Don’t let sleeping (or hiding) rust get you

The recent spike in usedvehicle demand has retailers and shoppers hopping to try to find the right vehicle at the right price, and has many of us looking into older vehicles we once might have steered clear of. There’s no problem with that, as long as the price and product is right.

However, this does introduce a few tire-kicking caveats — particularly to ensure you avoid buying a ride that has had its corrosion hidden with some quick repairs and a fresh coat of paint. If you’re only looking for a temporary ride and won’t be keeping it for more than a year, you may only need to be concerned with structural rust. But if you plan on keeping a used vehicle for several years, finding out if it’s got more corrosion than it should is a critical step in protecting your wallet.

Come prepared for shopping. Bring along a small, coated magnet to check body panels for the presence of filler. Coating the magnet in a protective layer such as masking tape reduces the risk of scratching the paint on something you don’t yet own. But before pulling out your magnet, make sure the surface you’re checking was steel to begin with. There are a lot of plastics and synthetic materials used in vehicle construction nowadays, not to mention aluminum which may be a metal but isn’t magnetic either. Another handy tool is a cell-phone selfiestick. It’s a great way to get detailed views of the bottom of a vehicle without lifting it on a hoist (which most retailers are hesitant to do anyway).

Concentrate on the areas that corrosion attacks first on most vehicles: the lower rear areas of the wheel wells, door bottoms, lower edges of fenders, rocker panels, and quarter panels. Pop the trunk or liftgate and take a close look at the inner quarter panels and spare-tire well (keep in mind on some vehicles, plastic trim panels will be in your way and few sellers will be interested in letting you disassemble an interior). With your phone, snap a series of pics from the front to the rear of the undercarriage paying attention to main structural components as well as floor pan metal.

On a vehicle that doesn’t have the tell-tale grime stains of annual rust-proofing treatments, be especially wary if it has a noticeably fresh-coat of black undercoating. A few spray cans of this can hide a million corrosion sins.

Don’t breathe any sigh of relief if the seller tells you the vehicle has been garaged every day of its life. Parking a snow-covered, ice and salt laden auto in a garage with interior temperatures above freezing during the winter will actually do more harm than leaving it outside in the freezing cold.

Salt can’t do much corrosion damage until it’s mixed with melted water, so a warm garage actually turns into a salty sauna for the poor car stored within.

Finally, if you’re thinking of buying something with a little rust with the intention of getting it fixed by your body shop, get an appraisal before making the purchase.

Your idea of a cost estimate and one from the pros can be very different.