 I'd take the plugs out and look at them. And it used to be that if the plugs came out, you just change them. But at, let's say, $10 or so, $10, $12 a plug, there's really no reason to change it if the plug is not worn. And you'll see the wear on it. If that electrode on there has got a 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.