I just went through a seriously long engine replacement due to scored and slapping pistons... (at 8,000 miles, I bought her used and got a nicely used engine as well). Anyway... the new engine, was a complete unit... all new... dealer took over 60 days to build it. No break in required, no short time oil change, no special needs or requirements as mentioned by the building mech. Just drive the car as you normally would and don't worry. She runs like a charm, I'm happy so far.