Oiling motor bearings

[ilpufxit]

My 8ight thermalled last night. It normally won't even get hot. I'm running a Neu 1512 2.5 d/f on 5s. Quark 80b. 14/46. It seemed to be hard to roll even with the power off. When I pulled out the motor to see what was tight, it was the armature. Not really tight but enough so I could tell there was more drag than magnetic resistance turning the pinion by hand. I applied some bearing oil to both ends of the shaft and after a little spinning it seems much more free, still notchy from the magnets but no more drag.


So, my question is, should I normally expect to have to oil those bearings and if so, how often?