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When Is the Best Time to Undercoat Your Car

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Spring – not fall – is the best time for rustproofing

Fluctuating temperatures and a season of grime make the possibility of rust more likely than ever

Mar 10, 2017 • November 13, 2020 • 4 minute read • Join the conversation
Road salt and grime will collect under your car during the winter.
Road salt and grime will collect under your car during the winter.

Right now is the perfect time to rustproof your car.

If you're beating yourself up a little because you never got around to rustproofing last fall, fear not. There is a mulligan that is actually a better option than your first choice.

Now is a great time of year to begin, or maintain, the rustproofing option. While there are several ways to go about the process, I prefer an annual drip oil application. There is also undercoating, which essentially seals the undercarriage of your car with a substance that hardens as it bonds, but it can crack and let moisture in, and then that hard seal begins to work against you, by trapping that moisture and encouraging corrosion.

You can buy those electronic boxes they push on you when you purchase a new car, but I hope you didn't. They're expensive ($750 and up, depending on what they get you for), based on totally flawed science, and they don't work. "They're supposed to be a sacrificial anode made of zinc, to attract corrosion. I've seen rust on the fenders and struts they're attached to, as well as the actual bolts and brackets used, and the wires leading to them. They don't work," says mechanic and Centennial college professor Chris Muir.

  1. Rust never sleeps: Here's how you can protect your car

    Rust never sleeps: Here's how you can protect your car

  2. Spring inspections can save money down the road

    Spring inspections can save money down the road

There are still a handful of places that will do an old school grease coating, but generally speaking, in today's marketplace, we're talking about undercoating and drip oil processes. When you bought your car, you were probably offered this extra, and depending on what your choice was at that time, it is still something you have to give a think to about once a year if you want to maintain the upkeep of your car, especially if you plan on keeping it for the long haul.

If you elected to buy the undercoating or rustproofing option through your dealer, your warranty paperwork will specify they have to inspect it once a year. It is vital that you do this to avoid invalidating your warranty. Do your annual inspections and keep excellent notes.

Many cars have noted rust spots, places where corrosion is a bugaboo. It is essential that if your vehicle has any of these known vulnerabilities that you address it before, not after, the rust sets in.

But if you recently purchased a new car and haven't gotten around to it yet – like me –  and thought you'd do it in the fall – like me – and didn't – again, like me – what should you do?

"People don't realize that now is a crucial time in the development of corrosion," says Freeman Young, president of Krown Rust Control. (Krown Rust sponsors a TV show I host, but I'd been a customer long before I heard of Freeman Young.) "This time of year, we see temperature spikes, and it's those freeze-thaw cycles that pushes moisture and humidity into places corrosion starts."

Muir concurs. "It's like condensation on a bathroom mirror. You've got cold steel that gets hit with a rush of heat and humidity from the ground, and it creeps into crannies and between panels really well."

We also use increasingly complex chemical formulations to salt our roads . The magnesium chloride now in common use is very sticky; the idea is it will stick to the road better, requiring fewer applications, and be more effective beneath anticipated precipitation. The problem? That sticky nature also sends it up into the underside of your vehicle, where it also sticks with a newfound tenacity.

Rust prevention isn't just about the body panels and seams. Brake lines, electronic connections, sensors, every point where there is a weld or one type of material meets another is susceptible to corrosion. An annual application of a product that bonds to all of those surfaces, and is also sprayed into very specific points inside your car's frame and body, is my choice, though Young stresses if you're happy with the service you're getting from your rust prevention provider to stick with them.

If you're worried that you just let your new car go through a winter of salt and brine unprotected, don't be. The product is applied with a high pressure that displaces the moisture and crud. The light oil they use (it's an amber colour) will drip a little afterwards (hence the name) but it's environmentally friendly and is actually the delivery system for the rust inhibitor. Your protection isn't leaking or washing away.

New cars come with rust guarantees, and if you're leasing a car I wouldn't bother getting it rustproofed. But if you're planning on keeping your car for years and want to keep it corrosion free, now is a perfect time of year to start the process.

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When Is the Best Time to Undercoat Your Car

Source: https://driving.ca/auto-news/news/spring-not-fall-is-the-best-time-for-rustproofing