Feelings about undercoating in salt belt states

[SmaxxSmith]

Hey there, my fine peoples! I'm living in Michigan. I don't drive her in the winter. Undercoating. Many opinions on this. I want the opinions of the twins community. I'm scheduled for a ziebart tar based undercoat. Many say it traps moisture between the metal and undercoat and that it makes it tough to work on. I can see how that's possible. The other wax/oil based types seem to be messy (especially when working on it), collect dirt and debris and washes off quickly. I was thinking to have the tar based on the bottom and any other areas accessible from the outside. No holes cut for internal spraying. I'd be afraid that the same holes, despite the plugs, would increase the chance of water getting into areas that would tend to hold water longer. Hopefully it'll help a little for sound deadening too. How do you guys feel about undercoat and do you have any suggestions? What about condensation on cars in storage? Areas like in rocker panels? Ideas? Thoughts? anecdotes? Thanks!

[Spuds]

My opinion, you don't need it. The car already has a tough undercoat from the factory. Your subframes will get some rust, but undercoat isn't going to protect those bits anyway.

[StraightOuttaCanadaEh]

Go to a good place that won’t spray it all over the goddamn exhaust and springs, making your car stink for weeks

[Tcoat]

I am on the side of don't bother. The rust resistance of the modern car materials is miles and miles ahead of your average 70s Pinto or 80s Omni. After 4 harsh Canadian winters the only rusty spots I have are the uncoated fasteners and the front edge of my roof. Neither one of these would be helped by a spray on undercoat. The rest of the underbody looks like new (very dirty new but still new).
Cars in storage need to be parked where moisture is not coming up from below. Park it on a hard surface not in tall grass and all is good.

[gravitylover]

Don't bother, the stuff that will rust wouldn't really be protected by undercoating anyway unless you want to smell it burning off the exhaust for months and ruin suspension bits.

[DarkPira7e]

My car came from Texas with no factory undercoating. I get a Fluidfilm XP application every fall. Yes, it's messy and smells funny. I have no rust so far, so it's worth the $75 every year to have someone spray it on. I don't know if it's helping or not, but I've lost 4 of my favorite cars to rust holes in the floor I'm not risking it.

[SmaxxSmith]

This is going to be interesting! 3 out of the first 5 say don't do it. I think Ill put up the total yeas and nays after a day or so.

[Tcoat]

Originally Posted by DarkPira7e

My car came from Texas with no factory undercoating. I get a Fluidfilm XP application every fall. Yes, it's messy and smells funny. I have no rust so far, so it's worth the $75 every year to have someone spray it on. I don't know if it's helping or not, but I've lost 4 of my favorite cars to rust holes in the floor I'm not risking it.

My experience with rusted floors (keeping in mind many of my cars were from 1958 to 1970) has always been that they rust from the top down. Moisture inside the car did far more damage than moisture from under it.
Any car made from about 1990 back would be far more susceptible to rust as they just did not treat the steel like they do now. I had 5 or 6 year old 80s econoboxs that were rotted through in both vertical and horizontal surfaces since the steel was just so bad right from the start. I think that you will find that the floors and trunk base of these cars will last a long time without extra treatment.
I don't think treatment hurts anything (some will say it does) I just don't think it will help anything either.

[DarkPira7e]

Originally Posted by Tcoat

My experience with rusted floors (keeping in mind many of my cars were from 1958 to 1970) has always been that they rust from the top down. Moisture inside the car did far more damage than moisture from under it.

I don't think treatment hurts anything (some will say it does) I just don't think it will help anything either.

You're probably right, I think some of my issues have been from missing bolts that once held underpinnings, but fell out through the years without being noticed. Others may be from scraping on a rock or something, who knows. This is by far the newest car I've owned, my experience is with late 80s to pre ODBII cars. I'd still rather feel like I'm doing something rather than hoping I love this car too much to neglect it.

[computeruser]

I wouldn’t bother. Just get more frequent, and better-quality, car washes in the winter. The body colored painted surfaces under my 2015 still look just fine. Exhaust and stuff with black paint on it is still ok but less so, but that’s all easy to replace when compared to floors and sills and such.

[Dave-ROR]

If you do, use an oil/liquid coating instead of the older rubberized shit that just results in the car rusting out under the rubberized shit.

[SmaxxSmith]

Well, i guess what i should take from this is that we certainly are a divided group! LOL! I thank youz guyz for your opinions. I'm not sure it really gave me any direction though. I'm still unsure if i should do it or not. i better make up my mind though, the appointment for undercoat, detail and tint is in a two days! Thanks again!

[Tcoat]

Originally Posted by SmaxxSmith

Well, i guess what i should take from this is that we certainly are a divided group! LOL! I thank youz guyz for your opinions. I'm not sure it really gave me any direction though. I'm still unsure if i should do it or not. i better make up my mind though, the appointment for undercoat, detail and tint is in a two days! Thanks again!

It really boils down to there being no advantage in rust proofing any car made after the late 1990s. They have done a great job of using rust resistant materials since then and the parts that will rust will not be helped by undercoating anyway. There also is no real disadvantage to doing them either though. This is why you are getting such mixed messages.

[Lantanafrs2]

Just wash the salt off it regularly during the winter.