Originally posted by hobieboy
Bosch & NGK uses different numbering scheme.
NGK plugs - smaller # is colder (7 is colder than 8).
Bosch is reversed.
I think a NGK BP8 range is similar to Bosch WR4 range.
Actually, it's the other way around with NGK. The lower number is hotter and higher is colder. The link to NGK's chart, that KCPSG posted, confirms this. I couldn't figure out which would work best for me so I just bought a set of BP7ES and BP8ES plugs.