I first noticed the Ruthenium a year or so ago. As far as I can tell it is just another precious metal with very similar physical properties to Platinum and Iridium.

Biggest difference though is ... PRICE

Current prices in US dollars per ounce:
Platinum: $969
Iridium: $1495
Ruthenium: $255

So I can see why NGK, etc. would rather use the Ruthenium if it is just as good, and maybe better.

UPDATE: after getting genuine NGK Iridium plugs and installing them. I could definitely tell the difference in the butt dyno. For sure better throttle response than stock plugs and for sure the counterfeit crap iridium plugs I had in there. So I decided to try the Ruthenium plugs. Swapped out the Iridiums I had been running for a month or so. They looked great. As expected. Put in the Ruthenium plugs. Same good throttle response as with the Iridiums. They run very smooth. Seem even smoother than the Iridiums. Of course, that's totally subjective. We'll see how they hold up.

Good deal. I change my plugs out more often than most people, gonna give these a try as well.

I too recently replaced the spark plugs in my X with the Ruthenium plugs. They seem great on the butt dyno!

Nice interesting catalog that NGK has promoting their Ruthy plugs. Seems to be a direct competitive replacement to the denso TT plugs.

https://www.rockauto.com/genImages/100/ruthHX.pdf

https://www.rockauto.com/en/catalog/...park+plug,7212


EDIT: Saw someone posted the catalog too..just in a different spot.