I very strongly suspect that when I bought my Mystique, with 109,320 miles on it, that the spark plugs had never been replaced ? that they are the plugs which it had right from the factory. I looked at the plugs shortly after I acquired the car, and they were noticably worn, but still in usable shape. As the car was running just fine, and I had more pressing matters to deal with, I left them alone. A few months ago, with about 140,000 miles on the car, it began pressing on my mind what the plugs had looked like when I inspected them a year earlier, and I decided that the time had come to change them. Still no sign of any drivability or performance issues related to the plugs, and no noticable difference when I put in new plugs, but here's one of the old ones:
It surely is a great tribute to the superiority of Ford's engines that my Zetec was able to run so well with the plugs in this condition.
