Ill keep this simple
actually during the break in period in a engine the asparites of the
internal parts of a new engine will wear down until the engine is "BROKEN
IN" and the rings seat with cylinder walls and stuff like that.( the
asparites are always wearing down throughout the life of a engine) when
using synthetic oils the additives in the oil may prevent this from
happening and may effect how the engine breaks in as one would say. Not sure
what you mean by shavings? or where you got that from .