OE spark plug question

[Volvohead]

Yeah, I know. And I don't mean to rub any salt in those Ford owner's wounds.

But it is a vivid "nightmare" illustration of what happens when the plug won't/can't come out.

I also subscribe to the "turtle cooking" scenario for plugs. The decline is so gradual that most drivers never notice. While the plug is still "good" at 100k, it's probably not as efficient as it was at 50k. With gas at $3-4 gallon, on a bigger thirsty V8, the fuel savings across 50k might justify the early change v. the 50% cost amortization on eight plugs.

Generally, spark plugs are pretty inexpensive parts as parts go.

 

[Gokhan]

All NGK and Nippondenso plus are plated and there is no seizing issue. The only reason why they would be difficult to remove would be that they were overtorqued.

Do not remove and reinstall spark plugs because that causes the plating to come off, which leads to seizing.

 

[PandaBear]

Originally Posted By: BigCahuna
Since no auto mfgr actually MAKES spark plugs, No one can prove they are the best. Harley plugs are a classic example. They're made by Champion, who also sells a plug that looks exactly the same, without the Harley name on it for less $$$. With the way cars are made these days, computers control every aspect of ignition. A super duper factory trained tech could not tell just from driving a particular car ,what plugs are installed in it.Use whatever brand you want, as long as the plug mfgr says it's for your vehicle. And change them every 50-100k miles.,,


But auto manufacturers TEST AND CALIBRATE their fuel and ignition according to the plugs they buy from others. That's the biggest advantage if you buy from the right OEM and the biggest problem if you buy from the wrong one.

So for example, if you have a Ford that uses AutoLite from the factory and the fuel / ignition map and the heat range are all calibrated for this plug, and AutoLite sell the exact same one in parts store, you win with cheaper prices for the same design.

However, if you use an aftermarket plug on a low volume car that is not the OEM of the factory, then they may just find the closest plug to the OEM design and assume it works. You may get a plug with heat range that's too far off, different gap size (if pre gapped), different electrode design, etc and it doesn't run well, and you lose out compare to buying OEM or other brand in this case.