‘Built in Michigan but not made to stay’: Customer brings in 2021 Ford F-150 with 20K miles. Then the mechanic shows the real consequences of not washing your car regularly

A mechanic’s viral TikTok is sounding the alarm for drivers facing winter corrosion in snowy climates: Wash your undercarriage or pay the price.

NextGen Car Care (@nextgencarcare) shows us how winter corrosion happens when drivers skimp on an undercoat in areas with salty roads.

The video, which has been viewed more than 168,000 times, shows the underside of a 2021 Ford F-150 with 20,000 miles. The truck is showing excessive rust and winter corrosion from not having been properly protected from the elements.

“This is exactly why we’re supposed to wash them at least once a year and rust-proof them,” the narrator tells us. They then zoom in on deteriorated screws and joints at risk of developing leaks. “You can see this truck has no miles on it. It’s made to last a very long time, and it’s getting pretty nasty.”

Causes of winter corrosion

Even low-mileage vehicles can suffer significant winter corrosion if not properly maintained during winter months. The primary factors include road salt, moisture, and galvanic corrosion resulting from the interaction of dissimilar metals.​

In regions prone to snow and ice, transportation departments apply salt to roadways to enhance safety. While effective, these substances are highly corrosive to vehicle components. According to the U.S. Environmental Protection Agency (EPA), road salt can lead to environmental damage and accelerate winter corrosion.

A study by the American Automobile Association (AAA) made some shocking discoveries. In the past five years, 15 percent of drivers in winter climates had to get at least one auto repair for damage caused by salt and other de-icing chemicals. The average cost per repair was approximately $490. That led to an estimated total of $15.4 billion spent on rust-related repairs over that period.​

Explaining galvanic corrosion

The mechanic in the TikTok points to a more specific type of winter corrosion occurring on the transfer case, where steel bolts are used on aluminum parts. This creates a condition known as galvanic corrosion, which happens when two dissimilar metals come into contact in the presence of an electrolyte—like salty water. In this case, the aluminum acts as the anode and corrodes more quickly.

Since aluminum is less noble than steel on the galvanic series, it deteriorates first. It happens especially in winter climates where road salt acts as the electrolyte.

The 2015 redesign of the Ford F-150 introduced a lightweight, military-grade aluminum alloy body to improve fuel efficiency and payload. Aluminum doesn’t rust like steel but is highly susceptible to corrosion, particularly galvanic corrosion, when it comes into contact with steel or iron.

Is undercoating worth it?

Undercoating has long been marketed as a key preventative step to protect your vehicle’s frame and undercarriage. But for lots of potential buyers, it seems like an unnecessary add-on that dealerships use to try to tack a little more onto the sale price. Is it really necessary—especially on newer trucks like the Ford F-150?

Pros of undercoating

• Prevents rust and corrosion: By adding a protective layer over metal surfaces, undercoating shields against salt, slush, and moisture that accelerate corrosion. This is especially valuable in places with harsh winters or coastal environments.
  
• Extends vehicle lifespan: Preventing rust can help preserve the structural integrity of a vehicle over time, especially in areas like the frame, brake lines, and suspension components, which are critical for safety.
  
• Adds resale value: Some buyers may see undercoated vehicles as better maintained, particularly in rust-prone states.

Cons of undercoating

• Cost: Professional undercoating can cost anywhere from $150 to $1,200, depending on the type and whether it’s done at the dealership or an aftermarket shop.
  
• Not always necessary: Modern vehicles come with factory-applied corrosion protection, including galvanized steel and factory coatings. In areas with minimal salt use, undercoating may be redundant.
  
• Requires maintenance: Undercoating can wear off or trap moisture if not properly maintained, potentially causing more harm than good.

@nextgencarcare Low miles, but high corrosion. Get an underbody wash + rust proof to prevent this! #rust #corrosion #underbodywash #protection #lowmiles #truck #mechanic #technician #fyp ♬ original sound – NextGen CarCare

Car washes pay off, too

Experts also recommend washing your vehicle at least every 10–14 days during winter months. A car wash is also needed after any major snowstorm when salt is heavily applied. If possible, wash your vehicle during the daytime when temperatures are above freezing and the vehicle can dry fully afterward. Automatic car washes with undercarriage sprayers are particularly useful.

We’ve written before about how the winter months are some of the most profitable for car wash businesses. Employes also offered tips and secrets for how to avoid issues with maintenance.

Commenters on the clip had plenty of thoughts and advice for winter car care.

“I spray a salt water solution on mine twice a month it builds up an immunity to the salt,” said one, joking about the effectiveness of vaccines.

“With the price of them they should come rust proof,” said another price-conscious motorist.

And there was one who cautioned against the desire for low-mileage vehicles. “Low miles usually means more rust and corrosion unless it’s garage kept,” they wrote.

The Daily Dot reached out to NextGen Car Care via a comment on the clip and to Ford via email.

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