FWIW, Motorcraft does not make spark plugs. For years they were made by Autolite and more recently by NGK and Denso as some one here mentioned. Even the plugs installed from the factory are not necessarily made by the same company as what Motorcraft sells as replacements and that is true for a lot of parts.
Gas mileage is down over the last few months and they’re dirty/oily with dark corrosion built up. Should have clarified: she runs perfectly compared to the NGKs. They can definitely use a change at 67k.
The part numbers are interchangeable. Specs are exactly the same between the two. Unless I’m missing something?
You are missing something, if you had the right plug, the engine would run like new.
The service manual already says to change the spark plugs at 60,000
Lol not a helpful reply. Thanks for the thoughtful input.
This is what I thought, it depends what dealer you ask. My local dealer said 100k. This is an ongoing debate due to misinformation from Ford. Which is why I suggested at least check at 60k ?
Sorry you didn't find it helpful. Frankly I am not surprised.
Oh, and they are not the same spec, they have a different heat range.
