NGK Conventional vs. Ruthenium Plugs

[doitmyself]

Thanks for the responses. The jury is still out. Many still hang on to the notion that the OEM plug is a crucial design factor in a particular engine. Others like ka9mnx thinks there is a slight performance improvement in several ways. If anything, there should be an improvement regarding the huge electrode erosion that occurs on conventional plugs by 30,000 miles. Even then, many contend that modern engine computers compensate for that wear. Thanks again, except maybe Molakule who stirred the pot with his recent plug tip thesis, LOL.

 

[JeffKeryk]

Interesting... I have always been an OEM spark plug guy for most cars, especially Honda, Toyota and Chrysler...
I just changed the plugs on our old 1998 Accord LX 4 banger with 109K miles.
The OEM NGK copper plugs had probably about 32K on them.
The Honda Cap and Rotor and NGK wires had about 30K on them.
Plugs were worn but perfect.

I serviced the plugs (OEM NGK $12 for 4 from Amazon Prime), oil and atf. Car is perfect.
But if something like the Denso TT plugs @ $4 apiece would last twice as long, I would go that way.
Because over 30K miles the stockers were definitely running sub-par affecting expensive CA gasoline.

 

[UG_Passat]

Originally Posted by Skippy722
Originally Posted by spasm3
Originally Posted by jayjr1105

If it's a less expensive metal and it can withstand more heat, why not use them?



They are close, but the melting point of iridium( 4435F) is higher than ruthenium (4233f).

Why use ruthenium, if iridium has a higher melting point?

Iridium is $1400 and oz and ruthenium is $250 and oz. I'm sure the profit margin is much better if they can sell the ruthenium plugs at the iridium prices.

If the plugs are easy to get to and you don't mind changing them, sure use non- precious plugs every 30k. But if you have a difficult to change vehicle i'd use iridium, I don't get the advantage of ruthenium other than its a higher profit margin for the company.


MolaKule posted in another thread that ruthenium is more resistant to erosion. A spark plug also won't get anywhere near being that hot, so the slight difference won't mean much between the 2.

"The more exotic refractory metal tips simply give you more tip life and less gap growth because they erode less during the 'plasma' phase of the spark.

As of right now, Ruthenium seems to have the lowest erosion rate of all of the refractory metal center electrode tips.

Next year, another more exotic metal or metal compound may be found that surpasses Ruthenium.

"


What people forget to focus on also, is what's on the ground electrode end of the spark plug. It's not ruthenium, it's platinum attached to it, in both its ground electrode configuration (projected square electrode and the "twin tip" type).

Originally Posted by spasm3
Originally Posted by slacktide_bitog


Tungsten's melting point is over 10 thousand degrees, so why don't we have tungsten spark plugs?

Is ruthenium harder? Or does it have some other property that would make it last longer despite the lower melting point?


Do they last longer? Laser iridums are 100k.


But Irdium-IX is shorter. On my car, I have to replace them every 20,000 miles.

Laser iridium has a platinum wear disc on the ground electrode, which the Iridium-IX does not have.

 

[celicaxx]

I've always liked NGK V-Powers, mainly because they remind me a little of the "Splitfire" spark plugs they had back in the day.

By comparison, my least favorite plugs I've ever used have actually been Bosch. With Bosch platinums I had one friend's car misfire and have really hard starts, and switching to the cheapest Autolite coppers fixed it, as since the electrode length was covered by ceramic, once it wore down at all, it just had no more ability to fire. On my Sentra when I got it, I'm assuming my father put Bosch conventional plugs in it, and it straight up wouldn't start at all. As soon as I switched to a new set of NGK V-Powers, it fired right up. I do think the coil on my car was weak, as I did notice a big performance gain when I switched out my 25 year old OEM coil for a $10 ebay Chinese one, and I also noticed when testing for spark with the Bosches in it, the spark was more orange, not blue.

One thing a guy at Advance (actually knowledgeable guy who is great and does a lot of go fast car tuning...) told me when I told him my story was besides the whole "use what the manufacturer recommends" is that on older vehicles usually copper is actually superior, as platinum actually has higher resistance than copper. So if you have some other worn ignition components, the platinum's resistance may give worse performance. No idea on the resistance of iridium or ruthenium. But that makes sense in the context of my car. I think now on any older vehicle I'll probably go for copper plugs again, and likely NGK V-Power.

 

[Skippy722]

Originally Posted by celicaxx
I've always liked NGK V-Powers, mainly because they remind me a little of the "Splitfire" spark plugs they had back in the day.

By comparison, my least favorite plugs I've ever used have actually been Bosch. With Bosch platinums I had one friend's car misfire and have really hard starts, and switching to the cheapest Autolite coppers fixed it, as since the electrode length was covered by ceramic, once it wore down at all, it just had no more ability to fire. On my Sentra when I got it, I'm assuming my father put Bosch conventional plugs in it, and it straight up wouldn't start at all. As soon as I switched to a new set of NGK V-Powers, it fired right up. I do think the coil on my car was weak, as I did notice a big performance gain when I switched out my 25 year old OEM coil for a $10 ebay Chinese one, and I also noticed when testing for spark with the Bosches in it, the spark was more orange, not blue.

One thing a guy at Advance (actually knowledgeable guy who is great and does a lot of go fast car tuning...) told me when I told him my story was besides the whole "use what the manufacturer recommends" is that on older vehicles usually copper is actually superior, as platinum actually has higher resistance than copper. So if you have some other worn ignition components, the platinum's resistance may give worse performance. No idea on the resistance of iridium or ruthenium. But that makes sense in the context of my car. I think now on any older vehicle I'll probably go for copper plugs again, and likely NGK V-Power.


Pretty much all spark plugs use a copper core with an outer nickel alloy coating fused to it. Platinum, iridium, and ruthenium simply have a little puck of their metal welded to the nickel alloy covering the copper. "Copper" plugs stop at that nickel coating. But the difference in resistance is negligible, or should be to an engine with a decent ignition system, especially once you consider that most spark plugs also have a resistor that is 3,000 to 5,000 ohms.

Platinum is worse than nickel, but iridium is better... they're likely using alloys which can change these measurements from the pure metal (for better or worse), these numbers are for pure metals though.


Platinum:
Thermal conductivity: 71.6 W/(m·K)
Electrical resistivity: 105 nΩ·m (at 20 °C)

Nickel
Thermal conductivity: 90.9 W/(m·K)
Electrical resistivity: 69.3 nΩ·m (at 20 °C)

Iridium
Thermal conductivity: 147 W/(m·K)
Electrical resistivity: 47.1 nΩ·m (at 20 °C)

Copper
Thermal conductivity: 401 W/(m·K)
Electrical resistivity: 16.78 nΩ·m (at 20 °C)

 

[kschachn]

Thank you for the explanation on the resistances. It is a common misconception about the tip metals and what constitutes a "copper" plug.

 

[bulwnkl]

Maybe it's been covered already, but most of the ignition benefits come from the MUCH smaller electrode sizes (diameter(s)) at the firing point. These alloys simply _allow_ us to have those very fine tips that will last a long time.

 

[pbm]

I just put a set of NGK Iridium IX's in the 2009 Rav4 2.5 that my inlaw just bought with 165K.
The car had NGK G-Platinum's in it (which aren't factory plugs) so I know they were changed at least once before.
I also flushed it and replaced the coolant with PGL. The coolant that came out was pink so I'm assuming it was Toyota SLL but I noticed
a Gates hose so it may not have been the original coolant (or they could have just topped it up after the hose change).
The car seemed to have regular oil changes but the ATF looked black and dirty (although it shifted well and the fluid didn't smell burnt). I did one D&R using the Idemitsu TLS-LV (from the recent AZ 'Clearance' and the shifting feels great but the fluid turned dark right away so I'll do another
D&R this week....and maybe another in a few weeks with a new ATF filter (if I can get the pan bolts off....some of them look rusty and I don't want to break any of them off).
OK...back on topic....I used Rock Auto's recommendation that Iridium plugs "last up to 4X longer than copper plugs" thinking the Iridium IX's
would be a 100K plug....now I see they are really a 50K plug (if that)....I'm disappointed in that....I would have paid the extra shipping (different warehouse) and ordered Autolite Iridium's which have run great in every vehicle I've put them in and are a 100K plug (and are a bit cheaper too)....At least the 2.5 is a straight 4 cylinder and changing the plugs is a breeze....