Iridium vs Ruthenium spark plugs

[Deontologist]

I have a 2012 Lexus IS350. OE plugs are Denso long life iridium's that have a triple ground configuration. Manual says to change every 60k miles. I did mine at 100k and the idle immediately changed from noticably rough through the steering wheel to butter smooth with the fresh NGK Rutheniums. Fuel economy got a healthy 1 to 2 mpg bump even with more aggressive driving.

I got about 15k on the plugs now. No issues. The Rutheniums are supposed to be harder and therefore more durable than Iridium's. I guess we'll see closer to 60k. Maybe these will be able to last longer than 60k because Ruthenium is harder than Iridium??

 

[UG_Passat]

Now that NGK specs the Ruthenium HX PSPE #92400 in the correct gap for my car... I ordered them a while back and installed them.

I have had the NGK Iridium IX, and after 20,000 miles, the mpg always got bad. Maybe these will last the factory interval of 60,000 miles.

 

[willbur]

Originally Posted by slacktide_bitog
They know you'll have to pull the head anyway to do the head gaskets

See that's the internet blowing things out of proportion as to how bad an issue really was... I've owned 6 Subarus (two currently) with somewhere around 500k total mileage under my use, and never had any issues with the HGs. One of them (Tribeca) was a 3.6 so not affected, but the other 5 were all the supposedly prone years: 2001, 2004, 2005, 2007, 2009. I have no qualms buying another EJ25 since between the SCC and the revised MLS gaskets put into circulation since somewhere in the 2007-2008 range have shown a majority of maintained engines have little issue. Sure, there was a campaign to fix the HGs which probably was needed due to a faulty initial design, but plenty have lived long happy lives.

The problems really seem to crop up on cars that have neglected cooling systems (spent coolant) and/or don't use SCC when the coolant is changed.

Yep- internet hysteria. One guy posts an opinion, 10000 internet experts repost it and now its a huge "issue". Happens a lot and clever parts purveyors exploit with "fixes" for non existent problem.

 

[GMBoy]

You can get 100k miles out of platinum plugs so I don't see the need to spend more for the "Ruth" plugs unless they were specifically spec'd by the auto maker.

I've only used copper, platinum, double platinums and iridiums plugs (as spec'd) so far in my lifetime.

 

[BillyHW]

The location of the spark on the Rutheniums does not look like it is the same exact location as the Iridiums. It is shifted away from the ground side by the length of the platinum ground electrode on the DFE designs.

How could this affect the way the engine runs?

 

[chris719]

The location of the spark on the Rutheniums does not look like it is the same exact location as the Iridiums. It is shifted away from the ground side by the length of the platinum ground electrode on the DFE designs.

How could this affect the way the engine runs?

I don't know, but with GDI engines I would not be wanting to experiment. The Laser Iridium or equivalent OE plug are all I would use. Some of these modern engines are pretty picky and a lot of BMW N54/N55/S55 guys try to "upgrade" their plugs and end up with worse results.

 

[BillyHW]

I don't know, but with GDI engines I would not be wanting to experiment. The Laser Iridium or equivalent OE plug are all I would use. Some of these modern engines are pretty picky and a lot of BMW N54/N55/S55 guys try to "upgrade" their plugs and end up with worse results.

I have a 2.4L I4 naturally aspirated engine. Been using standard plugs up until now, but was researching maybe switching to something super-long life like the Laser Iridiums or Rutheniums which is how I found this thread. I don't care about performance, just want to maintain current performance. I wouldn't mind a very long change interval though.

 

[QX1]

Iridium is already good for 100k, but the ruthenium is definitely worth it on cars where it's hard to do them on. Almost any transverse V6/V8, 4th gen Camaro/Firebird, Aerostar, Subarus, etc.

For cars where it's easy to do them, no need to waste the extra money on the ruthenium

in long run ruthenium pays off.

 

[Snagglefoot]

Almost 5 years have gone by since the OP started this thread. In those 5 years I have not heard any negative news about Ruthenium plugs. AFAIK, they are still considered state of the art and are absolutely good for 100,000 miles. Most people will not have to pull a set out of an engine.

 

[dfarr67]

Almost 5 years have gone by since the OP started this thread. In those 5 years I have not heard any negative news about Ruthenium plugs. AFAIK, they are still considered state of the art and are absolutely good for 100,000 miles. Most people will not have to pull a set out of an engine.

I did- but it was a non stock engine- I like my IX.

 

[dubber09]

Ifaik, Ruthenium plugs are a bit better in ignitebility while maintain other qualities iridium plugs sport.
Change in design where there are two protruding tips helps with ignition yet little more.
I don't see any downsides in using Ruthenium plugs, running them in Forte and daughter's Acura, would in Sportage too if they had one for the engine.

 

[SHOZ]

I use Denso twin tip Iridiums. That's what came in the car OE. No waste spark. If it only has on special tip it's just cheaper to make.

 

[KrisZ]

Does anybody know what these new fancy electrode coatings are good for?

If one is going to adhere to the change interval as prescribed by the manufacturer, I see no reason to use something else than OEM, be it copper, platinum, iridium or whatever.

 

[G350913]

Greetings people who still look at this thread and are also looking for more follow-up on Ruthenium plugs.

I installed new Ruthenium spark plugs(NGK 96355) at 124.2k miles on my 2006 Infiniti G35 sedan(Jan of 2019). Yes I do keep that exact of a record of my car. Yes I am a huge car nerd. It is now November of 2024 and I have crossed over the 200k mile threshold and now sit at 204.1k miles. I was able to get up to 25 MPG during covid, when the highways were empty(I selfishly miss that). At best recently, I have gotten between 22-23 MPG. I think this is due to still having original from the factory shocks, struts, and wheel bearings. I just replaced all 3 of those items since passing the 200k mark(and got an alignment). I am taking a long road trip this weekend, so hopefully I can report back and see what kind of MPGs I am getting because sadly, I am mostly city driving these days and only get 18-19 MPG in mostly stop and go traffic.

I think I am going to run these plugs as long as I possibly can. Be the first true "guinea pig". When I put them in at 124k miles, I expected for them to be the last spark plugs I ever put in the car, but I did new valve covers + gaskets at 181k miles and my engine looked brand new still(see pics for reference). So I'm thinking that my G will actually take me to closer to 300k miles and which case I might actually need new spark plugs again at some point. But for the sake of science, I would like to see how far these Ruthenium plugs can actually go... Because I dont see a single source online saying how long they actually last. Where its well established that copper is 30k, platinum is 60k, and iridium is 100k, etc. I would love to put a number to Ruthenium.

 

[G350913]

Quick update - I was able to get 23.5 MPGs, with some Thanksgiving day traffic. Best in the past 2 years, but also I bet I could do even better if I replaced my driver side, front wheel bearing. I forgot that I only replaced the passenger front wheel bearing 3 years ago because I was still pretty broke at the time (and recently did both rear wheel bearings together... like you are supposed to)

 

[Retirednow]

Getting a set of ruthenium’s for my Ford Barra 4.0 six. They’ll replace Denso Iridium Twin Tips which have been better than the NGK Iridium IX they replaced.

 

[bobdoo]

I think I am going to run these plugs as long as I possibly can.

Be sure to remove and reinsert them at some point, so combustion deposits don't lock them in the cylinder head (assuming some of the sparkplug thread extend past the head).

 

[Snagglefoot]

Be sure to remove and reinsert them at some point, so combustion deposits don't lock them in the cylinder head (assuming some of the sparkplug thread extend past the head).

Ok advice if you can get at them but if you are dealing with the back bank of a V-6 or trying to get at the furthest back spark plug on the passenger side of a Chevy LS engine, I would never run a used spark plug back into a head. It’s just not worth my time. I run my Iridiums for a minimum of 100,000 miles. Yes, it makes a mighty squeak when coming out but no damage. YRMV.

 

[someonesomewhere]

Ok advice if you can get at them but if you are dealing with the back bank of a V-6 or trying to get at the furthest back spark plug on the passenger side of a Chevy LS engine, I would never run a used spark plug back into a head. It’s just not worth my time. I run my Iridiums for a minimum of 100,000 miles. Yes, it makes a mighty squeak when coming out but no damage. YRMV.

My 07 Mazda3 (2.3L) has been the same on both plug changes (75k and 144k)---a mighty "crack" followed by an ear-piercing screech for the first 1/2-1 turn, then they thread out by hand. I assume the crack is from the carbon on the threads that protrude into the combustion chamber, with the screech being caused by the same. Absolutely 0 issues other than the (admittedly heart-stopping) noises when breaking loose.

 

[bobdoo]

I assume the crack is from the carbon on the threads that protrude into the combustion chamber,

I wonder if that carbon could stop a valve from closing...