The right oil

[mat in tn]

Define better. Modern synthetics have superior cold performance. If I could get 0w-30 something other than expensive race oils, I'd run it. Most wear occurs during warm up due to the oil being cold and thick. Not to mention thinner warm oil results in less drag and less work for the oil pump, which improves efficiency. Finally, modern synthetics can be run on a longer oil change interval (less sludge formation). The only downside: synthetics are more sensitive to oil leaks; they won't cause new leaks, but they can make existing ones worse. My 300 leaks pretty bad from the valve and lifter covers... After a rebuild! Now I know why a PO Indian Headed the old gaskets (which were also leaking, and were a real pain to remove!).

Also, break in oils (or oil with break in additive mixed in) are supposed to be less lubricating... that's what allows the rings and cylinders to break in. Once broken in, that's *not* what you want!

all very good points. that is the reason why there are so many different products on the market. one size certainly does not fit all. engine design, bearing surface, bearing size, journal diameter and oil clearance all come into consideration. I do prefer to use the thinnest oil for the job for the same reasons you mention. faster response to start up being major. lately there have been many reports of lifter failure, both flat and roller. I currently have one lifter in a 5.0/roller that refuses to pump up fully. still in line to be replaced. in the meantime, I can always rely on my 300.