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??
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??