Undercoating on a new vehicle

[dodge man]

I’d say Fluid Film or Krown yes. Undercoating no. Undercoating is almost like bed liner and is more likely to cause problems. Undercoating was and is really more for sound deadining than any thing else.

 

[RandyT]

Check out a few videos from Eric on South Main Auto on Youtube and you will get what happens to rustproofed vehicles in NY. Peels off in big chunks with thick rust under it.

 

[LouNY]

Check out a few videos from Eric on South Main Auto on Youtube and you will get what happens to rustproofed vehicles in NY. Peels off in big chunks with thick rust under it.

I just watched part of one of his videos, that GMC had that coating done over previous rust and or salt accumulation without being cleaned and dried.
Undercoating properly applied to a clean undercarriage will not result in that crap.

I have had vehicles with various undercoating and corrosion prevention products and when properly applied they all help, good undercarriage washes are
a big part of corrosion prevention.

The quality of the steel or lack of also has a lot to do with it.

Manufactures don't want vehicles to last so poor designs, difficult to repair, inaccessible sensors, requiring cab remove to work on an engine, requiring transmission removal to change a timing ring or sensor. On top of tissue thin sheet metal and frames built to hold snow salt and other crap.
Makes for expensive vehicles with short lifespans.

 

[JJZ 109]

I had a truck undercoated a few years back. It supposedly was an $800 value package. I only paid $100 for it at a charity auction. Good thing. Most of it had fallen off within a year. But that probably says more about the prep than the product itself. But the smell of that stuff was terrible for about a month after application. Nothing I'd ever do again, especially at full shot price.

 

[RalphVa]

I've never done it to a new vehicle because of the issues noted. However, Toyota did a recall on our Tacoma and did it for us.

For some reason, the Japanese have not caught onto how to stop rust. Think the German and American car manufacturers have, but, no, to the Japanese. They also seem to put their oil filters still underneath. They just don't get it, but otherwise build fine vehicles. That's all we have now.

Ralph

 

[ray66v]

For some reason, the Japanese have not caught onto how to stop rust. Ralph

I work on all vehicles. I can't say that current Japanese cars rust more than the rest. In fact around here, they may do a little better.

Aside from a tendency of the Japanese to use a slightly thinner gauge sheet metal, I don't currently see any substantial differences in the way the Japanese build their cars.

Thickness isn't everything. How long a panel lasts, has more to do with the quality of the steel, and the quality of the corrosion protection, (i.e. internal sealants, galvanizing, and paint system), than the thickness of the metal.

They all know that certain things they do, like the use of rubberized foam sealant, can cause panels to rot. They all still use it. Some in ways that could be considered malpractice, since, it's has been known for decades, it will cause corrosion to occur if used there.

It would not take a heck of a lot to build bodies that would last a lot longer. Thicker layers of zinc galvanizing, internal cavities coated with rustproofing prior to assembly, and better drainage for condensate, would go a long way. There just isn't any incentive to do it.

 

[dnw64]

It would not take a heck of a lot to build bodies that would last a lot longer. Thicker layers of zinc galvanizing, internal cavities coated with rustproofing prior to assembly, and better drainage for condensate, would go a long way. There just isn't any incentive to do it.

I had an '85 Chevy Astro van. At one point I scraped a rocker panel with the corner of my plow and thought "Oh boy, I out to get that at least primed ASAP" as it was dented and down to bare metal. However, it was winter, and as the weeks wore on with no sign or rust I took a closer look and could see that it was some heavy galvanized action going on there. I sold it at least 5 years later having never done a thing to it and there was not the slightest bit of rust (anywhere on the vehicle that I could see). It was over 10 years old at the time.

I later bought a '98 GMC Safari (same van, different badge). about 8 years in we had a near catastrophic incident in which both brake circuits failed within seconds of each other due to the brake lines being rusted out. When I sold it about two year later it was pretty much a Flintstone mobile.

So, yes - I agree that the quality of components and process can make a huge difference (both vehicles had been equally oil undercoated).

 

[denchen]

Waxoyl do a clear and a black. I think the black is by far the best. Years ago, when cars used to dissolve in front of your eyes, a guy I knew always used to spray the oil he drained out of his engine all over the bottom, and his were rust free
.

 

[Redbug]

a guy I knew always used to spray the oil he drained out of his engine all over the bottom, and his were rust free
.

Chainsaw bar oil works well, too. It clings better and you get a good layer after you drive down a dry dirt road.

 

[ray66v]

I knew always used to spray the oil he drained out of his engine all over the bottom, and his were rust free.

People have trouble accepting this, but the floor of a vehicle never rots out from the outside in. It may get rusty. But, when a floor gets holes in it, it's always because there is a water leak.

May times those leaks are hidden. The windshield, back window, or cowl can have a leak that is only given away by a slight musty smell in the vehicle. And, damp carpeting when the rest of the floor is dry.

So, spraying the underside of the floor with oil, isn't critical.

If you took the time to coat the inside of the frame rails and cross members underneath with oil, that could help. But, oil will wash away over time. And, when you go to reapply the oil. there may be dirt that cakes up inside cavities which can prevent you from keeping the metal protected.

If you used a good quality asphalt based undercoating, (same level of effort), you won't necessarily ever have to reapply it.