Well reading this thread inspired me to check mine. I bought this Jeep a few years ago for my daughter and it came with a book of all the maintenance that has been done. Seemed very thorough, many pages but I never read all the details. I assumed it had platinum plugs and gas mileage around town was about 15.
So I started through the details yesterday. The freaking spark plugs have never been changed. 148,000 miles on the original plugs. The gaps were almost an 1/8". I can't believe the thing ran, let alone ran pretty well. Take a look!
I put the new plugs (exact same ones) back in, if they worked that well that long, no sense in changing.