There is no undercoating!

I just discovered the 2005 Buick Century has no undercoating. Is undercoating normally included with a new Century? Should I use high temp. black paint as an undercoating?

Undercoating is counter productive. Leave it alone.

The standard factory treatment is light years better than what you got in the past. As mentioned, applying under coating will trap moisture later on which will actually increase corrosion.

Years ago I used to go to an “oiler” who sprayed used motor oil to the underside of my 70s cars. That helped at the time, but is now illegal and not necessary

Ziebart was a big name in rust proofing, but after 1976 cars had to have a rust warranty. This made additional undercoating unnecessary.

I don’t think any cars have ‘undercoating’ any more. Galvanized steel and design improvements have eliminated most of the need.

This is the same guy who wants to use a stop leak in his brakes.


If your undecarriage isn’t rusting away, you don’t need undercoating

I agree with @Docnick . . . I can’t remember how many horror stories I’ve heard where the undercoating was the only thing holding the car together . . . BECAUSE the undercoating itself trapped moisture

@db4690 Undercoating was always an after market item. Car manufacturers claimed cars did not need undercoating. Properly applied, when the car was brand new, Ziebart coated the inside door panels as well as the underside and the trunk. It added considerably to the body life.

But many applications were applied to used cars, where a poor application had the opposite effect.

@db4690 Undercoating was always an after market item.

No it wasn’t…and it’s being done today by many manufacturers. My 05 4runner and wifes 07 Lexus both have FACTORY undercoating.

I agree. If the car doesn’t have factory undercoating, don’t add it. Metal treatments including galvanizing, priming, painting and using metals that are a little more rust resistant as well as better drainage and engineering are suppose to help. Factory undercoating is used as much for sound proofing as anything else. I can understand a little additional on off road vehicles that need a little extra protection. Bottom line though, you need to do a little preventative maintenance yourself as most bodies rust first in other areas other then flat exposed surfaces that drain well. Your door drains, sills and rear quarters are a much bigger concern. Generally, body parts are " allowed" to rust after so many miles and so much lack of care. There are biodegradable oils you can apply and frequent inspections the owner should do to lengthen body life. Most of us just don’t bother as the average car can go ten good years.

Agree. In the old days you could buy the factory undercoating option which was a rubbering coating. As this deteriorated though, it held the water and salt in and accelerated the rust. Its better to now just leave it alone with the factory treatments. Unless of course you want to oil it up as Dagosa does.

Agree. In the old days you could buy the factory undercoating option which was a rubbering coating. As this deteriorated though, it held the water and salt in and accelerated the rust.

Actually NO…Properly applied undercoating and rustproofing does NOT promote rust. It’s been PROVEN to prevent rust and works GREAT.

The problem is applying it properly. I’ve seen cars in upstate NY that were rustproofed and lasted years beyond the same car that wasn’t rustproofed. I know a family who’s Dad and Son bought the same car…The Son had his rustproofed and his Dad didn’t. After 4 years the Dad’s car had rust through holes in several spots…while the Son’s car didn’t show it’s first sign of rust until it was 10 years old.

My wife bought a brand new Datson 510…The hood rusted out in 2 years. I bought a new hood…and before I had it painted…I put on a nice layer of rubberized undercoating on the inside of the hood. When we sold the car some 6 years later…the rest of the car was rusting out badly…but the hood was still EXCELLENT.

Undercoating got a bad name because of the way it was applied…Undercoating was left to the grease-rack crew, and in that group, the low man on the pole was assigned the undercoating work-orders…Typically, this guy did not give a fig whether your car rusted or not…It was a hit or miss application at best…Remove the wheels and tires so you could get inside the fender lips, the place where body-rust usually starts? Not a chance…Too much work…

Our 1976 Ford Granada, bought used and 2 years old, had undercoating and had the inside panels done as well. This was the first year Ford treated the lower 8" of the body with an anti-chip coating and then painted over it. This car turned out to be a rust bucket, probably because the previous owner took too long to have the car done and did not use Ziebart or equivalent quality treatment.

That was our last Ford; I had to get rid of it with only 108,000 miles on it.

IMHO, both are right. If the undercoating is properly applied and properly repaired when broken, it works great…but. Most undercoating drys out and cracks with age, especially after market and can be a problem if moisture is allowed to penetrate. Some factory installed undercoating if protected and repaired properly, can last a long, long, long time. The biggest problem with after market under coating is it’s indiscriminate use and clogging drain holes. There are just too many examples of shoddy application of undercoating and improper maintenance to recomend it to the average consumer unwilling to dothe proper application and maintenance. NOTHING is a fool proof as biodegradable oils and grease. The problem is, we live in a fix it and forget it world and are looking for one time fixes. Short of stainless steel, and that’s not forever, nothing works forever.

But, properly maintained…rust can be forstalled, not for years, but for DECADES by anyone ! IMHO though, undercoating creates a barrier to this proper maintenance after a certain number of years. I also would not use undercoating on some vehicles on areas that are likely to sustain frequent underbody abuse where it can be damaged and not repaired. A hood application seems like an ideal use for this material, both for rust prevention and sound deadening.

Btw, just the idea that some one applied rustPROOFING and it still rusted after ten years tells you that it wasn’t rustproofed…just rust forstalled and it will be harder to do any rust prevention from there on out. It also does nothing for inner fenders, rockers and rear quarter panels that rust form the inside from poor drainage which all cars eventually suffer from… Only oils can penetrate after market there.

I think we are talking different eras. I was talking about undercoating in the 60’s, which was a rubberized coating on the chassis that would crack and peel and trap salt and water. Rust proofing such as that done inside door panels with a waxy material worked very well, but that wasn’t undercoating in the old days. My Riviera was rust proofed, plus galvanized, and took 20 years to start rotting out.