Plug Readers Chime In

The length of the heat path from the tip to the shell determines the plug's "heat range" (how hot it runs)—shorter path = colder, longer path = hotter. If it were possible to look at a plug and accurately see the length of that heat path, then we'd look at a plug with an extended projected nose, such as the ZFR5N in this thread, and call it a hot plug (or extra-hot, or too hot…) because it looks like the heat path is extra-long. But it's not possible to eyeball this, because of the part of the heat path we can't see. This NGK ZFR5N with its extended projected nose has the same heat range—the tip runs at about the same temperature range—as an otherwise identical NGK GR5 with a regular nose, that looks like it has a much shorter heat path. They are both in NGK heat range № 5. Or if you prefer to speak Champion, an RN13LYC (with extended projected nose) has the same heat range—runs at about the same tip temps—as an otherwise identical RN13YC (with standard nose); they're both in Champion's heat range № 13.

Anyhow, there was no indication in any of the pics in this thread that the plug is too hot for the application.
Very interesting I was always told that the extruded porcelain was the tell tail sign of the heat range , because it hung out so far into the combustion chamber , and would stay hotter than one that was tucked way up inside the plug ? Colour me blonde.