Will products like Echo-Guard protect my car from rust?

Dear Car Talk

Dear Car Talk | Apr 01, 1996

Dear Tom and Ray:

I recently purchased a product called Echo Guard with a new-car purchase. The product is supposed to substitute for normal undercoating and rustproofing. It theoretically prevents rust from developing on all metal surfaces by replacing the electrons lost due to the oxidation process. The dealership claims the U.S. Navy uses this product on its naval vessels to prevent rust. It has a small box with a flashing red light attached to the battery. Have you heard of this product or a similar one? Does it work? Please educate me. -- Gene

TOM: Yes, we've heard of these things, Gene. And the stuff we've read says that no, they don't work.
RAY: We've seen many articles about these devices. And studies show that they do work on ships, but don't work on cars.
TOM: Why? I don't know. It may have something to do with the fact that a ship sits in water all the time. So maybe if you park your car in a couple of feet of water every night, this Echo Guard will keep it from rusting. If it does, YOU can publish a paper and educate US.
RAY: So you may have been taken, Gene (although I'm sure the manufacturers of these devices will send us lots of information to try to convince us otherwise). But all is not lost. Even if this thing is bogus, you may still be able to salvage some of your investment.
TOM: Right. If you move that little box with the red flashing light to the inside of the car -- like somewhere on the dashboard -- you may be able to deter thieves by making them think your car has a burglar alarm!

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