OK blow by, is blow by, pretty much all of it is past the rings.
You just don't get significant blow by anywhere else. A little blue smoke on start up may well be valve guide seals
, oil leaks
past when the engine
is off and burns off at start up. Annoying I guess, but nothing to be real concerned with, but excessive blow by means rings are not seated, or are worn out, cylinder walls glazed etc.
Assuming it was in fact "rebuilt" which is a term that means different things to different people, it should mean nothing is worn out, leaving rings that didn't seat.
Without disassembling the engine
the only real way you can seat them is to run it hard, this build high cylinder pressure, which forces the rings out against the cylinder wall which hopefully will make them "wear in" or seat.
Do not change to a thicker oil, your using excellent oil, that's not the problem. Go to a single
grade if you like, but you may either try to seat the rings, or just live with it, or take her apart and find out what the problem is.
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