A grease made by combining polychlorotrifluoroethylene oil with a thickening agent comprising polychlorotrifluoroethylene (PCTFE) polymer. The thickening agent is made by polymerizing chlorotrifluoroethylene [R-1113] in the presence of a telogen, which is 2,2-dichloro-1,1,1-trifluoroethane[R-123] or a homolog thereof, namely CF.sub.3 --CF.sub.2 --CHCl.sub.2, CF.sub.3 --CF.sub.2 --CF.sub.2 --CHCl.sub.2, and CF.sub.3 --CF.sub.2 --CF.sub.2 --CF.sub.2 --CHCl.sub.2.

There are provided a highly thermal conductive grease composition having both a thermal conductivity and a satisfactory dispense property, and a cooling device applied with same. The grease composition comprises from 70 to 90% by volume of an inorganic powder which is a mixture containing at least two kinds of inorganic powders different from each other in each average particle size, and from 10 to 30% by volume of a base oil containing a mineral oil or a synthetic oil, the base oil further containing a surfactant in an amount of from 0.2 to 2.0% by weight based on the weight of the inorganic powder.

The rolling device of the present invention utilizes any one of 1) a lubricant containing a liquid fluorinated polymer oil having a kinetic viscosity at -20.degree. C. falling within a range of between 100 mm.sup.2 /sec and 3,000 mm.sup.2 /sec and a vapor pressure at 50.degree. C. not higher than 2.times.10.sup.-4 Torr, 2) a lubricant containing a liquid fluorinated polymer oil having a kinetic viscosity at 40.degree. C. falling within a range of between 10 mm.sup.2 /sec and 400 mm.sup.2 /sec and having a kinetic viscosity at 100.degree. C. falling within a range of between 3 mm.sup.2 /sec and 80 mm.sup.2 /sec, and 3) a lubricant constituted by a grease composition containing a mixture of a liquid fluorinated polymer oil having a kinetic viscosity at 40.degree. C. falling within a range of between 10 mm.sup.2 /sec and 400 mm.sup.2 /sec as a base oil and a thickening agent.

A rolling bearing has a grease filled therein. The grease contains a perfluoropolyether oil having a straight-chain structure having a dynamic viscosity of from 40 to 160 mm.sup.2 /s, preferably from 40 to 100 mm.sup.2 /s, at 40.degree. C. as a base oil and a particulate fluororesin as a base oil, and a particulate polytetrafluoroethylene as a thickening agent.

This invention is to provide a conductive grease which is less to decrease conductivity as a time passes. The conductive grease comprises a base oil, a thickener, a conductive solid powder, and at least one kind of a wear inhibitor, an extreme pressure agent and an oiliness agent, wherein an amount of the conductive solid powder added is 0.1 to 10 wt %, and an amount of the at least one kind of a wear inhibitor, an extreme pressure agent and an oiliness agent added is 0.1 to 10 wt %. Further, the conductive grease comprises the base oil and at least one of conductive additives, and the conductive additives are fibrous carbon, metallic particle, metallic compound particle and carbon nano-tube. The conductive grease to be packed into the rolling bearing comprises conductive fine particles such as carbon black and has an oil separation degree of 2% or lower. A ball bearing to be favorably used at high temperature comprises an inner race and an outer race, and a plurality of balls freely rotating between both races, and the conductive grease packed into a space defined between both races and holding the plural balls therein, and the conductive grease comprises the base oil, a thickener comprising fluorine compound or silicone compound and 0.2 to 10 wt % of the carbon black.