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Thoughts on NGK Ruthenium Spark Plugs on 9th Gen Si Coupe?

7K views 48 replies 19 participants last post by  J0J0_FG4 
#1 ·
Hi,

My stock daily driver 2015 Si Coupe has 122K miles now and I still have not replaced the original spark plugs.

I'm thinking of replacing them with NGK Ruthenium.

Any thoughts?
 
#15 ·
Long story short my 14 SI coupe had been sitting in the garage for a few months because I got fed up with it was having issues with slave cylinder and master so I had to be in a tight ass and did the full upgrade in the process of it being messed up tore up 2nd.. 😭 and out of nowhere I started getting rough idle and it would cut out when I would give it throttle so I put the coil packs and plugs which mind you aren’t even a year old and they were completely fouled and I replaced the Denso‘s with NGK‘s so I cleaned them up and re-flashed my ECU and it was idling better went to get into it yesterday on the highway and it was missing like nobody’s business literally sound like that was blowed up any thoughts? Sorry for the long post
 
#4 ·
Anyone having bad luck with OEM Denso equivalent NGK's probably got fakes circulating anywhere but the parts stores.

If you get them from a legit vendor that's getting them from NGK directly, you'll have no issues.

Haven't heard anything about the Ruthenium's. My guess is it's probably more cost effective to go with NGK iridiums like Boosted suggested.
 
#8 ·
Hi,

My stock daily driver 2015 Si Coupe has 122K miles now and I still have not replaced the original spark plugs.

I'm thinking of replacing them with NGK Ruthenium.

Any thoughts?
First I've heard of such spark plug.
At $15 a hole they are not that much more expensive than iridium plugs that cost from $7 to $12 a hole.
Me: OEM selection of plugs is my go to.

Note: you got good service from the stock plugs.......
 
#9 ·
First I've heard of such spark plug.
At $15 a hole they are not that much more expensive than iridium plugs that cost from $7 to $12 a hole.
Me: OEM selection of plugs is my go to.

Note: you got good service from the stock plugs.......
I think the intention is longer service life, however if you follow the manufacturers recommended replacement at every 105k miles, then it really doesnt matter what plug you use.
performance wise they seem the same to me.

Have switched to the rutheniums on all our Hondas, there is no long term field use data, so figured I would find out for myself.
 
#10 ·
Installed the NGK p/n 96358 Ruthenium plugs into the R18Z1 engine in my son's 2012 Civic LX Sedan nearly two years ago. He has noted a very slight MPG increase with his long, repeated commutes and always using the same gas pump (pure gas, no ethanol contamination) ... but hard to tell since it already posts great range numbers on a tank of gas.

Also installed these same NGK 96358 Ruthenium plugs recently into the K24Z2 engine in youngest's 2011 LX Accord. Smooth running, maybe slight MPG increase, but that car already does great in that department, too.

I just get these on the NGK.com website. Our 2012 Accord EX V6 Sedan, 2013 & 2015 EX Civics also use the same p/n, so I'm just going to get them all at one time.

OF
 
#20 ·
This is a good article I found.


You can't go wrong with either sounds like. Article says overall Ruthenium has a better and quicker fuel response, which generally results in better acceleration and easier and smooth combustion. The Laser Iridium spark plugs still have a faster response to throttle operations and it also quickly improves the smoothness and impact of the acceleration.
 
#25 ·
This is a good article I found.


You can't go wrong with either sounds like. Article says overall Ruthenium has a better and quicker fuel response, which generally results in better acceleration and easier and smooth combustion. The Laser Iridium spark plugs still have a faster response to throttle operations and it also quickly improves the smoothness and impact of the acceleration.
not a lot of data to back up the claim... but assume there is a reason these are being pushed as next gen plugs.
 
#21 ·
Just stick to the OEM. Unless you are boosted, don’t get tricked into buying a spark plug that is going to run cooler or longer or “better”. It is relevant to the spark plugs temperature capabilities. If you are not boosted, you don’t need heat protection or extra spark nodes. It will not make it run better, that’s a fact. Unless I see some knock count sheets to disprove me, I would never put anything less than OEM recommendation.
 
#22 ·
Just in answer to the pricing queries ...

... the Ruthenium plugs are a little less expensive than other specified options on NGK.com.

Son says his 2012 LX Civic sedan does idle more smoothly. My daughter says the same for her 2011 LX Accord sedan, but I performed a CKP re-learn and valve lash check, so I can't pin that positive result on the fresh spark plugs.

My Acura TL and old Odyssey, wife's 8th Gen V6 Accord, and the other two 9th Gen Civics in our family are all due for a plug change. I'm going to buy the Ruthenium plugs for all five cars from NGK.com and install them this summer and see what transpires.

OF
 
#23 ·
For thoe not familiar with ruthenium spark plugs, here is a bit of science as I understand it.

In spite of latter and apparently superior materials such as iridium, many race cars still run copper spark plugs. One reason may be because they're replaced so often, but the fact is that copper is more conductive than iridium and provides a better spark. The problem is copper only lasts a fraction of the time iridium will last. They moved to iridium plugs was not for performance or efficiency, although there's certainly nothing wrong with them, was to have 60,000 mi and 100,000 mi spark plugs.

The advantage of ruthenium spark plugs, and the reason I believe they are absolutely worth every penny, is that they are at least as durable and long-lasting than iridium if not more so, while having every bit of the conductivity and performance advantage of copper plugs. This makes them the optimal option for daily driver high performance vehicles, with high compression ratios and especially for compressed charge engines.

I hope this proves helpful.
 
#24 ·
@nYdGeo , that is helpful. When we installed the plugs in a pair of Hondas, I could swear the idle seemed smoother.

Both our 2011 Accord LX and 2012 Civic LX originally felt "coarse" in their idle quality, if that is a way to describe it. Could not get any misfire counts on my Foxwell NT510 scanner, so I thought it was something we were just stuck with.

The Ruthenium plugs seemed to have changed that. My son and daughter have both communicated the same to me.

OF
 
#34 ·
I've had bad luck with NGK spark plug internal resistors measuring between 1.5K to 7.5K ohms and they never seem to be consistent when purchased brand new from Rock Auto. Personally, I don't see the need for Iridium or Ruthenium spark plugs when the tips are laser welded on with a much smaller in diameter electrodes which have been known to break off. I prefer to use the Denso brand double platinum spark plugs and just change them more frequently.
 
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