how many miles break in, before switching to synthetic motor oil ?

Yeah, depends on the rings, but chances are, you did it a little too early. I say 100 miles, and my rings are seated almost fully within minutes. Waiting gets the first early oil change done so there's not so much moly and crap still coming off the parts with the good oil in it.

Edit.. That was supposed to be 1000 miles... lol. Sorry.... cant believe I missed that.