I have heard all the opinions on breaking in  new engines
on synthetic motor oil, some pro some con. Most people feel that you should wait somewhere between 5 and 15 thousand miles until the rings set  properly. 

There are however a couple of high end automobile companies that install synthetic motor oil at the factory in their new automobiles and who's engines never see anything but synthetic oil, one is Porsche the other I do not remember.
Perhaps they know something we don't.
clarence.
1990 multivan
North Carolina