of bs test. Funny that you use fluid film

Great analysis. Simple but thorough. What would you recommend for the engine bay? WD40?

Krown is going to work on dirty car undercarriages. Too thin to work on bare metal.

Have you tried Rust Bullet

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I wish I found this vid before last week! See below. NH Oil application sucks! Not for Offroad Jeeps. All that Vaseline goop has to be wiped off for any Jeep repair guru to perform any work on your rig. I wasted $300. Which could have been better used at a strip club and Chick-fil-A

Rubberized and plastic type undercoatings are the worst . they always trap moisture and destroy connectors shops will refuse to work on your car after ziebart, oil film is the best method or factory wax coating , they allow the surfaces to dry and not trap moisture

Cosmoline was once used to protect cars coming over from Japan. It was removed with a mixture of hot water, kerosene and soap. Very informative video!👍

Nice! Exactly the info I was looking for! Thanks for putting in all the time to make this video and save the rest of us from all that testing!!!

Krown has been sodomizing me for years now.

Cheers for this awesome video! I'm shopping for a used van, and this is my go-to resource for rust-prevention products.

Didnt see Rust Check.. guess it is a Canadian Thing

The POR 15 shouldn't go on bare smooth metal, it should go on a rougher already rusted surface, (wire brushed to remove any loose rust) otherwise it won't adhere strongly and this is likely why it came off. I think the product is designed to stop further rusting on already rusted surfaces.

great job, thanks!

Why the HECK didn’t you test perhaps the best product to use!?:
RUSTOLEUM SPRAY PAINT!

Great channel, really like your videos! Just found your channel looking for a JB Weld exhaust repair, and quickly found you have a lot of very useful videos, and very competent advice.

Specifically I’ve recently been looking at undercoating videos in a casual and ongoing search for the way to best protect vehicles in Ohio winters, without seeing your videos…the “algorithm” fails yet again! Anyway, after watching them I found your undercoating videos to be the best, exactly what I been searching for!…THANK YOU!

Maybe this is a dumb question, but I don't know the answer so...when you apply these - what gets sprayed and what does not? I'm looking at either the fluid film or one of the cosmoline-based products.

Great video mate! You obviously spent a lot of time doing this. Here in Australia lanolin oils are quite common, are any of yours lanolin based?

You're doing as good as Project Farm .... love his videos. Would love to see you do this test again , maybe use smaller pieces of metal... and attach it to the bottom of your truck for all of this winter, come back again in April and report if results are similar to what you have found here.

Great job. As for POR-15, it does NOT have UV stabilizer as part of it's chemical composition. POR-15 application instructions mention that fact. It's best when used as primer and then painted over with paint that has UV stabilizer in it (as do most paints made for use outdoors).

Excellent test. I got a new car that plan to keep for a long time and saved me a lot of research on undercoating options.

Columbus Ohio- I bough my 2016 Tacoma new in November of 2015. I sprayed Amsoil MP HD metal protector on all welds, suspension parts and spare tire. I did this for the first two years and nothing since. I have no rust at 74,000 miles and I drive the truck daily year round.

You really don't have to put 2 coats of the CRC. The directions say if needed. For the most part if you are doing this yearly then one coat is fine. 2 coats would be if you were going to do it again in like 3 to 4 years.