I have a 2004 F150 Lariat with 90,000 miles. I have also worked on my vehicles for over 40 years. In my experience I have never had to replace spark plugs. Whenever I have pulled plugs, they've shown some sign of wear, but I just filed them flat, cleaned, regapped, and put them back in. Recently though I pulled the plugs on a Celica with 150,000 because the maintenance guide said to replace them about every 30,000 and it had been about 80,000 since we bought the car. Anyway, I bought new plugs, but when I pulled the old ones, they looked just like the new ones. This just reinforced my previous experience.

Now, considering that the F150 plugs often break off and you have to buy a special tool to get them out, I see no reason to replace them unless a plug problem develops.

Curious to see what you folks think about this.

 

I think that sounds like you dont care about spark plugs. They do more than make your engine run correctly, they make it run efficiently. Change your plugs.

 

I agree with the OP to a point. He stated he did pull, inspect, clean, and re-gap but he never said any thing about testing the plugs after this. Without testing how do you know the plug is not damaged/broken down internally? With the life of plugs extended as far as they are now I feel it would be almost as cost effective to replace with new, clean, inspect, and re-gap the old ones as spares in-case one of the new plugs is bad out of the box.

But this MHO

 

If he has the 5.4, you cant gap a SP515.........It cost the price of a tank of gas to replace every 100K. Its worth it to me to replace at the suggested intervals.

 

Never looked that close at those plugs (have now). In the case of the plugs designed like the SP515 I stand corrected, so I agree replace.

 

I'm sort of with you, if you're unsure then pull one and take a look before just throwing money at something. But really they're not that much money in the grand scheme of things so if you're at the interval I don't think twice about swapping them out.

 

Glad to get your feedback.

It has nothing to do with caring about spark plugs. Why do you say it makes it run more efficiently? I say it runs just as efficiently because so long as there is a gap, and the coil provides a strong charge, the fire between the gap will ignite the fuel and that's all that matters. And please don't tell me what to do. I resent people who tell others what to do.
I used to check them with a voltmeter; but that was years ago, before I decided I was wasting my time changing plugs that still were fine. And, I assume that if a plug is broken the engine will skip,it will be noticable, and I'll find a bad plug then. However, I've never had this happen.

It's not the money. It's more the principle. In my thinking I'm not replacing plugs that work fine. I'm waiting until there is a problem because over the years it's been my experience that spark plugs have not caused an engine performance problem. Also, for the F150, the high probability of breaking them, thus requiring the purchase of a special tool for extraction, just adds to my reluctance to change them.

Maybe I'm missing something though, like maybe there is evidence to support new plugs giving better gas mileage, or some other empirical benefit. But, all I've ever read is the manufacturer's recommending it after so many miles (which I've come to believe is a way for their service departments to make money) and lots of folks who just say you need to do it without any proof that it does any good. I think the latter are being duped, much like the folks what are getting their oil changed every 3,000 miles.

 

If I am going to go through the trouble of removing my plugs to inspect them .. They are getting replaced with fresh plugs..

 

Mine have been replaced at 100K then 150K I'll do them again at 200k A lot easier after the first time around.

 

Should not have problems after the first time.. That's why you have a re-designed plug now SP 515