04 Explorer 4.0 spark plug change interval

[GSP]

How many miles on factory plugs when changed and how did they look?

 

[E.B. Cornburner]

I changed mine at around 70,000 and they were pretty well cashed. The platinum tips were still intact, but the ground electrode was in pretty sad shape. If memory serves me correctly, Ford recommends 100,000 mile tune-up intervals under "normal" service, and 75,000 under "severe" service.

I went with the Autolite XP103 Iridium plugs...They weren't a whole lot more than the OEM installed double platinums, so I figured I'd give them a shot. So far, they're running great.