At 68,400 miles, I removed the OE NGK IFR7X7G spark plugs. They were replaced with NGK BKR8EIX plugs. Attached photos at 90,500 miles show on Left the OE’s -IFR7 when removed (two showing with 68,400 miles), on Right the replacements -BKR8. Replacements have 22,100 miles on them. Gap in that period grew from .033 to .045 - wear approx. 1,840 miles per .001” - seems like a lot. Note the burning marks on the BKR8 ground electrode, not on the IFR7 with triple the miles on them(is that the plug blowout some have discussed?). Also, insulator color has changed to gray from white. In the future, I will check & regap at 9,500 miles(every oil change). I did NOT notice any MPG or performance change with the BKR8 plugs. However, back in 2012 at 18,400 miles on the OE IFR7 plugs, when I regapped from the factory .025” to .035”, MPG went up & Cruze accelerated smoother. The same holds true for the BKR8 plugs.
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