Hazem A

I was under the impression that NGK Ruthenium advertised as a High Ignitability plug would save significant gas milage especially with its high durability or long service life, so i bought a set of 8 pcs from rockauto along with a new set of GM genuine wires for my 2015 Seirra Denali 6.2l NGK 90220 Ruthenium HX High Ignitability; Pre-Set Gap: 0.044" Info Few days after replacement, I started to have random misfire code P0300. Spent few days trying to diagnose the problem and the misfire was eliminated after reverting back to ACDelco 41-114 OEM plugs except for Cylinder #. 8. Apparently, the injectors were affected and now i have to bear nearly $1000 USD to replace all 8 injectors, fuel lines and fuel pipes. I regret going for aftermarket parts when it comes to essential engine components and will never do it again. The conclusion: I wouldn't recommend going for NGK Ruthenium plugs under any circumstances. Genuine Iridium OEM plugs with 0.04" design gap offer excellent service life without an issue.