New or serviced parts need adequate initial lubrication when the engine or\npower train is first started.\n\nThe general rule is if it moves, lubricate it. Most mechanics simply use\nengine oil on parts as they are assembled. This provides an antifriction\nfilm until the driven pressure/splash oiling system circulates oil from the\nsump(s).\n\nMy theory is passageways are void after a rebuild and it will take a\nconsiderable time for oil to circulate to normal flows. New and rebuilt\nparts are rough and generate considerable friction until they are well\nbroken in. Thes parts need extra lubrication for their protection. I\nsuggest instead of engine oil, grease be substituted.\n\nGrease is simply oil suspended in various soaps to keep the oil in place.\nThat is the objective, to keep oil in place until the oil pump can come up\nto speed. I recommend "pure white" grease sold in any auto parts supply\nand labeled as such. Liberally coat every part: valve stems, main and rod\nbearings, wrist pin, rings and piston grooves, gears, and essentially every\npart which has relative movement with respect to the other.\n\nThe grease is rapidly absorbed by the oil (engine or gearbox) after it has\ndone its job. Avoid moly grease and other non-pure greases as some\ncontamination of the regular oil is inevitable when those exotics are\nemployed.