Patent ID: 8183191

Claim:
A grease composition containing a lubricant base oil, diurea compounds represented by the following general formulas (1) to (3), an ester of paraffin oxide having a total acid number of 0.2-65 mgKOH/g and at least one phosphite ester selected from phosphite diesters; wherein respective contents of the diurea compounds represented by the following general formulas (1) to (3) satisfy conditions defined by the following expressions (4) and (5); and wherein the total content of the ester of pamraffin oxide and the phosphite ester is not greater than 4.5 mass %, the content of the ester of paraffin oxide is at least the 1 mass %, and the content of the phosphite ester is 0.5 mass % to 1.0 mass % based on the total amount of the grease composition: where R 1 is a hydrocarbon group containing an aromatic ring, R 2 is a divalent hydrocarbon group, and R 3 is a hydrocarbon group containing an aliphatic ring; 10≦ W 1 +W 2 +W 3 ≦20 (4) 0.3≦( W 1 +0.5 ×W 2 )/( W 1 +W 2 W 3 )≦0.7 (5) where W 1 , W 2 , and W 3 are respective contents (mass %) of the diurea compounds represented by general formulas (1) to (3) based on the total amount of the grease composition.