100K? I dunno.. a local Ford cat told me not to leave them in that long... plus the closer you get to the 100K mark the chances increase of having problems removing them... truth.. yes?.. no?

 

No I read the thread on how to change them. That is not my question. My question is why are we changing plugs before 100K? and at what mileage should it be done.

 

The plugs "should" last for 100k, and they do last that long. The problem is they get carboned up at the sleeve and the longer you wait the more chance of the plugs breaking while taking them out costing you more dough or time for extraction or at the worst removing the heads.

 

What model spark plugs will my 07 have? The 1f plugs?

 

Stratus225, the plugs are typically good for at least 100k miles. I just had mine changed and had some big problems. After getting the new plugs in and ready to drive, the dealership told me to change them at 50k. This is after they told me to wait until I absolutely had to which ended up being 110k. They have clearly learned that the intervals should be less.

 

The plug you need is PZT1F

 

here's some good info:

http://www.angelfire.com/sd/vmkrampi...ug_change.html

 

Thanks for the link, but it is far the 5.4 2v engine in the 97-03 trucks.

Not the same process as the 5.4 3v in the 04+ trucks.

 

I just changed mine @ 37K and had no problems. I did have a decent amount of carbon on the plugs, I would not wait much longer than that based on what I saw on mine. By the way time is the key when soaking the plugs with the Kroil, I waited 3.5 hrs and still had some un-dissolved carbon but it was soft.