I've had no problems using regular detergent motor oil for motor bushings, for decades. Tools, fans, whatever. 5W-20, 5W-30 before that.
The main thing is, either relube before it runs dry and starts chewing up the bushing, -OR- once you're hearing noise, you need something more viscous, how viscous depending on how bad the wear, or else the shaft wobbles too much and pumps the lube out. However if I had to go higher than 80wt gear oil, it would be short term till I replaced the motor or whole widget. This is almost exclusively a case where someone abandoned something, I've never let a motor chew itself up that bad in my presence.
On the other hand, I wonder if this is a trust washer issue. Maybe there was one and it disintegrated?