1Lop2K5C

I decided to change out the plugs soon. For NGK, I came across two parts number and they seems both recommended for the M113 AMG engine.

NGK-ILFR6A
NGK-IFR6D10

Does anyone know the difference between the two?

JToups386

NGK - ILFR6A = their "Laser Iridium" series which is an OE style replacement for the 2003 S55 AMG

NGK-IFR6D10 = their "Laser Iridium" series which is an OE style replacement for the 2006 C55 AMG

If you actually go on NGK's website and type in your application for a 2005 C55 AMG, you'll see their part number recommendations as being;

NGK Laser Iridium OE replacement = IFR5D10 (approx $12 per plug)
NGK Iridium IX = BKR5EIX-11 (approx $16 per plug)

For some reason there appears to be a change in the recommended heat range between 2005 and 2006. You would be fine with either one.

Saaboteur

Bringing back this thread from the dead.

I've been looking for plugs for my '05 C55 and can't seem to find a definitive answer. Here's what I've found:

owner's manual - ILFR6A
NGK Canada and NGK Germany websites - IFR6D-10
sparkplugs.com - IFR6D-10
NGK Canada website also says BKR6EIX-11 is suitable, but when that number is input into the sparkplugs.com cross reference app, it does not list the the C55 (nor any Mercedes actually) as an application. Instead, it lists a whole pile of other cars, mostly Japanese.
NGK US website - IFR5D-10

The ILFR6A and IFR6D-10 are NGK's 'Laser' series, supposed to be good for long life. The BKR6EIX-11 is NGK's 'Iridium IX' performance series. I was hoping that I could get the Iridium IX performance plugs for my car, but I'm not sure that there is a suitable cross reference now.

I think the IFR5D-10 must just be a different heat range from the IFR6D-10. Come to think of it now, I think I might have the BKR6EIX-11s in my S2000, as a one range cooler plug than stock for my supercharged application.

Any ideas? If nothing, I think I will head with the IFR6D-10. Interestingly, the sparkplugs.com cross reference app lists the ILFR6A as the SLR McLaren as an application. The engine in that is a built M113 so that would make sense I suppose, in that it should physically fit the engine.