Spark Plugs: OEM vs Aftermarket

[Jmaz]

I think the OEM Mazda ones are branded NGK just with Mazda Stamp branding on it . Well anyways i replaced my original mazda spark plugs with Denso Twin Tip Iridium they works excellent no issues & great for value.

Great, thanks for the tip on an alternative plug. And follows along with Japanese plugs for Japanese cars.

 

[minnesotaart]

The easiest thing to do is check the resistance of any new NKG plugs and compare to the published NKG specs. Genuine plugs are consistently in spec and fake plugs are all over the place. You can also, like I did, send closeup pics of the plugs to NKG and they can tell you if they are genuine. They have a LOT of experience seeing the fake plugs up close.

 

[RedBaron]

The easiest thing to do is check the resistance of any new NKG plugs and compare to the published NKG specs.

That's interesting... never seen that mentioned before. Do you know offhand where to find the specs?

 

[Jmaz]

That's interesting... never seen that mentioned before. Do you know offhand where to find the specs?

The 2013 Skyactiv shop manual ( for the 2.0 L engine) shows 3.0-7.5 kohms under spark plug inspection procedure. The NGK's I installed last summer ranged from 4.61 - 5.15 kohms and I remember checking the original plugs and they measured around 5 kohms also.