FYI, Mobil Gear 627 is an ISO100 oil viscosity, the XP150 is an ISO150 and may be a bit too viscous. Mobil DTE Heavy is an ISO 95 gear oil, around $25 a gallon when on sale at ENCO, probably a good choice. Usual lathe gear and carriage oil is often an ISO68 (Mobil Heavy/Medium or DTE 26 motor oit SAE 20), but probably doesn't matter in this application since it is such low stress. This is also what is recommended for the oiler ports. If a auto gear oil, probably stay with a 75W90 and avoid those listed for limited slip or synchro transmission gears (which use modifiers to increase frictional drag). I find the standard Mobil gear and way oils to work well, so stick with them on the lathe. Since this is a belt drive with no head stock gears, not really much in the way of break-in procedure.