How much rust can under-body spray stop?

[ovrszd]

Ray's post above is very thorough. It details what needs to be done to get the best protection available.

Sadly, that's all you are getting is the "best available".

Where your vehicle needs protection you can't access.

I contend rustproofing/undercoating is "snake oil".

If you want to extend your vehicles rust proof years be diligent about cleanliness. If, when you are done washing your vehicle, you are still clean, you just wasted your money in regards to protecting your vehicle. If you wash your vehicle without putting a knee or hand on the ground in the process, you wasted your money. If you used an Automatic Carwash, you wasted your money. Your vehicles chances of survival are dependent on your diligence. When was the last time you washed off the top of your fuel tank????

 

[Btown]

So my 2003 F250 is not going to pass inspection this year with frame rot among other things :thumbdown:. I'll have to replace it with another used 3/4 ton truck ASAP. My plan had been to wait another year and import a very lightly used truck from Down South and then religiously undercoat it. That is not an option now and will have to look locally. My budget will also likely dictate a 4-8 year old truck. Around here that means some rust will already be present. My question is how much rust can be halted without extensive prep work or even disassembly first? I'll go to a professional place to get it done. Before I moved Up North 6yrs ago I thought I knew what rust was. I had no clue how quickly it can eat a vehicle up!

Buy a all new aluminum truck, my 01 F250 needs new doors. Already put a new bed on 2013 style. I don't have frame rot, but frame is rusty. I'm hoping to keep it two more years.

 

[deezler]

Oof, this thread is not giving me much confidence for my currently rust free 2003 Sierra 2500HD. I just bought it last fall and this winter was pretty mild, so required limited road salt usage, thankfully. But every time the truck did get salty, I would go to the nearest quarter wash with several dollars of quarters and just go to town on the underside of the truck. Getting the Salt and dirt off quickly seems the best prevention method, IMO.

I was ready to blow $500 at Ziebart on undercoating right when I bought the truck, but hesitated as money was tight. Now I'm not so sure what to do.

 

[dickfoster]

So my 2003 F250 is not going to pass inspection this year with frame rot among other things :thumbdown:. I'll have to replace it with another used 3/4 ton truck ASAP.

My plan had been to wait another year and import a very lightly used truck from Down South and then religiously undercoat it. That is not an option now and will have to look locally. My budget will also likely dictate a 4-8 year old truck. Around here that means some rust will already be present.

My question is how much rust can be halted without extensive prep work or even disassembly first? I'll go to a professional place to get it done. Before I moved Up North 6yrs ago I thought I knew what rust was. I had no clue how quickly it can eat a vehicle up!

If rust is there undercoating will not stop it but could actually make is worse. Undercoating protects metal from rusting but providing a barrier between water, road salt etc. from ever contacting the steel and having corrosion set in. If you want something used but rust free get a used truck out of a dry state like Arizona or California. If you have rust already, put some rust conversion coating on it first then apply the undercoat. Heck maybe rust conversion, then paint, then undercoat. Too much is better than too little if your area has a lot of road salt used in the winter months.

 

[Luke'sScreenName]

Thanks everyone, especially Ray, who has responded so far.
I may (likely) end up buying a new 2016 F250.

My plan is to take it to this place:

NH Oil Undercoating | "The Good Stuff!"

Viewing window in the shop. All owners inspect on the lift at the end. Focused on being thorough. Use 360deg sprayers on tubing to get into the frame.

What do y'all think?

 

[dickfoster]

Try this stuff and let us know how it works...

Stop Rust with POR-15ｮ - We Know What Permanent Means!

I have a rusty truck I'd like to try it on, but I want some other guinea pigs to try it first.

I tend not to believe those people. I used POR15 on my off roader when I was doing the axle swap. Then when I went to do the brakes I found that just brake fluid strips that stuff right off. For what is supposed to be an automotive coating that ain't sayin much. I figure I wasted my time doing all the prep and stuff with POR15 products and would have been time and money ahead just using rattle can RustOleum. As they say, live and learn.

 

[ray66v]

If rust is there undercoating will not stop it but could actually make is worse. Undercoating protects metal from rusting but providing a barrier between water, road salt etc. from ever contacting the steel and having corrosion set in. If you want something used but rust free get a used truck out of a dry state like Arizona or California. If you have rust already, put some rust conversion coating on it first then apply the undercoat. Heck maybe rust conversion, then paint, then undercoat. Too much is better than too little if your area has a lot of road salt used in the winter months.

Keep in mind, for metal to oxidize, you need oxygen.

Anything that provides a barrier between the environment, and the metal, even if the metal has started to corrode, will help slow down the process.

Most late model trucks do not have heavy scale rust underneath. Generally, I see frames that have surface rust, which would not require much if any prep.

If it was heavily scaled, with layers flaking off, undercoating could present the possibility of helping to trap moisture in some small places. However, it's going to do that anyway. And, you aren't going to get much out of it as far as lifespan at that point, regardless.



One more point I'd like to make is, panels that are part of the cabin, like floors, or quarter panels, do NOT rot out, from the outside in.

They actually always rot out, from the inside out.

Moisture from usually unknown window leaks, taillight leaks, door seal leaks, sunroofs leaks, and weather that causes wet carpets, condenses to accumulate in cab corners, and quarter panels, and rot them out, from the inside.

With the exception of the frame, and suspension components, as the bad underside sheet metal sometimes looks, it's generally not a problem.

 

[WilliamBos]

Ray's post above is very thorough. It details what needs to be done to get the best protection available.

Sadly, that's all you are getting is the "best available".

Where your vehicle needs protection you can't access.

I contend rustproofing/undercoating is "snake oil".

If you want to extend your vehicles rust proof years be diligent about cleanliness. If, when you are done washing your vehicle, you are still clean, you just wasted your money in regards to protecting your vehicle. If you wash your vehicle without putting a knee or hand on the ground in the process, you wasted your money. If you used an Automatic Carwash, you wasted your money. Your vehicles chances of survival are dependent on your diligence. When was the last time you washed off the top of your fuel tank????

Spraying like Krown is far from snake oil, it does work. I wash my truck 2 or 3 times over the winter, the water at the car washes is filtered and reused when you wash. A certain amount of fresh water is added, but you are washing your vehicle with salty water.
Krown won't spray a muddy filthy vehicle, if it's bad they'll tell you to wash it, then getting it back, doing the Krown during the summer is highly recommended.
Fuel tanks are plastic of some form, washing the top of the sender is all that's needed.
A good early summer bath to get it clean, then a trip to Krown is the best way to save your vehicle.

 

[ovrszd]

I've never heard of car washes recycling their waste water??? Not saying it isn't so. I've just never heard of it. I would not frequent such an establishment.

My stance is Krown or any other commercial undercoating/rustproofing applicator will not apply the product in the necessary places. They can't without some disassembly. And I'm betting they don't do that.

My metaphor concerning the fuel tank was that 95% of vehicle owners have never saw the top of their fuel tank. 90% don't know whether their vehicle fuel tank is plastic or metal. Point being, if these estimates are true, then how much of the remainder of the underside of their vehicle have they never washed? When was the last time you washed your truck's transmission and T-case if 4wd??

If an owner can answer yes to all these things and clarify that they wash all components of their vehicle, their need for coatings is minimal, whether those coatings are "snake oil" or not.

 

[tcartwri]

Ray's post above is very thorough. It details what needs to be done to get the best protection available.

Sadly, that's all you are getting is the "best available".

Where your vehicle needs protection you can't access.

I contend rustproofing/undercoating is "snake oil".

If you want to extend your vehicles rust proof years be diligent about cleanliness. If, when you are done washing your vehicle, you are still clean, you just wasted your money in regards to protecting your vehicle. If you wash your vehicle without putting a knee or hand on the ground in the process, you wasted your money. If you used an Automatic Carwash, you wasted your money. Your vehicles chances of survival are dependent on your diligence. When was the last time you washed off the top of your fuel tank????

You live in Missouri. Thanks for the input.