Review on NGK (93618) SIKR9A7 Iridium Spark Plug with Laser Technology by Chris Nonamaker

These are the exact same candles from the factory. I just installed them at 30K in my 500L and what I pulled out was an NGK SIKR9A7. They showed some wear and signs of sparking between the ceramic insulator and the threaded body. I've never changed this type of spark plugs (special alloy) so quickly, but on this high performance engine, as the manual says, they need to be changed every 30,000. Spacing was set correctly from the factory so I just used an anti-seize and they passed easily. In fact, changing the spark plugs is quicker and easier than changing the oil! The only minor obstacle was the crankcase tube. Just quickly tighten the clamp, remove, and the first coil can be removed. The other 3 are free. If you're reading this and thinking about changing spark plugs, order these spark plugs, anti-seize and go. I was skeptical, but after removing the first stub, it was clear they were right about the 30K mark. The car idled like new, very quiet, and seemed to start faster and a little snappier.