My garage door has developed quite an annoying squeal over time. It's only around 3, maximum four years old. It's an impact garage door that I added some time after moving in. When I first got it, all you would hear is the motor and the inevitable sounds of the door shifting as it travels up or down the rails.
There is a pretty simple fix to this, and that is to lubricate all of the joints, wheels, rails, and the shafts that hold the wheels in place. Now, many people will try to use something like WD 40 or grease for this purpose. This is not really the correct application for them. The correct lubricant for this purpose is a silicone based, spray on lubricant. A general one works, although they also make ones that specifically say they are for garage doors - that takes the guess work out. I used such a can in this quick project and had great success.
The mic I am using is pretty sensitive, to the point where you can hear me breathe, however you will notice a great reduction in squeal/squeaking of the door as I proceed. Best of all, if the door to the house is closed, I can't hear the garage door at all until it hits the bottom and makes its "thunk" noise.