Man Said a Marking on a Mazda's Coolant Tank Led Him To Walk Away From a DealGuessing HeadlightsHenry KelsallThu, September 17, 2026 at 12:30 PM UTCAdd us on GoogleImage Credit: MazdaA man and car enthusiast has taken to TikTok to say that he walked away from buying a Mazda after he spotted a marking on its coolant tank. Car enthusiast Ty Backes (@tybackes) was the one who had been looking to buy the Mazda.The video showed that paying close attention to small details can sometimes save you from being stuck with a lemon of a car. In his video, Backes noted a small marker line made on the plastic receptacle that held the coolant in the car.According to Backes, if you are buying a used car, pop the hood and see that kind of mark on the coolant and that the coolant is below the mark, you should walk away. No questions, just shut the hood and walk away from the car. That was the TikTok user's advice.AdvertisementAdvertisementA look through the comments showed that quite a few people were confused by this. "What does that mark mean?" asked one of them. However, others were able to work out what the mark meant and why you should avoid buying a car if you spot it with this mark.What the Coolant Tank Mark Means"When you pop the hood and check the coolant. And there's a mark, and the coolant is below the mark, just shut the hood and walk away," said Backes in his video. One commenter seemed to pick up quite quickly what it was that Backes was referring to. "It means there is a leak somewhere that they know about. They marked it after filling it, and it leaked out," they said.The mark is where the coolant was filled up to, because they suspected a leak. If an engine doesn't have coolant in it, then it is going to get very hot, very quickly. Others who watched the video also said it could be a sign of deeper problems, and backed up Backes's claim that you should always check for the smaller details on a used car."The advice here is to pay attention and look for clues. If there is no external leak and they are monitoring the coolant levels, that means it's probably a head gasket," said the TikTok user. Equally, while the line doesn't mean the issue was specifically what Backes said, it is an indicator that the previous owner was watching their coolant levels and was worried about what they were seeing. But others also said that it might not have been that big of a deal.The Coolant Issue Might Not Have Been Too SeriousOne person argued that the marker could have indicated that the fluid level in the Mazda was fluctuating depending on the temperature in the engine bay. Thermal expansion can cause coolant levels to appear higher when the engine is hot, versus when it is cooler. When it is cooler, the coolant level can look like it is lower. Potentially, the previous owner of this Mazda had simply overfilled the coolant tank, causing it to spill over when they were driving it.AdvertisementAdvertisementWhatever the case, checking on the coolant level of your car is still a good idea. It is an easy thing to do and is inexpensive, and if the coolant level is too low but you catch it, you can get it topped up or even have it checked for problems if you suspect something is wrong. Think of this video as providing some good guidance regarding checking coolant levels. In an ideal world, the worst-case scenario is that, if you suspect there is a problem, you just need to take your car to a garage or mechanic. It is always better to be safe than sorry.If you want more stories like this, follow Guessing Headlights on Yahoo so you don't miss what's coming next.
