I recently noticed a drop in gas mileage at 78K miles so I figured it was a good time to change the spark plugs. When I went to the parts store, I told them it was a 2008 4wd 4.6 and picked up the platinum plugs at $80. When I went home to change them and pulled the first plug, it didn't match the platinums. I tood the plugs back to the store and they matched up the OEM plugs to a non platinum set for $36. While I'm happy it was cheaper, I'm confused as to why they didn't show these plugs as OEM for my truck and why my truck doesn't have platinum plugs?

Any ideas? by the way, yes I did try to search this and other threads for the answer before I posted.

By the way, the old plugs looked good and the process was simple and event free! didn't take 2 hours.

Thanks,

 

The OEM plugs in a 08 4.6 are Motorcraft SP-493. They are in fact single platinum and are $2.47 each at rockauto.com, $3.49 at Autozone and O'Reilly.

 

Yes the SP-493 is what I have but Autozone showed a 507 or 509 for that model. Was that just a mistake then? I have the same 4.6 as the other 2008's out there. Guess I'm not special after all.

 

The 507's and 509's are for the 5.4 3 valve. Completely different head designs.