[hampsterzone]

I changed mine at 90,000 miles. Actually twice now! I had to recently change them due to Auto lite plug failure. I was having all sorts of misses w/ no codes. So do yourself a favor and only use the exact Ford replacement. My mechanic used the special tool to remove my originals without any problems and mine was on a 2004 5.4 Triton. If I was you I would buy the parts from Ford and either do them yourself or have a mechanic to them. It cost me $130.00 plus parts. It is always better to do proper maintenance then costly repairs my friend! If you can afford it change the coil packs too and save the old ones for spares. You can do them yourself, pretty easy if you have the right tools to reach in the back. Good luck! Please do not go cheap, buy the more expensive Ford plugs. It ended up costing me a lot of money just to pull the Auto Zone plugs that were OEM replacements within 2 months.