Platinums vs Iridium spark plugs, I dont get it

[Corvette Owner]

I replaced iridium plugs in my daughter's Chevy Malibu after 110,000 miles and they looked like new.

I will be using iridium plugs in all my cars.

BTW, Chevy changed the Corvette's plugs to iridium years ago.

 

[mechtech2]

Originally Posted By: cutter
Originally Posted By: Carnoobie
Originally Posted By: Drew99GT
Durability mostly, and iridium costs more. That and the tip of the center electrode can be made very small because of the durability of iridium, which supposedly enhances spark quality.


Then how does Iridiums compare to double platinums? I was told single plats will last 50k and double 100k to match Iridiums


Platinum isn't as good as a conductor as iridium.

So it goes

Performace:
1. Copper
2. Iridium
3. Platinum


Longevity:
1. Iridium
2. Platinum
3. Copper


You left out common steel, which is superb when new and sharp.
Where are you getting copper tipped spark plugs, BTW?
It usually is in the core, and does not wear. Some tips are copper/nickel alloy.

 

[Carnoobie]

Well i feel now that i could have just saved the $35 and got single platinums but too late now. if single plats go 100k KM then i should have just done that.

 

[Trav]

Quote:
So it goes

Performace:
1. Copper
2. Iridium
3. Platinum


Longevity:
1. Iridium
2. Platinum
3. Copper


Not really. Iridiums and Platinums use a copper core anyway.
As Steve pointed out some ignition systems need different materials.
Waste spark systems (DIS & EDIS) need double noble metal electrodes for longevity.
The finer the electrode the shorter the lifespan but is less demanding on the ignition system as long as the gap holds within specs.

A very fine wire Iridium 0.4mm wont live anywhere near as long as an 0.6-0.7mm fine wire.
A double platinum will outlive all of them especially in a waste spark system.

Generally.

Performance:
Iridium (Very fine 0.4mm)
Platinum
Copper

Longevity:
Double Platinum
Platinum single (about the same as a Iridium).
Iridium (fine wire only not very fine)
Copper and very fine Iridium are about the same.

 

[JOD]

Originally Posted By: Trav


Longevity:
Double Platinum
Platinum single (about the same as a Iridium).
Iridium (fine wire only not very fine)
Copper and very fine Iridium are about the same.




That definitely hasn't been my experience. I'm sure you see a lot more spark plugs than I do, but I've seen 4 sets of NGK Lasers (the bigger-tipped OEM plugs) with mileage of 50-100K, and there was almost no increase in gap. In my own car, the stock platinums were well out of spec @ 72K. I just looked at one of the front Lasers (the replacements), and there's no wear that I can tell with my old/cheap spark plug gauge.

No question that there's a difference between Iridium plugs, in terms of both performance and durability, but the NGK Lasers (a dual Iridium plug) seem to be about the longest-lasting plug out there, and they're certainly out-performing the OEM double platinums. Given that I have one of those "have to remove the engine to get to the back plugs" cars, this is a pretty big deal for me. Otherwise, I really don't think they're worth the cost.

 

[Trav]

Quote:
NGK Lasers (a dual Iridium plug) seem to be about the longest-lasting plug out there

Yes those and there are a few hybrids on the market that may last longer than double platinum.

I dont see many of them that have been in service a long time. The autolite hybrid iridium/platinums are readily available but are not US or Japan made so i dont even consider them.

 

[DBMaster]

NGK Laser Iridium is an iridium/platinum plug. The disc on the ground electrode is platinum. That is what is OEM on my car and what you are supposed to use to replace them.

 

[SteveSRT8]

Originally Posted By: Trav
Quote:
NGK Lasers (a dual Iridium plug) seem to be about the longest-lasting plug out there

Yes those and there are a few hybrids on the market that may last longer than double platinum.

I dont see many of them that have been in service a long time. The autolite hybrid iridium/platinums are readily available but are not US or Japan made so i dont even consider them.


The 6.1 community has a great deal of experience with NGK iridium/plat hybrids as they have been factory OEM since 05.

The spec calls for 100k miles replacement, and they actually last MUCH longer in almost anything.

I don't usually find myself in disagreement with Trav, but on these we are far apart! One of the LONGEST lasting plugs I have used, and OEM in many of our fleet trucks.

 

[Trav]

Quote:
but on these we are far apart

Steve i wrote it wrong. I agreed with JOD that there ar longer lasting lasting plugs then the double platinum.
I just do have many cars come my way that have them installed so i cant say just how long they can go.
I have heard of some of these things going well beyond 100K.

I did a bad job of mental German to written English translation on that one.lol

 

[GMBoy]

Originally Posted By: SteveSRT8
First, note that ALL PLUGS are copper core. The only part changing is the electrodes.

.


Good to point this critical fact out. I think the only exception to this rule are Bosch Platinums. IIRC, They advertise 99.99% pure platinum electrode and core.

 

[Trav]

I think Bosch is playing word games.
Maybe the core at the firing tip, if the whole core from the wire terminal through the insulator to tip were platinum it would be a huge $$$$ plug.

 

[DBMaster]

If the plugs last 100K+ miles I wonder why Mazda specifies a replacement interval of 75K for my car. It's not like 12:1 is outrageous compression.

 

[Oregoonian]

Recently replaced the plugs on my 03' Focus....at 104K miles. Removed the original double platinum plugs, and they looked liked they could have gone another 30K.

Replaced them with Autolite APP 103 Double Plats....which I paid under $3 each (after rebate). My vehicle runs smoothly, without any issues. Should be good for another 100K.

 

[dparm]

Originally Posted By: OrdnanceMarine
Originally Posted By: Drew99GT
Durability mostly, and iridium costs more. That and the tip of the center electrode can be made very small because of the durability of iridium, which supposedly enhances spark quality.


+1

Platinum is really only good from a durability standpoint but iridium allows for a much finer electrode tip which gives a more consistent spark and creates a smaller "shadow" as the flame front propogates away from the spark.



Correct. That's how Denso is able to get the ultra-sharp 0.4mm tip and yet not need replacement every 5k.

 

[mechtech2]

Car spark plugs are resistor type.
So who cares what the core is? It is modulated anyways.
The heat range is also controlled by many factors.
Once again, who cares how they do it?

Tips?
Plain steel rocks the house. However, NOT long lasting at it's peak. A silly short life in today's cars.
Precious metals last a long time. Double tips are invaluable for waste spark ignitions.
Iridium or Platinum?
For me. Plats are so good, why go out of my way for theoretical or potentially better iridiums?

Heat range is #1. As cool as possible, and still being able to keep clean in all conditions. Extended insulator tips [almost universal] are great for wide heat ranges.

BTW, not only do I gap precious metal tipped plugs, but also back file the steel side electrode for better gas in/out, AND often dress/file old Plat tips as well! They do wear and get rounded.

 

[HTSS_TR]

Originally Posted By: mechtech2
Car spark plugs are resistor type.
So who cares what the core is? It is modulated anyways.
The heat range is also controlled by many factors.
Once again, who cares how they do it?

Tips?
Plain steel rocks the house. However, NOT long lasting at it's peak. A silly short life in today's cars.
Precious metals last a long time. Double tips are invaluable for waste spark ignitions.
Iridium or Platinum?
For me. Plats are so good, why go out of my way for theoretical or potentially better iridium?

Heat range is #1. As cool as possible, and still being able to keep clean in all conditions. Extended insulator tips [almost universal] are great for wide heat ranges.

BTW, not only do I gap precious metal tipped plugs, but also back file the steel side electrode for better gas in/out, AND often dress/file old Plat tips as well! They do wear and get rounded.

Platinum plugs are OEM for my cars, from LS400 to Honda S2000.

Why Honda uses Platinum plugs in the 9,000 RPM engines ? If Iridium is better than Platinum then Honda would use it, after all the cost is only $8-10 more for 4 plugs.

 

[GMBoy]

Originally Posted By: Trav
I think Bosch is playing word games.
Maybe the core at the firing tip, if the whole core from the wire terminal through the insulator to tip were platinum it would be a huge $$$$ plug.


They may be, but they clearly state:

"Bosch Platinum Plus spark plugs feature a pure platinum centre electrode that’s heat-fused into an extended ceramic insulator to eliminate air gaps which exist in platinum alloy tipped plug"

This same language is mentioned on the basic Platinum plug too and I remember seeing a cut-away pic of a plug on a box that showed the entire center eletrode being of platinum.

Here is there catalog of plugs:

http://www.bosch.com.au/content/language1/downloads/A_Sect_Spark.pdf

 

[GC4lunch]

Originally Posted By: DBMaster
If the plugs last 100K+ miles I wonder why Mazda specifies a replacement interval of 75K for my car. It's not like 12:1 is outrageous compression.

Habit. Mazda specifies the same replacement interval for the 3.0 liter V6 engine in the Mazda6, and that has a much lower compression ratio than your SkyActiv Mazda.

The OEM plug in the Mazda6 V6's Ford Duratec engine is a double platinum fine wire, and the owner's manual says to replace it at 75,000 miles with a Motorcraft AGSF 22FCSM, a part number no longer recognized in the Motorcraft catalogue. We have the original plugs in ours at 85,000 miles, and plan to replace the plugs at our next oil/filter change at about 90,000 miles. Our choices are the NGK ITR5F13 (NGK 6044), an iridium/platinum plug with a 0.6 mm iridium center electrode, and if we install those, they should last until our car hits 200,000 miles or until I am pushing up daisies, whichever comes first; or we can install the Denso IT16 (Denso 5325) with a 0.4 mm iridium center electrode, which will give slightly better power and slightly better fuel economy, but which probably would need to be replaced -- due to wear on the center electrode -- in the 110,000 mile range on our car's odometer. Is the Denso's extra performance worth getting only one-quarter the service life of the NGK?

Eye-opener about the effect of a 0.4 mm center electrode

 

[HTSS_TR]

The price of Platinum is about $1600 an ounce. If the whole core is platinum, each plug would costs more than $100 retail.

 

[SteveSRT8]

Originally Posted By: DBMaster
If the plugs last 100K+ miles I wonder why Mazda specifies a replacement interval of 75K for my car. It's not like 12:1 is outrageous compression.


You may have a multi-strike ignition system. I know merc is using them on one of their V6 gas engines.

Regardless of specified interval I have run them WAY out beyond it. The newer cars set a misfire code very easily so you'll know!