Updated March 2019
Rotting metal doesn’t invoke thoughts of long-term reliability and dependability. But if you’ve found your dream car online, albeit with a few rust spots, should you really turn your back on it?
Rust happens when the metal in your car mixes with oxygen or water. It can be a serious problem and can spread like a rash.
“It can also be a real eye-sore,” said Craig Shuttleworth from Krown rust control. “But excessive rust often signals the impending death of a vehicle. Its useful life [is] essentially over.”
Types of Rust
Fortunately, it’s not all bad. Shuttleworth said that some spots are easily repairable and not much of a concern.
Some of these rust spots appear as little patches or bubbles on the paint surface of the car. Occasionally called “cosmetic rust,” there’s no doubt that it’s ugly but it’s also fairly localized.
Spots like this usually happen after a rock-chip penetrates the paint causing the exposed metal to react with water, air and other contaminants. While it weakens the paint around it, it’s not a big deal.
“This type of corrosion does not usually cause concern as it can be easily repaired with proper body preparation and re-painting,” reassures the expert at Krown. Usually, these small surface spots can be fixed quite easily and some people even manage to do it from the comfort of their own garage.
“Similarly, light surface rust on the underside of a vehicle also is also cosmetic and is not concerning,” Shuttleworth said.
On the whole, this isn’t too big of a headache. If you didn’t realize a rock-chip had affected your paint-job and left your car dirty for a while, then it’s feasible this kind of corrosion can happen. It will affect the resale value and appearance of the car if untreated.
It may take time and effort to fix some surface rust spots on the paint or body, but those kinds of rust spots aren’t necessarily a deal breaker. Fix it up nicely and the value of the car will rise again.
Un-Fixable Rust Spots
Rust in other places of the car’s body isn’t as easily dealt with. The list of problem areas is short, but serious.
“When corrosion is visible on the seams of body panels such as the inside bottom of the door, along the fenders or if there are any areas where the metal is completely rusted through then you should be worried,” Shuttleworth said.
Corrosion on thinner parts of the car may have even caused a hole in the body. This can mean significant problems in regards to safety – you don’t want to be inhaling fumes from your exhaust or putting other drivers at risk with body panels flapping or flaking about.
“If there are large areas of corrosion around the spot welds on the floor of the vehicle then you should be very worried as the vehicle’s safety has already been compromised,” he said.
These more serious looking problems are fixable but with a significant cost. Also, if you’re buying a car with an issue like this, likely it wouldn’t be able to pass a safety test without being patched up first.
Frame rust is a big concern, as it affects the integrity of the car. Bad enough frame rust can cause parts to snap off or crack, which will really compromise the safety of you, your passengers and other motorists. It may also significantly diminish the car’s ability to protect you in a crash. Other rusted components can lead to costly repairs.
“Other areas of concern are rusty brake lines and gas lines which can be expensive to replace,” Shuttleworth said. “If the car you are looking at has rusty front shock towers, this is also a clear indicator not to purchase the vehicle.”
How Bad Can It Be?
See Also: Should You Buy a Car With 200,000 Miles?
Not right away. “Take the time and properly inspect the vehicle you are thinking of purchasing,” Shuttleworth said. Determine the real damage. If it’s looking more like just simple surface rust, then you should call a mechanic to give the car a thorough look.
“If you do find a well-maintained vehicle, that has very little rust, keep it that way by protecting it with an aftermarket rust protection product,” he said. “This will help to protect your investment and will give you peace of mind that you have made a smart purchase.”