| Some motors and squirrel cages do have oiler holes to insert a couple drops into every 6 months to a year, but yes it could also be a loose mount.
First thing to do is go down there and do a good inspection when you hear the noise to see if you can narrow it down...and check your owners manual as to whether it has oilers.
On the downside, it could even be that the bearings in the motor are shot, and in that case, oiling now will do little to no good.
For stuff like this, I like to call a repairman for a free estimate...and once he ID's the problem then I make a decision as to whether it's something I can or want to do on my own. | 
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