Break in
As stated above - RTFM (Read The Frickin Manual). GM doesn't print them just to kill trees.
On a personal note, I have had very good results by following what a mechanic told me. That is, for the break in period, be sure to vary the load on the engine - both on acceleration and deceleration. This variable load causes the rings to expand and contract, thus "seating" them properly. That does NOt mean to go out and beat the heck out of the car but it also does not mean drive at an easy, grandpa pace all the time.
For the last four cars I have owned, I have had zero engine/oil related problems and no oil burning. All four vehicles went well past the 100K mark.
I am not a mechanic, I just pretend.
My humble $.02