hummm.... Not sure what to think about that one... I am leaning toward following the owner's manual on engine break-in. If I recall the conversations with my mechanic, I thought there was more to it then just piston rings... If I remember correctly, you are also waiting for the bearings to completely lube with oil. When the engine is put back together, they use that oil substitute to keep everything lubed until the oil can completely lubricate everything properly...
Not an expert, just recalling conversations with my buddy and mechanic...
CLoud