Viscosity modifier for lubricating oil and lubricating oil composition

A lubricating oil composition comprising:

• (A) a lubricating oil base, and
• (B) an ethylene/α-olefin copolymer in an amount of 1 to 30% by weight, which copolymer is comprising:
• (i) ethylene,
• (ii) an α-olefin of 3 or more carbon atoms, and
• (iii) a higher α-olefin of 4 to 20 carbon atoms wherein the carbon number of (iii) is larger than that of (ii) by one or more, and
• the ethylene/α-olefin copolymer (B) has the following properties (b-1) and (b-2):
• (b-1) a content of ethylene (i) is in the range of 60 to 80% by weight, a content of the α-olefin of 3 or more carbon atoms (ii) is in the range of 15 to 39% by weight, and a content of the higher α-olefin of 4 to 20 carbon atoms (iii) is in the range of 0.1 to 20% by weight with the proviso that the sum is 100% by weight;
• and
• (b-2) a weight-average molecular weight (Mw) in terms of polystyrene as measured by GPC is between 80,000 and 400,000;
• and
• (b-3) the ethylene/α-olefin copolymer (B) has an intensity ratio D of Sαβ to Sαα (Sαβ/Sαα) determined by a 13C-NMR spectrum of 0.5 or below.

A lubricating oil composition comprising:

• (A) a lubricating oil base,
• (B) an ethylene/α-olefin copolymer in an amount of 0.1 to 5% by weight, which copolymer is comprising:
• (i) ethylene,
• (ii) an α-olefin of 3 or more carbon atoms, and
• (iii) a higher α-olefin of 4 to 20 carbon atoms wherein the carbon number of (iii) is larger than that of (ii) by one or more, and
• (C) a pour-point depressant in an amount of 0.05 to 5% by weight;
• wherein the ethylene/α-olefin copolymer (B) has the following properties (b-1) and (b-2):
• (b-1) a content of ethylene (i) is in the range of 60 to 80% by weight, a content of the α-olefin of 3 or more carbon atoms (ii) is in the range of 15 to 39% by weight, and a content of the higher α-olefin of 4 to 20 carbon atoms (iii) is in the range of 0.1 to 20% by weight with the proviso that the sum is 100% by weight;
• and
• (b-2) a weight-average molecular weight (Mw) in terms of polystyrene as measured by GPC is between 80,000 and 400,000;
• and
• (b-3) the ethylene/α-olefin copolymer (B) has an intensity ratio D of Sαβ to Sαα (Sαβ/Sαα) determined by a 13C-NMR spectrum of 0.5 or below.