Oil Thread
You may well have started a FLAME WAR as most have their likes un bothered by any facts .
Use good quality modern multi - viscosity oils , 5W- anything , 10W - whatever , 20W-50 , etc. as long as it's DIESEL RATED and CHANGED WHILE BLISTERING HOT you'll be fine .
Modern oils are way better than anything available when your old Babbit Pounder was designed and built .
OIL IS THE CHEAP MECHANIC .