So you take your car to your mechanic for an oil change. Someone meets you in the waiting room, a somber look on their face. They tell you that you also need to replace your tires, turn signal bulb, and windshield wipers. You know how to inspect your tires and turn signals yourself. But how do you actually know when your windshield wipers go bad?

TikToker Billy Rubino shared this handy life hack with his followers [embedded below]. It’s a quick and simple way to tell if your windshield wipers are still good or need replacement.

He said, “Maybe a lot of people know this, maybe a lot of people don’t. But, in case you don’t, you’ll see this dot right here on your windshield wipers.” Then he lifted his windshield wipers off his windshield and showed a small black dot on the metal frame underneath.

“If you ever see this turned yellow, that means it’s time to replace it.”

When do your windshield wipers actually need replacing

The truth is not every windshield wiper brand has the same feature. But many of them have a wear indicator built into the frame of the wipers. It is a circle that is either black or green. It is engineered to measure how far the rubber in the blades has degraded. When the rubber goes brittle and no longer does a good job wiping water off your windshield, the dot should change to yellow.

I’ll add that sometimes windshield wipers need replacing before this indicator turns yellow. But this is usually due to an obvious tear or other problem with the rubber wiper blade that leaves large wet spots on your windshield.

Note that some wiper brands also have thin strips of rubber engineered to be torn off every season, leaving a layer of fresh rubber that’s ready to go. This is a procedure you should do long before your wear indicator turns yellow.

MotorBiscuit has reached out to Billy Rubino (@billyrubino22.4) on TikTok for comment. You can watch his video embedded below: