Spark Plugs-Heat range
do a general search online for the above, there's mass info out there on this subject...besides whats said here...what works for me, might not work for you, or the next guy...
my car is using the XP 5144 IRIDIUM's - this time out, i did do a regap to .045, got a killer deal on them - so figured id try them out, the car runs out strong, plug color is where it should be, and i dont have a problem changing them or checking how their burning, which seems to be an issue for some, in general dont over look the ignition system used on the car, this means the whole ignition system, not just a set of plugs, how about plug wires ,are plug wires, A--equal to plug wire B, or is coil A equal to coil b, our the outputs the same, anyway - - depends on the app., of the car, mods, driving style
cheers