Originally Posted By: Trav
Originally Posted By: PhuongFU
I have a 2003 Mercedes clk500. According to ngk my spark plugs should be gapped at .040. I just bought some of their iridium ix plugs but they are pre gapped at .044. Should I adjust them or leave it as is? Will .044 give me better gas mileage? Thanks in advance.
The IX is not a double precious metal plug and gap erosion could be an issue when run for a longer period of time. As you are already starting out with a larger gap this could happen sooner.
The OE double platinum (or equivalent) does not have this issue and the slightly wider gap is of no concern.
If i were doing this job i would go with the Bosch 8100 (FR8DPP33X) which is OE as my first choice or the NGK PFR5R-11 as an alternative.
+1^^
NGK's Iridium IX; Platinum G-Power; & conv. V-Power lines ARE NOT pre-gapped for their application, however they are pre-gapped precisely to one of various NGK standard gaps which may or may not coincide with your vehicle's required gap. In this case the plugs come gapped at .044" which most vehicles that use this plug specify, but not your car.
I would re-gap them, but be careful, since iridium is much harder than steel it will dig into your feeler gauge, possibly breaking the electrode if you yank it loose.
NGK's Laser Iridium & Laser Platinum do come pre-gapped for their application, on these two lines you should only check the gap to make sure they haven't been handled roughly.
