Ruthenium Spark Plugs

I decided to replace the stock plugs in my 2016 Impala Limited at 60K miles. Since I've always had excellent results with iridium plugs, I was planning on picking up a set of those, but when I started browsing Rock Auto to see what was available, I noticed something new - ruthenium plugs. Hadn't heard of them before, but they are supposedly the new Top Dog in spark plugs - longer service life, better ignitability, faster throttle response, blah, blah, blah. We've all heard it before. But after I did a little more research, they seemed legit. And since they were only about a buck and a half apiece more than the NGK iridiums, I thought I'd give them a try.

The stock plugs were in surprisingly good shape when I removed them, with gaps all still right around .040. There was some carbon buildup around their bases, but that was it. They looked like they'd easily go another 50K miles. But I was already committed, so I went ahead and replaced the them. Besides, the stockers had been installed dry at the factory, and they were already beginning to seize to the aluminum threads in the heads. Getting them out without damaging the heads might have been a real white-knuckle affair if I had waited much longer.

The new plugs I installed are the NGK Ruthenium HX P/N LTR6AHX (91276) for anyone who is curious. These plugs employ NGK's DFE (Double Fine Electrode) design, which means that both the positive and the ground electrodes are fitted with very tiny electrode tips. The plugs are pre-gapped at .044", which is slightly larger than the factory plugs, but they appear to work perfectly.

I've just finished installing them and WOW! I have yet to put any miles on the car with these plugs, but the idle is so smooth that it's as if there's a turbine running under the hood. The motor never idled this smoothly with the factory plugs. I'll update this thread after I've had a chance to assess the car's performance and fuel economy over a couple tanks of gas. I'm not expecting any great improvement in either of those departments, but who knows?

Incidentally, no need to loosen any motor mounts and rock the motor, or to remove any hoses or harnesses to change the firewall side plugs. Just pull the modesty shroud off the top of the motor, and the right combination of extensions and a GOOD 5/8" plug socket will get 'er done. (See THIS YouTube video for a visual.) I could clearly see all the COP locking clips and retention bolts if I leaned far enough back in the engine bay, and I was able to get my torque wrench on all the plugs and COP bolts, so I could tighten them to spec. Again, the right combination of extensions is the key.