Never have used a VOM on a plug but have cleaned and checked the gap on plugs for years and seldom replace one has been my experience.
Humm.. "Seldom replace one"
Another related question is what plug to use for replacement.
I always get whatever the manual calls for, but some mechanics seem to disagree.
They purposefully install a hotter plug.
Or 1 guy seems to think if it's the same physical size, and it cranks then it's OK. :ashamed:
I don't know about this...
Home Depot has a line of "E3" plugs that are maybe $5.68 ea vs $2.38 to replace a BPMR7A.
On this package it has a long list of plugs that this one will replace.