It's been 25K miles since I've run the NGK BKR5EIX Iridiums in the C36 powered wagon (M104.041 engine w/HFM).

I've had no issues with starting (cold, warm, hot) in all weather (27F-102F), and I pulled them just to take look.

The insulator is clean & white, and the electrodes are SUPER clean. Gap is has grown from 0.032 to 0.033

I have a new set of Bosch F8DC4's waiting the wings, but I've read these Iridium plugs can go 50K miles.

My master AST tech was the one who told me these Iridiums are the only known working replacement to Bosch copper-cores.

He didn't recommend ANY platinums.