The present invention provides a grease composition or a lubricating oil composition which is capable of effectively preventing hydrogen brittleness-caused peeling from occurring on a rolling surface of a rolling bearing, is excellent in durability in a high temperature and speed operation, and can be used for a long time. A grease-packed bearing (1) has an inner ring (2), an outer ring (3), and a plurality of rolling elements (4). A sealing member (6) for sealing a grease composition (7) is provided at openings (8a) and (8b) disposed at both axial ends of the inner ring (2) and the outer ring (3). The grease composition (7) includes a base grease composed of a base oil and a thickener and an additive added to the base grease. The additive contains at least one compound selected from among plant-derived polyphenolic compounds and compounds formed by decomposition thereof. The above-described compounds include tannin, gallic acid, ellagic acid, chlorogenic acid, caffeic acid, curcumin, quercetin, and quinic acid.

In one embodiment, a multidentate perfluoropolyether (PFPE) lubricant has the formula S.sub.e-S.sub.o-S.sub.i-S.sub.L-S.sub.i-S.sub.o-S.sub.e, where each S.sub.o includes at least one perfluoroethyl ether unit, S.sub.L is a linker segment, and each S.sub.e and S.sub.i include at least one functional group configured to attach to a surface. In another embodiment, a multi dentate PFPE lubricant has the formula S.sub.e-S.sub.o(a)-S.sub.i-S.sub.m-S.sub.i-S.sub.o(b)-S.sub.e, where each S.sub.o(a), S.sub.o(b), and S.sub.m include at least one perfluoroethyl ether unit with the proviso that S.sub.m has a different number of perfluoroethyl ether units than at least one of So.sub.(a) and S.sub.o(b), and each S.sub.e and S.sub.i include at least one functional group configured to attach to a surface.

The present invention relates to the field of lubricant, and specifically provides a lubricant composition and its preparation method and use. The lubricant composition comprises a base oil and rubber particles having radiation crosslinked structure dispersed therein, wherein the base oil is continuous phase and the rubber particles are dispersed phase. The viscosity of the lubricant composition of the present invention can be effectively adjusted as temperature changes. As compared with the lubricant composition comprising chemically crosslinked rubber particles, it has a lower viscosity at low temperatures and a higher viscosity at high temperatures, and has a relatively high viscosity index, which can meet the application requirements at the temperature above 200? C. In addition, the lubricant composition of the present invention also has excellent antiwear and friction-reducing properties.