What Oil is Best for My South Bend Lathe?

This subject comes up on most Machinist groups and Metal working forums with annoying frequency, to the point of irritating regular members. Its a perfectly natural question for any new machine owner to ask; we all want the best for our machines. The discussion usually degrades into name calling because one guy uses chain saw bar oil for way oil, and another guy uses only the “factory specified” oil. I have never seen any five machinists who could agree on what is “the best” oil for your lathe.
To put this all into perspective, I’ll quote from what many people feel is the Holy Grail for oil selection; South Bend Lathe Works publication : How to Run a Lathe;


Many people will not deviate from the specifics in this book at all. I think it is important to remember that alot of this info dates back to World War One (technology has changed some), and most of our lathes predate World War Two. With the advent of synthetic lubrication and the wear associated with years of use, Read more