Obsessive about oil, filter, trans fluid and filter and fuel filter changes but somehow lost track of plug change intervals. Pulled the original plugs out at 80K and they were all the same nice light tan. I don't know what these motorcraft center electrodes look like new but they looked like the sharp end of a pen now. All gaps were at spec. I used plain old Autolite AP104's and the car seems to idle a little smoother, or maybe it's my imagination. This has to be the easiest car on the planet to change plugs (and oil and filter) on.