Rod, They wear out normally, but fast. I don’t let them get to the point that they can break. They start clunking around, and you can see movement when you test it. Then it’s a matter of checking them regularly enough until they definitely need changing. I’ve had to replaced the original ball joints/control arms under warranty (nylon, no zerks), and then had just the ball joints replaced one at a time by other mechanics out of warranty (these ones took grease). Earlier this year I changed out both control arms again at home - these came with nylon ball joints again. Multiple parts stores, mechanics, etc. have said to me that these cars kill ball joints.