Spark Plugs - Looking for opinions

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Jun 8, 2016
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Texas, USA
Hey guys,
I always like to get your input on things like this, as point-of-view and experience can really help with decision making, since there are so many choices.

I normally stick to OEM parts when doing maintenance, but I also realize there can be quality differences if one is willing to step outside the OEM box.

Please share which spark plug you would recommend, and why. I'm not set on Motorcraft when it comes to spark plugs.

2017 Mustang 3.7.

Thanks!

Plugs.JPG
 
What is the factory plug Ir? You shouldn't need to change it - unless you just want to read it. Are you over 75K miles?

The new bosh finewire Ir seem well made, and the Autolite Ir have been use on Subaru with good results.
I would guess you have coil on plug ignition in that "Lincoln" V6 engine.

The usual advice is typically stay with factory part number on modern engines.
 
Iridium and Ruthenium with standard tip are the best for 'power' and economy especially under boost. I would use either of the NGK plugs. Not platinum I have seen these unable to supply spark on the dyno with boost. But, standard car should be fine with any.
 
In modern cars, the overwhelming line of thought when it comes to spark plugs is OEM or OEM or OEM. Not sure about Mustangs, but on Fusions, the OEM plug is an NGK. If you go to NGK's website and use their part selector, they'll tell you if they're the OEM. In this case, they say their laser iridium is "OE equivalent" so I think that means they are not the OEM in this case.
 
The car has 34,000 miles on it. Haven't touched anything yet, because the intake has to come off to get at the passenger side plugs. I'm assuming it has Motorcraft SP520s in it, but Ford does surprise me on occasion.

I do want to see what they look like, and I'm of the mindset that if I'm going to pull them, I might as well replace them with the best possible plug, and get anti-seize on them. Car runs fine.....this is just something I always do when I buy pre-owned.
 
What strikes me is there are several different gaps listed.
Make sure that is correct.
I honestly don't know why they put that on there. I gap all plugs to match my car's specs when they come out of the box, and they always come out of the box different from one another. The four Motorcrafts I put in my Focus last year....not one was gapped like the other.
 
I'm a big fan of the NGK Iridium IX, what I've used in Hondas with long service interval.

That said, different vehicle so I suppose default to the oem plug first choice. Close second choice would be NGKs, only because not oem.
 
Motorcraft or Autolite for Fords only. My friend put some NGK in his Ford and it fouled them out and ran terribly almost immediately, he put Motorcraft back in and problem went away. Some vehicles don’t like some plugs. Yes it was an old Ford but that’s happened to me plenty of times with other vehicles too.
 
I do want to see what they look like, and I'm of the mindset that if I'm going to pull them, I might as well replace them with the best possible plug, and get anti-seize on them. Car runs fine.....this is just something I always do when I buy pre-owned.
Slow down ... some, if not most, plugs need no anti-seize. Check the ones you finally end up with.

 
Some vehicles don’t like some plugs.
I learned this the hard way years ago. Back in the 90s, my parents had a Celebrity 2.8 V6. It needed plugs, and knowing that the back 3 plugs weren’t fun to change, I put Autolite Platinums in it hoping they would last longer. Started it up and it missed and sputtered at idle, but ran fine with the revs higher. After checking plug wires, etc, I finally replaced the new Autolites with a set of AC Delcos, and all was well. Ironic that by trying to save work in the future, I got to do the job twice.
 
Personally I would be less concerned about the brand and more concerned about the spark plug type. If it came with iridium plugs, stick with iridium. Toyota and Honda will often have a specific NGK and Denso plug as the OE plug, so they view both as equally well suited but they are always the same plug type.
 
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