At both ends "Tiny Cooling Fan" bearings are designed with oil ring and glue the lubricant to reduce friction and noise during the operation. However, when the high temperature gas thus generated also make operation, and can not be ruled out, both ends of the bearing ring is an oil and wheat it intercepted nitride formed solid, stuffed the gap between the shaft and the bearing core, thereby causing the entire Ma "Tiny Cooling Fan" is not smooth when running up to produce more noise. So this traditional hydraulic fan of life are probably about a year, and preferably about six months plus one-yourself oil. But it also has the advantage, "Tiny Cooling Fan" in terms of price is its biggest advantage, but also more resistant to external impact, relatively little damage during handling. Due to various shortcomings, hydraulic fan has started in the market disappeared.