"Waterproof Cooling Fan" is the use of oil-bearing sliding friction sleeve bearings, use lubricating oil as a lubricant and DRA. Use over time, due to the oil seal, oil will gradually volatile, and the dust will enter the bearing, causing "Waterproof Cooling Fan" slow speed, noise increases and other issues. Many manufacturers are the basis of a number of improvements in order to achieve better results change the frictional ball bearing rolling friction, this approach is more effective in reducing the friction between the bearing surface phenomenon, effectively raising the "Waterproof Cooling Fan" bearing life, and thus extend the life of the radiator. The disadvantage is that the process brings more complex, resulting in cost increase, it also brings higher operating noise.