Iridium plug for V6

For those of you running iridium plugs, what model are you running and milage on them? Not looking to discuss iridium vs copper, lots of threads on that. I have about 60k miles on my

$54 NGK's 6619 Iridium Spark Plugs LFR6AIX-11-6 PCSNEW

NGK's 6619 LFR6AIX-11. I'll pull out a few soon to check how they are doing.

 

I've tried a few different plugs including OEM NGK replacements but my truck seems happiest with NGK Iridium IX Part #

$54 LFR6AIX-11 -6 PCSNEW

LFR6AIX-11. I Change them every 80k.

 

I went iridium at my first plug change. Truck seems happy and I don't have to do them as often, which reminds me.... when did I do them last? Driving to Moab on Sunday. Maybe I should do them before then. Shit.

 

Just jumping in this thread because i'm thinking of going to irridum from the standard copper. Iridium's come pre-gapped, dont they?

 

Always check the gap and adjust as needed. Go by the vehicle manufacturer's gap spec for that specific vehicle, not the plug manufacturer.

I've been running NGK Iridium IX plugs in my 4.0 for the last 9 years. The engine is dam near perfect. Smooth and responsive. But if I was buying plugs for it today, I'd go with Rutheniums. Those are even better IMO.

 

I remember from my days (like 18 years ago now) working at an autoparts store, they always told me not to gap the irridium plugs because it will damage the tip. Not sure if the information they got was true, but its something i've always kept in mind.

 

You can gap iridiums and rutheniums. You only need to avoid prying on the tiny electrodes. I recently installed new NGK Ruthenium plugs (similar to Iridium) in my old BMW. The plugs came gapped at .044 but BMW gap spec for that engine is .032. I was able to set the gap at the proper .032 and the new Rutheniums work flawlessly.

 

thank you, thats good to know information!

 

Here's a ruthenium spark plug experience:

I always used OEM plugs (90919-01263).
Changed the first at 60k-ish and I just changed them again at 112k about a month ago.

Decided to go for the NGK ruthenium because why not.

After a month of driving (600-ish miles) on the ruthenium, the truck is noticeably not as responsive and an average 1-ish mpg loss.

Back to OEM for me.

PM me if anyone wants the ruthenium plugs.

 

Me too. Been running these for about 10 years with absolutely no issues. My engine runs better than brand new. Very torquey.

 

I find that surprising. I went from NGK Iridium to NGK ruthenium in my other vehicle, a beemer. I thought the beemer had smoother acceleration with the rutheniums.

 

I found it surprising as well. Unpleasantly! I'm wondering if the three prong side electrode OEM might simply make a stronger spark than the one prong ruthenium. Aside from the metal that's the only difference.

 

I have Iridium plugs in my '11 offroad. 70k miles on the plugs so far. Runs well, still getting what amounts to "good" MPG. When the plugs have been in another 30,000 miles I will switch out.

 

Put them in my sisters 1GR 8 years ago, no issues yet.

 

Darn these threads, now I have to put another thing in my "add to cart". No idea when these plugs were changed, have 198k on my 2015 v6, but bought it last January. Been running great and getting the typical 20mpg, but maybe I need some???

 

The strength of the spark mainly comes from the coil pack, not the spark plug material. The electrode material mostly affects things like wear and long term consistency. There are some cool videos on YouTube that show side by side spark profiles with copper versus other materials, and you can really see the differences. I found this breakdown online I though was informative...

Copper (actually nickel-alloy tipped)
Excellent conductor, fires easily.
Runs cooler, great spark quality.
Wears out fastest (shortest life, usually 20k–30k miles).

Platinum
Harder than nickel, much longer life (up to 60k–100k miles).
Holds sharp edges longer → maintains good spark efficiency.
Slightly higher resistance than copper.

Iridium
Hardest and most durable (often 100k+ miles).
Can be made with extremely fine electrodes (~0.4mm) → needs less voltage to fire.
Consistently reliable spark, even under load and lean mixtures.

Silver (rare, mostly in racing)
Best conductor of all.
Very strong initial spark performance.
Wears out very quickly — not practical for daily use.

I’ve run both new OEM copper plugs and NGK iridiums, and my truck definitely feels smoother with the iridiums. I’m not exactly sure why, but I can tell the difference. Maybe it’s because the spark is more focused, instead of wandering around like it tends to on the larger copper electrode (those videos I mentioned really show this). It’s subtle, but you can feel it.

 

Just ordered a set from rockauto

 

I have denso iridium at 207k