Reader Question: Post-Hoc Rustproofing?

Here’s the latest reader question, along with my reply!

Tom asks: I had a great 2000 LeSabre that rusted out last year. There were rust holes in the rear frame and the rear shock tower connections were deteriorating.  I wanted to keep the car, had 90, 000 miles on it, Redline synthetic oil in the crank case, the trans, the power steering and I figured I’d get another 50,000 or more trouble-free miles.

I blame the brine that the government is spraying every time a freezing forecast is put out. Is “rustproofing” an option?  I have unearthed Krown Rustproofing https://www.krown.com/en/   and Corrosion Free https://corrosionfree.com/

Do you have any information on either? Is it worth the money? Does it work? Will it crap up the engine or anything else? Thanks.

My reply: I’m not specifically familiar with either of these two companies; but I am startled to hear about your Buick suffering that degree of rust – structural rust – so relatively soon… for a modern car.

Even in the way-past, the Dark Ages of the 1980s and prior – a car generally didn’t become structurally unsound that soon unless it was driven in New England or some other such area where the winters are long and hard and they get the Salt Bath for months on end.

Your Buick was built during the Modern Era of car design. Much better anti-corrosion measures (including primer/paint process) at the factory and the general build quality was (and is) so much better that the nooks and crannies and loose trim and so on which provided places for water – salty water – to leach into and eat into the car’s guts are largely not there anymore. Or not nearly as bad.

But your car still rusted.

Did you wash it – or run it through a wash – regularly during the winter/salt months? This is important to do. Especially the undercarriage/wheelwells.

Some counsel spraying down the underside of the car with oil (diesel, too) as a barrier to rust. I’ve never done this myself, except inadvertently – with two-stroke motorcycles – and in that case it did work. Those oil-soaked/covered bikes rusted much less and sometimes not at all compared with others. But it’s messy!

I would be cautious about any after-the-fact rust-proofing treatment, which may actually accelerate rust by trapping moisture already present. It’s my understanding that any additional rust-prooofing measures should be done when the car is new and hasn’t yet been exposed to moisture. Regardless, it is imperative that it be desert dry before anything that will permanently seal metal from the world is sprayed on the areas to be treated. If not, you may be locking moisture (and salt) in.

Which isn’t good.

I will look into the links you provided and try to suss out more info!

. . .

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