Good catch, I didn't notice that. Probably not a typo, as NGK is Japanese and does things metric, while Sac Sky Ranch is US and probably uses English units.
900F is 482 C if I did the conversion correctly. That says that lead fouling should not occur above 482 C? Not my experience.

Aviation in the US uses a strange mix of units, AWOS reports altitudes in feet but temperatures in C.

>Charlie England wrote:

>The quote for carbon uses C; the quote for lead uses F. Is one a typo?