Grease composition and process for producing the same

A grease composition, which comprises a mixture of mutually incompatible thickener-containing non-fluorine-based base oil and thickener-containing fluorine-based base oil, the base oils being in a morphological structure, where one of the base oils is homogeneously dispersed in a particulate state in the other base oil, can be produced by kneading the mixture through a three-roll mill at least twice. By forming a morphological structure, one of the mutually incompatible non-fluorine-based base oil and fluorine-based base oil is homogeneously dispersed in a particulate state in the other base oil, that is, by forming a microscopically dispersed state, the following effects can be obtained: (1) less oil separation (smaller degree of oil separation) at elevated temperatures, (2) distinguished shearing stability, (3) low and stable friction coefficient, and (4) less abrasion.