cleaning graphic card fans

[Yuri77]

i have Sapphire HD 7950 Dual X and i clean it every month but i need to know if i can dismantle the cooling fans and use white grease or sewing machine oil to lubricate the bearings ?
or the fans will be damaged if do this ?

Note : i use air blower to clean my computer - is this the reason for my graphic card fans to produce high sound when it reach above 60 degrees Celsius ?

http://i1318.photobucket.com/albums/t644/Yuri0077/vga_zpsczvet2tl.jpg

 

[Ximerous]

What bearing is are the fans and make sure their bearing aren't broke.