In most cases the new motor should come with break-in instructions to be followed to meet their warranty requirements. One thing to keep in mind is that most new engines (or rebuilt ones too) Do not use synthetic oil for break-in. Most manufacturers ask that you do not take any long trips where you keep the load on the engine at a set rate for longer periods of times. They want you to run the rpms up and down to wear in the rings and pistons. Make sure you find out what weight oil they recommend for the break-in period. Most of the engines I have done say the break-in period is 500 miles. But, like I said before, contact your engine manufacturer to get their requirements under their warranty.