Opinions on Undercoating

[Sharecropper]

OK I know this may be a volatile subject, so before I get flamed please consider my specific situation -

My M1028 sat on a National Guard Base in Arizona for 25 years before I got it. It had, and still has, Zero rust on the underside. In fact, the underside of the cab looks almost new.

I am preparing to install the auxiliary tank and replace the OEM tank, and want to apply something to the cab bottom before lifting the new tanks up in place. I want to apply a product to achieve three goals - 1)- to coat the underside to prevent any rust from ever getting started, 2)- to reduce road noise, and 3)- to improve insulation value because I am planning to add A/C in the cab. I understand this issue has been debated on this forum several times before, and in fact I believe it may have even made it to the floor of the U.S. Senate with no resolution. Maybe this time we all can come together and agree on a product to use.

I have looked at Lizard Skin, however I do not see how such a thin coating can provide much insulation. I considered LineX, but I need a product which I can add a little here and a little there over time, so I need a product off the shelf in rattle cans. If a GM dealer were to undercoat a new Chevy truck, what would they use? Ideally, I want a product that can be built-up to a thicker coating than just a film. Once the new fuel tanks go back in, they will not come back out, so whatever I am going to use needs to be applied now.

I would appreciate responses from guys who have had experiences with undercoating, instead of opinions or left-field suggestions from non-experienced folk. Hail I can Google as well as anybody. Just remember this - I am going to use something, so don't try to talk me out of it.

Anybody had any experience with undercoating?

 

[MarcusOReallyus]

Undercoating can sometimes seal in moisture and hide rust. That's why I prefer Fluid Film for rust prevention.

Sound deadening can be done inside the cab.

 

[LT67]

Undercoating can sometimes seal in moisture and hide rust. That's why I prefer Fluid Film for rust prevention.

Sound deadening can be done inside the cab.

^^what he said

 

[glcaines]

GM Fluid 12378398 Rubberized Aerosol Undercoating. I've used this product and found it very good. You can find it on Amazon and other places.

 

[Sharecropper]

Undercoating can sometimes seal in moisture and hide rust. That's why I prefer Fluid Film for rust prevention.

Sound deadening can be done inside the cab.

Thanks Marcus but there is no moisture or rust on my truck. It hasn't seen rain since 2010. The cab bottom is in almost new condition. I am looking for a rubberized coating such as is suggested by a later post.

 

[Sharecropper]

GM Fluid 12378398 Rubberized Aerosol Undercoating. I've used this product and found it very good. You can find it on Amazon and other places.
View attachment 832799

Thanks. I believe this is what I am looking for.

 

[Sharecropper]

Undercoating can sometimes seal in moisture and hide rust. That's why I prefer Fluid Film for rust prevention.

Sound deadening can be done inside the cab.

Marcus I looked up that Fluid Film. Wow that is some wild stuff. I believe if I was going to be getting my truck wet and nasty every weekend like some half-cocked teenager, I would probably buy and use that product. I will have to agree with you, Fluid Film is probably the best product for rust prevention.

Thanks!

 

[cucvrus]

National Coatings and Supplies - RUSFRE
I have been using this companies products for 40 years. Great old school stuff that works and won't fail. It looks great when applied and does not transfer when dry. Remains dry and tack free. Good Luck.

 

[Carolina1010]

RP-342 heavy
I'm no expert, but I've bought 40 year old rifle parts simply placed in a cardboard box with some cosmoline soaked paper loosely wrapped around it with no rust in water damaged boxes....... that wasn't the heavy mix but same stuff......it is thick and kinda waxy, and easily replaced if repairs need doing

RP-342 "HEAVY" Military-Grade Rust Preventive Spray

BESTSELLER - Our Strongest, Longest-Lasting Cosmoline Aerosol. Trusted by Industrial, Government, OEMs, DIYers & Armed Forces. Satisfaction Guarantee + FREE Shipping!

www.cosmolinedirect.com

 

[glcaines]

RP-342 heavy
I'm no expert, but I've bought 40 year old rifle parts simply placed in a cardboard box with some cosmoline soaked paper loosely wrapped around it with no rust in water damaged boxes....... that wasn't the heavy mix but same stuff......it is thick and kinda waxy, and easily replaced if repairs need doing

RP-342 "HEAVY" Military-Grade Rust Preventive Spray

BESTSELLER - Our Strongest, Longest-Lasting Cosmoline Aerosol. Trusted by Industrial, Government, OEMs, DIYers & Armed Forces. Satisfaction Guarantee + FREE Shipping!

www.cosmolinedirect.com

I wonder if that stuff would be good to spray on the wire rope on a winch? When I received my M35A3 W/W it had very low mileage and the winch wire rope had never been unwound. The wire rope was sprayed the entire length with something like that RP-342 and the outer layer of wire rope on the reel was also sprayed to a depth of about 1/4 inch. The stuff smelled like creosote. I almost hated to unwind the wire rope the first time since it was in such pristine condition. Since then I've used the winch at least 50 times, mostly pulling logs, and haven't treated the wire rope with anything, but the original preservative is mostly still there, after years of service and no trace of rust.

 

[ehuppert]

I'm a fluid film user also! Not a big believer in undercoating unless applied over epoxy primer/paint which is over fresh media blasted metal!!!!

I generally soundproof the inside of vehicle. The 3M peel and stick is effective, and much cheaper than the Dynamat products. Have used both, and numerous others. My 08 hasn't been road driven since restored (pending bed or flatbed on the back) but with some limited plowing and use on the property is much quieter than before..... (3m, jute and carpet)

Also have used the Rusfre.... works well also.

Did apply undercoating to my front inner wheel wheels, but they were new, epoxy primered, then painted. More for noise than rust

Undercoating, paint, etc over ANY rust just seals it in and makes it go the other direction!!!!!

With that said, would suggest a "good" name brand product. Some of the bargain brands spray like crap and don't cover as well...

 

[Sharecropper]

I'm a fluid film user also! Not a big believer in undercoating unless applied over epoxy primer/paint which is over fresh media blasted metal!!!!

I generally soundproof the inside of vehicle. The 3M peel and stick is effective, and much cheaper than the Dynamat products. Have used both, and numerous others. My 08 hasn't been road driven since restored (pending bed or flatbed on the back) but with some limited plowing and use on the property is much quieter than before..... (3m, jute and carpet)

Also have used the Rusfre.... works well also.

Did apply undercoating to my front inner wheel wheels, but they were new, epoxy primered, then painted. More for noise than rust

Undercoating, paint, etc over ANY rust just seals it in and makes it go the other direction!!!!!

With that said, would suggest a "good" name brand product. Some of the bargain brands spray like crap and don't cover as well...

Thanks Hupp for your reply. I’ve pretty much decided on the undercoating product I’m going to use, however I am still up in the air regarding an interior insulation product. You say 3M Peel &Stick? Where would an old fart like me learn about that product?

 

[ehuppert]

3M 08840. Easy to use, especially if it's softened in that good ole Southern sun! Easy to cut and form fit. Runs $80ish inc shipping for a box of 10 sheets. I did the cab floor and up the rear cab wall. Also did inside the doors! (Doors close with a thunk now) Gets rid of lots of the resonance and tinny sound.... I may have used more than one box, not sure as I always have some left overs from the job before! Generally use this, or dynamat depending on the scope of the job!

Really quite unlike my younger military days when we used cardboard on the floors in dueces, jeeps and cucvs, etc during the winter.... Getting soft in my old age!

 

[Sharecropper]

3M 08840. Easy to use, especially if it's softened in that good ole Southern sun! Easy to cut and form fit. Runs $80ish inc shipping for a box of 10 sheets. I did the cab floor and up the rear cab wall. Also did inside the doors! (Doors close with a thunk now) Gets rid of lots of the resonance and tinny sound.... I may have used more than one box, not sure as I always have some left overs from the job before! Generally use this, or dynamat depending on the scope of the job!

Really quite unlike my younger military days when we used cardboard on the floors in dueces, jeeps and cucvs, etc during the winter.... Getting soft in my old age!

Thanks !

 

[MarcusOReallyus]

I believe if I was going to be getting my truck wet and nasty every weekend like some half-cocked teenager, I would probably buy and use that product.

I think I'm confused..... If it doesn't rain where you are, why do you need undercoating?

 

[Sharecropper]

Sound reduction. The only reason.

 

[nyoffroad]

National Coatings and Supplies - RUSFRE
I have been using this companies products for 40 years. Great old school stuff that works and won't fail. It looks great when applied and does not transfer when dry. Remains dry and tack free. Good Luck.

We used this stuff when I started doing auto body work in 1983, I know of at least one car that I undercoated is still looking good and pretty much rust free. It was the bosses mother in laws and has since been passed down to a grand daughter and the only rust I saw was a bit just creeping up on the wheel opening pinch welds and inside the wheel wells where it had gotten worn away over the years.

 

[frank8003]

Daddie had His 65 Plymouth Valiant undercoated and His 1970 Valiant too.
New Jersey salt rots it all.
Neither one ever rotted away from the underside.
It was 23 bucks for the 65 and 29 bucks for the 1970
Dealer option
They just sprayed tar up into everything

 

[cucvrus]

Newer vehicles have come a long way in design and rust resistance. The problem is the road chemicals they use now are always a few steps away from the vehicle manufacturers. That liquid road salt is nasty stuff. I see the heavy stainless steel is stained on the state trucks that are dumping that stuff. Part of the problem is they pretreat the roads with the liquid before the storm and continue to dump salt and other deicing chemicals during the storm and during the melt freeze time. that liquid gets in everywhere and dries only to be reactivated when the rain and other waters hit it. Hidden deep inside the body panels. On a quiet night in Jonestown you can hear the vehicles rusting. That is old and new. New takes a little longer and old just never stops unfortunately. I look back and compare my Fathers 1969 K10. Bought new it was rusted thru in the cab corners, rocker panels, and cab mounts. That was 1977. So the play remains the same and only the vehicles have changed. Didn't much matter by 1979 it was ready for the scrap pile. 2 years of wheeling it and having a wild man behind the wheel done it in. I've known fella's like that.