"Salt proofing" the undercarriage

[amarti23]

Does anyone know if there is some kind of seal I can have sprayed on my undercarriage to protect against salt? It's my first winter out here and I'm told they use salt and sand here in CO.

I wondered if there is an easier way to protect it from rust other then constantly spraying off with water?

Thanks guys!!!

[135Pats]

Very interested to see what people say...DC isn't exatly snow central, but the powers that be are VERY quick to throw down the salt, people around here freak out when the snow accumulates.

[euro2fast4u]

Rust needs 3 things, air, water, and steel. When you add salt you increase the flow of electrons that increase the speed of the deterioration of the metal. So how do you prevent that. Wash the salt off regularly, dry the bottom of your car, because you cant remove air , and then inspect monthly that none of your undercoating has been scratched off or chipped. As long as the under coating is intact and 99% of the time that's the issue. You wont have to worry about rust.

[KingOfJericho]

Yeah but I'm sayin' that TrueCoat, you don't get it - you get oxidation problems. It'll cost ya a heck of alot more than $500...

[euro2fast4u]

huh?

[mma600psi]

If you take a look under the car its very well protected with plastic guards underneath. I personally dont think its really required.

[Stohlen]

Colorado doesn't use salt. They use liquid deicer. Its blue, very similar to windshield washer fluid. Doesn't rust cars nearly as bad as salt.

[MaDoNiOn]

http://www.jigaloo.com/us/e_products_jigaloo.php

Maybe you car spray that underneath.

[JimD]

In the 1980s and earlier, cars were made of materials that were pretty susceptible to rusting. I lived in Pittsburgh, PA then and it was a real problem. Since that time, materials have improved (different steel alloys) as has weatherproofing. I still get back to PA occasionally and the difference in the appearance of older vehicles is pretty striking. I bought my first new car in 1988. I got stuck paying for a rust preventitive treatment. It was already on the car and was the only car they had at the rock bottom price they advertised. So I reluctantly paid. Even then I was convinced it was a rip-off and the salesman pretty much agreed with me. You can hardly find these third parties that do this any more.

On the subject of my bimmer, I noticed waxy goo coming out of the doors shortly after delivery. My understanding is that this is BMW's rust proofing.

If you have the option of garaging your ride or washing the salt off periodically those are good practices but the expectation you should have is that your car not rust itself to death regardless.

Jim

[1speedbike]

How long are you planning on keeping the car?

I thought BMW gave us a 12 year / unlimited mile rust and corrosion warranty. If you keep the car 12 years, it's gonna need a lot more than a de-rusting.

Also, some of the rust-proofing crap they spray under there tends to degrade rubber.. so if they spray your bushings a bit too much... eh. I'm not worried about rust. I live in NJ, and just give the car a semi regular bath in the winter. My coilovers aren't rust proof (and neither are most springs and shocks) and they are very exposed, so I would just check on those every once in a while to see if there's any surface rust.

[amarti23]

I plan on keeping it long term. I think you're absolutely right about the warranty about the rust. I do keep it in a garage at all times so hopefully that will help. I'll wash it off regularly this winter after it snows. Seems like global warming is really getting us this year. Had the top down this weekend here in CO cause the temp was 65*!! Thanks for the advice!

[Jmanscotch]

Originally Posted by euro2fast4u

Rust needs 3 things, air, water, and steel. When you add salt you increase the flow of electrons that increase the speed of the deterioration of the metal. So how do you prevent that. Wash the salt off regularly, dry the bottom of your car, because you cant remove air , and then inspect monthly that none of your undercoating has been scratched off or chipped. As long as the under coating is intact and 99% of the time that's the issue. You wont have to worry about rust.

Correction; oxygen (air), "electrolyte" (aka, water or soil or anything conductive) and "exposed/bare" steel.

Cars don't rot in southern wet climates like they do in snow/salty ones. That proves that water alone isn't something to worry about...though we all know a dry climate (Cali/Arizona) will see even less rust than Texas/Louisiana/etc.

Either get an undercoating (line-x, or others suggested here) to prevent bare metal exposure of the cars undercarriage or wash the car regularly to rid it of the salt. Even when you wash it, salt/water/grime/dirt/sand/etc collect in those tough to reach nooks and will cause problems, so the undercoating is really going to be your best bet if you're worried.

That said, cars corrosion resistant coatings these days goes pretty far. Unless you're planning on keeping the car a dozen years then it's not going to have problems while you own it, unless the car has had damage and the corrosion protection coating wasn't properly reapplied.

Also, I saw a post about BMWs 12 year corrosion warranty; that for full on perforation only. For it to be honored, BMW requires you to participate in an every 2 year corrosion inspection at the dealership (which you pay for)...so that usually don't help anyone.

Jake
Corrosion Engineer

[Stohlen]

Originally Posted by Jmanscotch

"electrolyte" (aka, water or soil or anything conductive) er

Water doesn't rust steel. The materials in the water do.

[Jmanscotch]

Haha, no; the water is only a conductive path for ions to flow. The 'materials' in water can accelerate or slow down the process. Same situation with soil/grime. The salt accelerates the process.

I have a degree in Corrosion Technology so we'll assume I'm correct. I don't mean that in a 'cocky' way, it's just there is so much misinformation about corrosion/rust out there because few people specialize in the field so I try to help clear some of it up.

[HeyMoe53]

I sometimes read a blog written by a gentleman named J.E. Robison, who specializes in servicing and restoring high-line vehicles (Rolls, Bentley, and such). His recent blog entry is basically an ad for a product named Waxoyl, which he applies in his shop.

The guy seems like he knows is way around high-end cars, so I thought it was worth mentioning. His comments about rodents chewing on wires are making me think about keeping comprehensive insurance on my 1, which is stored until 3/1

[Nkryptd1]

Originally Posted by Stohlen

Colorado doesn't use salt. They use liquid deicer. Its blue, very similar to windshield washer fluid. Doesn't rust cars nearly as bad as salt.

I second this comment as I've lived in CO all my life and know for a fact that we do not use salt here.

[amarti23]

Thanks! That's good to know!

Thanks everyone for all the advice! I'm a FL native and have never had to deal with snow like what I'm told Colorado gets. I'm just trying to keep my 1 looking and working great! Love this car!

[euro2fast4u]

Originally Posted by Jmanscotch

Haha, no; the water is only a conductive path for ions to flow. The 'materials' in water can accelerate or slow down the process. Same situation with soil/grime. The salt accelerates the process.

I have a degree in Corrosion Technology so we'll assume I'm correct. I don't mean that in a 'cocky' way, it's just there is so much misinformation about corrosion/rust out there because few people specialize in the field so I try to help clear some of it up.

Thanks Jake!

My i asked my father about electronic corrosion prevention as he used to also be a corrosion engineer. Thanks for the correction.

[JTBMW1]

The parts that are most suseptible to rust are the underneath chassis components- frame, A Arms, suspension parts, painted steel brackets and drive shafts. I used to undercoat the painted steel components when I lived up north. I used only a high quality undercoating spray from 3M. The only time I did not use undercoating, I used a high quality black paint- like Rustoleum- for drive shafts. I would always primer bare steel parts as well. The fenders are all very well protected since they are galvanized on the inside and protected with paint and primer on the outside. With the undercoating and frequent undercarriage washes, my cars and trucks stayed rust free- no rust at all on the undercarriage. I also used to touch up any bare, chipped or rusted spots underneath every fall while the weather was still warm. I never once had any issue with rust through on a fender and I always kept my cars well waxed to protect the outside. The undercoating was a really messy job and I am glad at least for the time being that I live in FL and don't have to worry about road salt and undercoating.

[bkbeagle]

Originally Posted by amarti23

Does anyone know if there is some kind of seal I can have sprayed on my undercarriage to protect against salt? It's my first winter out here and I'm told they use salt and sand here in CO.

I wondered if there is an easier way to protect it from rust other then constantly spraying off with water?

Thanks guys!!!

You may want to consider a touchless carwash with the undercarriage spray option. We have lived in Denver 20+ years (we are transplants from the South) and have owned 6 Bimmers & 4 Jeeps in that time. Never have had an issue with corrosion of any sort and all I have done is been fairly diligent about getting "touchless" car washes with every other fuel fill during winter.

One other thing to note is that regardless of the snow we get in the Metro area, the humidity level is still pretty darn low. Corrosion, with respect to automobiles, is not a significant issue in this region.

Welcome to Colorado and good luck!