I just bought my '05 SCREW last week with 125k on the clock. I've heard all about the issues with the factory spark plugs, and I've been debating putting in some high-grade spark plugs just because.

Being a used truck, I don't know the maintenance that has been done on the truck, and as such, I don't know when the spark plugs were changed on it (or if at all, TBH) let alone what they were changed out with. So I kind of have 2 questions in regard to this:

1) If the spark plugs were indeed replaced by 100k like they were supposed to be, is there any chance at all they were replaced with the same model spark plug, or did Ford learn their lesson and start using a different style for replacements? (i.e. if the original owner had the work done at the dealership's service dept, would they have used that same plug style)

2) If so, is there an easy way to check and see if it's the breakage-prone factory style spark plug without trying to remove one and possibly breaking it?

 

The original plug design made it possible for the plugs to snap in half when removed. The replacement plugs will not do that. You will have to remove one plug to see this.

 

The only way to check is to remove a plug. I did all mine in my 07 and didn't break any at over 100k miles. I got the motor up to operating temp and sprayed some Penetration Oil down all the cylinders. Let it soak for a while. Get it up to temp again and start loosening up the plugs. I would crack one loose, spray some oil, then move onto the next.

After that it was a "two turns out, one turn in" kind of process. Any time it started feeling bad, I sprayed more oil. Once They started moving well, I rattled them out with an impact.

The only plug that goes back should be the Motorcraft SP-515s. Don't waste time trying anything else.

 

On my 2008 5.4 I was all prepared with the Lisle tool and 8 of the SP-515s spark plugs. First one I pulled out was not an SP-515s 2 piece plug, it was one long threaded to the insulator. I found out it depends on if you have Build1(Black Boot) or Build 2(Green Boot). Before you buy all the parts, look under the hood at your coil packs to see which build you have. I only found this after pulling one plug and seeing it was about 3/8" shorter than the 515's and went on youtube and sure enough found a video on this about build1 or build2.

 

They went to the new one-piece plugs on late 07 builds. All the 08s and up should have them. his 2005 will have the two-piece unless someone already changed them out.