I want to change plugs (and probably wires) in my fiancee's 2004 focus sedan. I know I can request the motorcraft SP-463 plugs from advance, but they have a number of platinum plugs in stock. It sounds like these plugs are supposed to last longer. This is a normal daily driver, and she doesn't care too much about increased performance.
I want to know what I'm looking at as far as plug longevity. Sounds like the copper plugs need to get changed more often. What kind of difference in length between plug changes are we looking at between copper, platinum, iridium, and plugs like the E3 diamond fire plugs? If its a lot, it seems like longer lasting plugs would be a better investment, but I just don't know too much about this. If someone could help, that would be great.