 groove worn into it, it's time to change it. Or if you've got a lot of heavy buildup on them and they're fouling because of very short trips, like maybe you start it and you drive it a couple blocks and park it or start to move around the garage, they might be starting to foul where it's time to change it. But it's an 02. I mean, we're talking 20 years old, 23 years old. It's definitely not going to hurt to change them just for age. On the other hand, I have spark plugs in a Model T that were put in in 1975 that are still perfect.