As Larry (and others) have said, the break in period is a thing of the past to a great extent. If you look at the bearings (main, con rod, cam) etc, the better your oil, the better any initial imperfection can be handled. Cam lobes are either OK or ruined, primarily in the first couple of minutes of running...if the factory didn't lube them right for initial run, they will most likely be toast in a few thousand miles. The major components, that in the past, required sensitive break in procedures were the ring faces, ie, where they contacted the cylinder wall. In the past, the manufacturing process for rings had a hard time creating the ring in its relaxed configuration so that it was perfect in its compressed configuration while in operation in the cylinder. New technology allows them to accurately predict the correct shape...that's why the cylinder wall can be so much smoother now than in the past....the ring doesn't require the final "lapping" process (the break-in period) to ensure the perfect fit as it once did. Another thing to think about...rings receive very little lubrication, especially the compression (top) ring...I want the very best oil I can get there, and that's synthetic oil.