Lubricating oil composition

A lubricating oil composition used for cooling of an electric motor and lubrication of a gear in an electric vehicle, the composition comprising:

• a lubricating base oil composed of a (A) mineral oil having the following characteristics (A1) to (A3) and/or a (B) synthetic oil having the following characteristics (B1) to (B3) and an (C) ethylene-α-olefin copolymer having the following characteristics (C1) to (C5), the composition having a kinematic viscosity at 100° C. of 4 to 10 mm2/s:
• (A1) a kinematic viscosity at 100° C. of 2 to 6 mm2/s;
• (A2) a viscosity index of 105 or more;
• (A3) a pour point of −5° C. or lower;
• (B1) a kinematic viscosity at 100° C. of 1 to 9 mm2/s;
• (B2) a viscosity index of 110 or more;
• (B3) a pour point of −30° C. or lower;
• (C1) an ethylene molar content rate within a range of 30 to 70 mol %;
• (C2) a kinematic viscosity at 100° C. of 10 to 5,000 mm2/s;
• (C3) a Hasen chromaticity of 30 or lower;
• (C4) a molecular weight distribution (Mw/Mn) of 2.5 or less in molecular weight obtained in terms of polystyrene, as measured by gel permeation chromatography (GPC);
• and
• (C5) a B value represented by the following formula [1] of 1.1 or more:
• B
• =
• P
• O
• ⁢
• E
• 2
• ⁢
• P
• O
• ·
• P
• E
• [
• 1
• ]
• wherein P represents a molar fraction of ethylene component, PO represents a molar fraction of α-olefin component, and POE represents a molar fraction of ethylene-α-olefin sequence in the total dyad sequence.