Seems to me I vaguely remember that there were a couple of
different types of crankcases: one had a big cavity behind the seal so
that there was no problem draining the oil away from it, and the other
had a small drain hole that guck would plug up so that the oil was
eventually forced past the seal. Pressure from the front main would do
it.
But this is really vague and might be applicable to some
other engine. My memory isn't what it was.

Dan

My hypothesis is that too much new data forces a lot of old memory out the
drian hole, or past the seal.

That's my story an' I'm stikin' to it.

Peter