I'm not sure if there is a problem or not. I think the 7 in that indicates how cold the spark plug is and I think you're supposed to have 6 and not 7, but I'm also not sure how much of an impact that would make if any.
i think BOSCH FR7 DCX will work better than the NGK BKR6E-11 on the nubira 1.6L stock 7m.m. spark plugs, and also if there was a different between the two of them, i think a good after market 8m.m. spark plugs would solve it and will perform better than the stock ones....
I've looked at NGK and BOSCH wed sites and both plugs are listed "medium hot".
At my basic (cool) driving level I feel the engine smoother but this is maybe due to new oil/filters/plugs combination.
BTW FYI I changed the serpentine belt too. Old genuine one was 6PK1875 (p/n:96183108) and new one 6PK1892(p/n:96309968). A tad longer and easier to fit on. .
Yea oil can make huge difference. Hey if you find it on sale, you should try a ester based oil, insted of petroleum based oil like most "sythetics". Redline and Amsoil are two that use it. Its the same oil used in most aircrafts.
Stay in control with Hankook's weather...or not technology.
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