Rust Prevention detail vs coatings?

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Jun 13, 2022
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Friend was doing a comparo between his old 2 decade 4R vs his factory fresh 4R that he picked up recently. Being they are in Chicago/Rust belt I was expecting a rust bucket frame underneath it but surprisingly nothing of the sort. He claims it was never undercoated just religiously pressure washed exterior and undercarriage periodically over its time and left outside as it was their DD.

i see alot of folks talk about undercoatings, but can adhering to a strict car wash regimen eliminate the horror rust stories?
 
How practical is a strict car wash regimen? Here, I'd daily drive to work, and if the roads were salted, it sat coated in that all day while parked at work. When I drove back home, I suppose I could stop at a car wash, or when I get home, spray the undercarriage but it's not always practical, particularly if it's below freezing and that results in an iced driveway. I could put ice melt on the driveway but then even my driveway subjects it to salt deterioration.

My best guess is the friend had road crews using something like beet juice instead of a salt to melt the roads, that it was not driven for 20 years worth of winters on salted roads without something more going on, even if that something was only a good factory undercoating.

However, define "rust bucket frame". I have a (previously used as a) daily driver older than 20 years that still has a safe frame, but it's not like there isn't a lot of rust to be found. Floor pan developed a big hole, brake lines needed replaced, rocker panels and dog legs got replaced and now need it again. Lower rear shock bolts shear off every time I attempt to remove them, sway bar link bolts rust through, and to some extent I just have to accept it if not willing to put it on a lift and undercoat every year or two because there's no way in your driveway without a lift, to practically coat (or wash) every nook and cranny. However what you can do, is coat things in silicone grease when you replace them. They'll get ugly grimy looking but take a lot longer to rust out. I mean fasteners in particular, then there's using NiCu line for brakes.

Ultimately, I just want the rust to not be the reason to send a vehicle to the graveyard before some other failure like engine or tranny happens, where repair exceeds the value of the vehicle. At the same time, any vehicle reaches the point where it seems like every few months, it's nickel and dimeing you and you just want to drive something that doesn't need that much attention, and rattles/squeaks less. I'd keep a 20 y/o 4R for the utility of hauling/towing, or use on salted winter roads to save a daily driver from it, but agree with your friend to get something newer to daily drive otherwise.

Lastly there is value of time and cost to maintain as a perspective. Suppose value of time and cost to maintain ends up as $150 a year. After 20 years, that's $3000. If the vehicle is no longer worth much more than $3K, it doesn't seem worthwhile. Here's a case where covid related shortages and escalating new vehicle prices due to tech are a wildcard, but in the past that rationale made sense, that it's not wise to spend more to keep a vehicle than it's insurable value is worth, or you just end up going to great lengths trying to, then some texting teenage driver runs into you and totals it anyway.

Just sayin'... life is short, how much work to put into a vehicle worth little once it is 20 years old? Makes sense if you look at it from the green perspective of not polluting by buying a new vehicle, or makes sense if you DIY all the work to squeak by with far lower repair expenses, but that is a highly subjective decision, and can change as you get older. The older you get, the less you want to be babysitting *anything*.

Back to the point, do I want to spray the undercarriage of my vehicle every time I drive in freezing weather, winter slush? Heck no.
 
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Friend was doing a comparo between his old 2 decade 4R vs his factory fresh 4R that he picked up recently. Being they are in Chicago/Rust belt I was expecting a rust bucket frame underneath it but surprisingly nothing of the sort. He claims it was never undercoated just religiously pressure washed exterior and undercarriage periodically over its time and left outside as it was their DD.

i see alot of folks talk about undercoatings, but can adhering to a strict car wash regimen eliminate the horror rust stories?
I agree with your friends methods of pressure washing the under carriage. I won't give you a long meaningless explanation but getting the salt off works. Been practicing it myself on my 87 for a long time now..
 
I've been pressure washing under my 99 accord since new.no rust at all...just about like new ..i pressure wash out in the drive way in what ever weather there is ...i cant stand the idea of salt under the car or on the car
 
Unless you have a heated garage with a drain the wash method isn't feasible here. That's why I prefer coating.

Not to mention a properly applied coating stops salt from ever touching bare metal.
 
In Michigan, you still have to be concerned about all of the boxed in body areas: pinch welds, door bottoms, rockers, fender edges, etc.. Salt mist penetrates those areas and the vehicle rusts from the inside out. We also have week-long spells with salty wet roads. But, people have anecdotal stories that constant washing works. To each their own.
 
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I don't like the idea of washing, who knows where it might push that salt. Lots of areas that won't get good flow of water. Where will salty water be trapped?

My garage stays too warm, I have puddles all winter now. I think my cars going forward will last less long as a result, in my old house they stayed outside and so as long as it was below freezing, I don't think much rust damage was occurring. Oh well. My best bet is undercoatings now. At least that is my plan...

End of the day, the rest of the car is wearing too. Cars can age out. Me, I'd like to be happy to see something go, all the rubber bits are dried out, various bearings slowly wearing out, I did what I could but rust filling creeping up... that shiny new car on the lot is just too tempting this year... After 10-20 years of good service, time to move on. Assuming the car wasn't wrecked before then.

Or just move south.
 
In Michigan, you still have to be concerned about all of the boxed in body areas: pinch welds, door bottoms, rockers, fender edges, etc.. Salt mist penetrates those areas and the vehicle rusts from the inside out. We also have week-long spells with salty wet roads. But, people have anecdotal stories that constant washing works. To each their own.
This is the #1 reason cars rust out. Surface rust is ugly but really nothing. Catastrophic rust comes from the inside out.

I honestly think we put way too much importance on exterior undercoating and way too little on an internal wax/ oil based coating.
 
I can get at least 10 years out of my vehicles before they have any rust at all. If I see it coming through it's time to sell. There are some years where they only salt the roads a couple times and other years such as this year they salt on a regular basis. I do believe products such as fluid film help a lot to prevent rust. I hit the rear quarter panels with a quick spray of fluid film on my Honda Civic every couple weeks and run it through the automatic car wash almost daily. I also believe regular washing helps substantially too. Use both methods and you are covering the bases about as good as possible.
 
Both methods will work because it’s the salt that does the damage, get rid of the salt or impede it’s contact with metal and there will be no rust.

Undercoating is more practical. Apply it once a year, or every few years and forget about it, maybe touch it up every once in a while.

Washing, provided you actually can get to all areas under the vehicle will work as well. But that requires a lot of effort, equipment and your own garage or driveway.
 
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Driven up here in WI most of its life - my 05 Liberty. No rust. Washed at least once a week during the winter, and recently started fluid filming all the holes/nooks I can find underneath - with a 3ft long piece of tubing to really get it in there. Sand and paint any surface rust. So it is possible to live in the salt belt and keep a vehicle clean and rust free.
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This is the #1 reason cars rust out. Surface rust is ugly but really nothing. Catastrophic rust comes from the inside out.

I honestly think we put way too much importance on exterior undercoating and way too little on an internal wax/ oil based coating.
Surface rust eventually equals a hole. That's the begining stage and shouldn't be under estimated.
 
Surface rust eventually equals a hole. That's the begining stage and shouldn't be under estimated.
We'll just have to agree to disagree on that one. The amount of time it would take for surface rust to turn into a hole is so long it's basically irrelevant in my opinion.
 
Wow!
I can't believe that no one has mentioned a regular trip to the drive-thru carwash.
I have a subscription to Crew Car wash and I include the underbody wash.
No rust.
 
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We'll just have to agree to disagree on that one. The amount of time it would take for surface rust to turn into a hole is so long it's basically irrelevant in my opinion.
If agree. While I would love to have my vehicles looking brand new for 15-20 years, I’m a realist and I know there comes a time of diminishing returns. While the vehicle is new, the extra effort seems worth it, but as it gets older and diminishes in value, that same effort looses its proposition IMO.

And then when you get to 15 year mark or so when even a small accident can total the vehicle, a little bit of rust or varnish under the valve cover is absolutely inconsequential IMO.
 
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