Pulled the boots and cop off the 07 f150 5.4 i just bought with 88000 miles on it and on tip of spark plug where the cop conects to the plug is red like someone marked it with a red permenent marker. does anyone know what this means? does it mean they are the factory plugs? or maybey the truck had spark plugs changed at dealer with the antisieze and this is there way of telling? Also anyone know a good place to get my plugs changed in eastern nc im stationed in goldsboro but dont mind driving a hour or two. thanks

 

I think it's a factory plug marking.

 

Yeah, factory plugs have paint marks on them showing that they are factory installed

 

That what I was thinking. When I had mine changed after I bought the truck I thought they told me that. And the new ones they put in were marked with a blue tip. I guess to show they were changed at a ford dealership.