I see a lot of trucks with body rust around the rear wheels, and a lot of cars with body rust behind the front wheels and below the doors.

I've been looking into trying to repair some rust on my car and the rust converters I've looked at recommend sanding down to bare metal before applying the rust converter. If you can apply it to non-rusted steel, why don't car manufacturers treat these parts of the car with rust converter at the factory to make them more corrosion-resistant? Or do they perform some sort of treatment and it simply cannot stand up to roads that are salted in the winter?

  • Rust converter is a treatment that reacts chemically with rust. It's not a preventive measure except insomuch as, by eliminating existing rust, you prevent it from spreading. Other preventive coatings are already used where appropriate. Apr 10, 2015 at 20:46

1 Answer 1


The manufactures take several steps to prevent corrosion.

  • Zinc coating to the bare steel at the steel mil
  • metal treatment
  • electrodeposition coating (E-coat)
  • seam sealers
  • chip-resistant coatings
  • Top Coats
  • Undercoating

Here is an illustration form Axalta Shinto Coating Systems

enter image description here

BMW as a video on this page that shows the whole painting process.

Nothing lasts forever, but most are warrantied between 5 and 10 years, even some up to 25 years.

The amount of time the vehicles corrosion protection lasts depends on the elements that the vehicle is exposed.

As for your particular problem take a look at POR15, POR stands for Paint over rust. If you follow the three step process you do not have to remove the rust or sand down to the bare metal. This stuff is GREAT, I have used it on many many vehicles, and many of the restoration shops swear by it.

enter image description here

  • POR-15 is great stuff ... it just doesn't like sunlight, thus the topcoat is very important if it's going to see the light of day. Apr 10, 2015 at 20:20
  • 1
    @Paulster2 Yes, they have a top coat now that's step 4 above. That provides UV protection. Apr 10, 2015 at 21:15

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