[lowrydr310]

Have an old 325i and I replaced spark plugs and coils 35K miles ago, using NGK 6619 LFR6AIX11. A family member has owned the car for the past few years and it just started to misfire intermittently. The center electrodes (iridium) are fine on all the plugs but the ground electrodes are severely worn on all six. I'm not used to seeing this on iridium plugs. Any specific reason why they're so worn? The 2006 maintenance interval per the computer is 100K, though I know BMW has shortened that interval and changed to platinum plugs.

[mainbearing]

The Iridium IX plugs do not have platinum ground pads on the ground electrodes. Even then I would think those plugs should last longer than 35K miles.

Anyway, try their "Laser Iridium" with platinum ground pad ILZFR6D11 (check the part number). Some like the newer Ruthenium HX LFR6AHX-S, but others said the plug causes misfires. I have not tried ruthenium plugs.

[james11109]

I installed NGK 94122 LFR6AHX-S Ruthenium HX spark plugs to my E90, 2 weeks past, it still running very well without any error code appeared.

[The Nightman]

Old thread but yeah, LFR6AIX-11 have iridium center electrodes but nickel ground electrodes, and are only rated for 50k miles:

https://www.ngk.com/ngk-6619-lfr6aix...-ix-spark-plug

Originally Posted by james11109

I installed NGK 94122 LFR6AHX-S Ruthenium HX spark plugs to my E90, 2 weeks past, it still running very well without any error code appeared.

Good to know Ruthenium plugs work. I like the twin tip design