This may seem obsessive to some , but on a freash rebuilt, I always fill with regular oil of recomended wt, run without load ( idle in the driveway) for 10 or 15 minuits, and drain it and change the filter( this is to get the leftover chips etc out without grinding them into the bearings).
Then drive lightly for 100 mi and dump again.
Then run 500 ( still refraining from flooring it )and change again.
then run 3000 mi and dump it and switch to the synthetic.
For break in , just about any of the quality petrolium lubes will do.
Avoid the temptation to use cheap filters for the break in period, this is when you need good ones most.


------------Robert