<VV> Strange squeek noise

[Chris C, Warwick RI]

Changed the oil last night.  Ran the exhaust out the door, about 8 feet of 
pipe.  After the motor had settled down and started to heat up, I heard a 
light sqeek/squeal sound.  Like a small mouse was trapped somewhere.
Light enough that with the exhaust normal you could not hear it.

Was letting the car fully heat up before changing the oil.

The car was tilted on about 8 inches off level.  Under the car, and over it 
could not tell where it was coming from.

Could this noise be the the fan.   If so how do I grease it, and does a 
specialty tool help.  When next I can play I was going to duplicate the 
situation, but remove the fan belt.  This would eliminate the fan, and the 
alternator from contention.