Hampton bay fan noise
The fan does not need to be oiled. The bearings are what manufacturers described as "permanently-sealed", which means that they're designed such that they don't require oiling. The manufacturers recommend against oiling, and if you really wanted to do it, you'd have to be an expert, because there is some very complex disassembly to be done, which requires specialized tools.
The problem is not related to oil. A lack of oil does not produce a hum. If a fan's bearings are low on oil, the sound generated is a scraping or brushing sound. A hum, on the other hand, is an electrical sound. All fan motors hum to some degree -- the cheap made-in-China ones, like in your Hampton Bay fan, hum more than others. There are some steps you can take to reduce the hum:
* If you are using the fan with a solid-state control (i.e. a dimmer), that will cause the fan to hum. These controls are dangerous when used with fans, and a fire can result. You should have a qualified person remove the switch immediately and replace it with either a regular on/off switch OR a discrete-speed (i.e. 3-speed or 4-speed, rather than variable-dimmer) switch. Specially-designed ceiling fan switches such as this are available at your local Home Depot or Lowes. You could also use a remote-control system.
* If you have a remote control or other speed control system, make sure that the pull-chain speed control on the fan is set to the "high" position (highest speed possible) and left there.
* Make sure that all the screws are tight -- this includes screws which hold up the fan's mounting bracket, hold the blades onto the fan, and hold any applicable glass onto the light kit.
* Even if you don't have a speed control, the motor will still produce an electrical hum -- and the blades, which are physically attached to the motor, serve as mechanical amplifiers -- they take the tiny electrical hum and amplify it just like the big brass funnel speaker on an antique gramophone (record player) takes the tiny vibrations of the needle on the record and amplifies them to a comfortably audible level. High-end fans have a rubber flywheel attached to the motor between the blade holders and the motor unit -- and since rubber doesn't transmit vibrations well, this effectively deadens the sound. Your fan doesn't have one of these, but you can effectively replicate the noise-dampening effect by putting rubber washers between where the blade holders touch the bottom of the motor AND between where the screws which hold the blade holders onto the motor, meet the blade holders themselves. This will completely remove the path along which the sound vibrations can flow to the blades, and thus your hum will stop.
I hope this helps you! If you have any other questions, or need clarification, please ask!