Electric motor oil is typically 20 wt for 1/4 HP and up. (3in1 Light Blue label)
"Sewing Machine" oil is 17 wt for fractional HP motors. (3in1 Black label)
30Wt goes in the crankcase of the compressor.
Bearing oil does have detergents, compressor crankcase oil does not.
Nice to see such a good reply! I find that most of the time, people have no clue about lubrication and the importance of using the proper type and grade of lubricant, which depends on load, speed, type of friction to protect from and temperature.
Which is exactly the reason why larger, heavier motors that don't run as fast require oil with greater viscosity which would bog down fast, light motors such as those in portable drills.
Same thing goes for gears. Ever wondered why old machines with huge gears use a tar-like lubricant and why angle grinders need fluid grease? That's the reason right here.
For anyone else interested in lubrication, I highly recommend machinerylubrication.com. They have excellent articles that it explains it very well.
On another front, I just missed a deal on a working Quincy 325 and 5HP 550V motor and no tank for $150. By the time I had looked into phase converters for the motor, it was gone.
