How much rust is too much on a used car?
Spotting the difference between harmless surface wear and serious structural rot on parts like connector bars or jack points is incredibly difficult. This uncertainty leaves buyers panicking that their expensive investment will rot away in a few years, especially when conflicting advice from mechanic friends raises fears about hidden damage like previous welding.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Taking photos of the undercarriage and posting them to online mechanic forums for evaluationDid this help you?
- 2Trying to guess the severity based on how the rust looks on specific partsDid this help you?
- 3asking mechanics online to review a video of the undercarriageDid this help you?
- 4showing the vehicle to a friend who owns a garage for a second opinionDid this help you?
- 5planning to wire wheel the surface and apply a rust converterDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“I also thought it was bugger all rust to worry about but I showed it to my mate who owns a garage and he made me panic. Said he could see previous welding around a jack point but im not convinced”source ↗
“My main concern is the rust on that connector bar between the wheels.”source ↗
“Hi, I'm looking at buying this car but im worried it will rot away in a few years. It's massively expensive and im buying it as a bit of an investment so dont want it to rot.”source ↗
Where this came up
People with this problem also raised
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- 3Is rust underneath a car surface or structural?
- 7How to inspect a used car yourself without looking clueless