ive only done three three valve motors so far and knock on wood havent had one problem yet. Maybe im pushing my luck on the side cash................

 

why bother changing the plugs if the truck runs fine.

If, and it is doubtful, you gained 1 MPG fuel economy by chaning the plugs, how many tens of thousands of miles would you have to drive to realize the return on spending 600 to 1000 bucks. 600 to 1000 bucks could buy a lot of gas.

if it starts easy and runs fine, drive on.

 

i do it because 100k intervals is ridiculous! Did my 2004 F350 at 50K just because and the plugs were showing signs of wear already, my girlfriends 2008 Pontiac G6 GT that she bought brand new only has 60xxxx and just last week threw miss fire codes, did COP swaps etc nothing so i decided to swap the 100K plugs they were SHOT! Tips were nearly gone gapped and installed new plugs with original COP's no more misfire or codes. Changed plugs on other vehicles under 100K and same thing plugs all show signs of wear and out of gap, seems smart to do maintenance before you have more problems down the road to me personally that is

 

No it's not for the overwhelming majority of vehicles out there. There are lots of cars and trucks that run just fine on plugs with 100,000 miles. My mom's car was one of them, there was absolutely no change in how the car drove after the plug change. Fuel economy didn't change either.

Some folks like to replace parts early because they concoct silly reasons why the factory recommendations aren't good enough. Of course none of them are engineers though. The same group of folks generally insist on 3,000 mile oil changes regardless of what data suggests.

 

I will agree with the first part, under certain circumstances. I changed the plugs in my Bronco at 185k miles and it still had the factory plugs in it. No issues at all. I don't mind doing that in a cast iron head. I replaced the plugs in my sd at 45k because I had two coils and two plugs go bad and I wanted to make sure they were all installed correctly. I have several cousins, aunts and uncles that work in the Chevy plant in Moraine, Ohio and only one of them is capable of changing their own oil or tire, so I sure don't trust the assemblers to put plugs in an aluminum head.

I may not be an engineer, but that doesn't mean that those who are know everything and are correct 100% of the time. A lot of those engineers have never turned a wrench on a car and if they had they wouldn't design some of the stuff they do(6.0, 4 thread head modulars, 2 piece spark plugs, etc). I don't do a 3,000 mile oil change, but I do change mine every 5,000. It costs $20 to do a uoa and you still have to crawl under the vehicle and drain oil. For $30 I crawl under my truck, drain oil and know that my oil and filter are good. If it costs the same and involves the same effort I would rather have new product. That doesn't make someone "silly," it just means they maintain their vehicle differently than you do yours. They could say you're silly for spending the same as them and running oil/filter that is twice as old as theirs. As long as the vehicle is maintained, that is all that matters

 

"What was the build date of your truck? If it's in 2008 you have a good chance of having the updated one-piece plug design that doesn't come apart. If that's the case your plug change will only take a little over an hour. Easy stuff."

My truck was built in May '08. It has 143K and the original plugs. Are mine one-piece?

 

Most likely yes. I believe the change occurred either the beginning or end of November 2007 at the engine plant.

 

My door sticker says 12/07. Is that my build date?

 

Yes, and you most likely have the old design two-piece plug that can break off.

 

These horror stories make me love my '03 F250 2v 5.4L even more. Took my less than an hour to change all 8 plugs at about $3 each. Changed them at 65k miles. Leaving plugs in for 100k, even though they may be rated for it, just seems not so smart to me.

 

So I have heard the boots are brown or black? Brown has the 2 piece plug?

 

Really using mileage is a crappy way to tell when maint should be done, engine hours is far better. I have experienced rougher idle at startup, misses and more than normal detonation on modulars at as little as 50k. A plug changed fixed it. However those engines have higher hours for the miles.

As for the 3V plug design, talk about an idiot that designed those. If they would have designed the plug right and machined the lower portion of the plug out of one piece it would have been much better and lead to much less breakage issues. But welding the plug body together coupled with the much longer than need be body and they stick and break. For got it right later in 08' (probably copied the plugs Dodge was using in the hemi) and then axed the engines in a couple years anyway. Bravo.

 

If I remember right the Black boot is the older design and the Brown boot is the newer design.

New design plug on top.

 

Ok, thanks guys. I will just have to suck it up for the first change. I bought the truck used. Don't know if they were ever changed. Bought the truck with 80k on it.

Shot

 

I run Marvel Mystery oil in every tank of fuel. Don't know if it helps. Does not seem to hurt anything. DKF, I like your by line.