Body Rust ….Magnesium Chloride

[flash4490]

I have a 2003 Sub Outback. I waxed it a month ago was surprised that I found extremely small dots of rust on the back hatch door, and under the driver’s and passenger’s front door handles. We took it to a body shop and they looked at it with a magnifying glass and found microscopic dots of rust all over, even on the roof. This was strange as we live in Colorado were rust usually isn’t a problem, we garage the car, and had another 12 year old Sub wagon which had almost no rust issues.

We thought it was a defect in the paint job, so we took it back to the dealer and ask them to fix it. The Factory Rep said they would take it to a detailer and have them get the rust out. We thought it would need a whole new paint job.


My first question is: Have you heard of detailer’s being able to get the rust out? If so is this a good solution or does it merely put off the problem for a while. It seems to me you would need to repaint the whole car to make sure you got the rust out. It seems if the factory rep is just getting a low cost temp solution to the problem and later the rust will come back and the car will be too old to have the dealer pay.

Second question is: I have heard there are these types of rust problems where they use Magnesium Chloride on the roads. How do you protect your car from this?

[Accumulator]

This is more common than some might think, and it bugged me for years as I've had a bunch of white and silver vehicles where it really stood out (including a white Subaru Outback).

The specks of rust are commonly referred to as "rust blooms" and are almost always the result of ferrous contamination (such as rail dust from transport, or industrial fallout, or particles from the blades of snowplows, or bits of brake rotor, or..well, you get the idea). The contamination starts to corrode (rust) and when it gets bad enough you can see it with the naked eye.

Claying and paint cleaners work to some extent. Sometimes they do a fine job and that's that. But sometimes, especially once the rust has achieved a good bite, they only offer a temporary fix; the rust comes back because the paint cleaners/clay doesn't get it all. The tiny bit of oxidized ferrous contamination that's left behind starts the process up all over again.

When paint cleaners and clay don't work, you need a decontamination system, which unfortunately Meguiar's does not offer. There are two sources of these systems that I'm aware of, but I don't want to post links to them here as it would violate forum policy. The companies that make them are named Automotive International ("AutoInt") and Finish Kare ("FK1"). These systems use a mild acid for the second of their three steps and this acid burns out the rust. I've used the AutoInt system and it worked (and worked *safely*, I even used it on my beloved S8). Claying or using a bug sponge while the acid is dwelling will increas the effectiveness.

Not something you'd want to do very often (I've only used it once per vehicle), but sometimes this approach offers a drastic solution to a drastic problem.

[flash4490]

Thanks,

We do live next to the rail tracks....