I have no where near Randall's experience and don't remember ever replacing a drain plug, so just assumed they were BSP, but the point was that the the TPI and pitch on both are close enough in most sizes (3/8?) that either will screw into the hole, but of course cause a leak if mismatched.
That plug is one of the few places on my engine that I don't ever remember leaking. No sealant, dope, tape or goo either, so probably a good idea to look above it.
Tom