I agree w/ rusty, back in the day-the hemi never knew what oil was in it, and it didn`t make a tinkers dam. we always used 40 or 50 weight oil of a name brand, usually who ever furnished it. break-in or not, never had an oil related problem,or an additive either, course they all had zink back then
will probably use rottella 15w 40 for the break-in of the 505 when I start it.
just my 2 cents worth-----------bob:argue:
