Lubricant for squeaky doors
Properly lubricating the hinges should stop the squeaks.  In short, you remove the hinges from the door, lubricate them, and put them back.

You'll want to use white lithium grease.  It works very well for metal on metal contact.

I'm assuming simple door hinges here, like these



You'll want to do each door one at time.  

Long Process


Have someone support the door while you knock the hinge pins up and out from the bottom of each hinge. 
Lean the door up against the wall and unscrew the hinges from the door and the jamb. 
Lay out the hinges on newspaper and use the lithium grease to lubricate the pins and the inside of the barrel.  The barrel is the tube that the hinge pin passes through, 
Usually, you let the lithium grease dry before reassembly.  Follow the directions on the grease.
Finally, re-attach the hinge wings to the door and jamb.
With someone holding the door, re-insert the pins from the top.
Enjoy the silence.


Short Process


Have someone support the door while you knock the hinge pins up and out from the bottom of each hinge. 
Lay the hinge pin on newspaper and use the lithium grease to lubricate it.
Usually, you let the lithium grease dry before reassembly.  Follow the directions on the grease.
With someone holding the door, re-insert the pins from the top.
Enjoy the silence.


Do one door first, and give it few days to make sure the squeak is gone.