beatr911 .. The spark plug info I used was posted on the Focus Fanatics site. You can find the info here ..
The Duratec Sparkplug Sticky - Focus Fanatics. If, for some reason you can't bring up the post put this into the Search box .. The Duratec Sparkplug Sticky. A list will come up; click on the first item on the list. I went with the suggestions for economy and they seem to work.