I was wondering if I were to install the hotter leading plugs in a car that does 75% city/25% highway driving in North Carolina harm anything. Basically wanting to know if the hotter plugs will clean the chamber better and make more of a complete burn without harming the motor. I don't have any problems just kinda curious as I do mostly city driving and the these are for city driving and cold weather (which we have less of).

 

Thanks for asking (no...I can't help..lol...but) I wanted to know more about this hot/cold plug thing. Why go hot or cold, why is one better than the other, etc? Does anyone have any specific data showing the benifits or problems between the two?

 

A hotter plug will not clean the chamber better, per se. Hotter plugs will themselves operate at higher temperature and thereby (at least in theory) burn off more of the residual carbon and/or oil that would otherwise remain on a colder plug. This is particularly important as far as the center insulator of a plug is concerned, since that is where shorting of the charge in the center electrode usually occurs, weakening the intensity of the spark delivered to the other electrode across the gap. AT least in theory, a hotter plug will remain "cleaner" and thereby provide a more effective spark to ignite the fuel-oil-air mixture.

For your driving habits, unless you redlining the engine frequently or driving at very high highway speeds, a hotter plug should be OK. But unless you are having hard starts or, perish the thought, no starts, you probably don't really need the hotter plug.

 

Correct, the hotter plugs were for the L flash flooding issues only. You do not need them anymore if you have M or N flashes.

 

Going to heat range 6 for the leading (instead of "7") never was the "best" thing to do. It was a "better" thing to do given what was available. Note the tradeoffs that Mazda stated in the TSB. The best alternative was to redesign a "7" to address the issues at hand. This took time and is now available - N3Y8-18-110 (RE7C-L).