A lubricating oil composition containing a viscosity modifier having a low shear stability index

Abstract

The present disclosure describes a method for improving the fuel consumption of an engine. The method includes lubricating the engine with a lubricating oil composition comprising a) an oil of lubricating viscosity, and b) a viscosity modifier comprising an olefin copolymer or a diene copolymer or a homopolymer, the viscosity modifier having a shear stability index of 15 or less. The lubricating oil composition substantially does not contain a viscosity modifier other than the viscosity modifier of b).

Description

Technical Field

[0001] Inventors: Maryam Sepehr, David Morgan, Claire Chommeloux, Peter Kleijwegt, Sara Yue Zhang The present disclosure relates to a method for improving fuel economy by incorporating a low SSI viscosity modifier in a lubricating oil composition.

Background Art

[0002] Improving fuel economy is an important driving force in the development of advanced lubricating oil technologies. Generally, lubricants having lower viscosities over a variety of temperature and shear conditions provide better fuel economy due to the reduction of viscous drag. Viscosity modifiers or viscosity index improvers, particularly those having improved shear stability, help to adjust the rheological properties of engine oils to achieve better fuel economy in vehicles.

Summary of the Invention

[0003] The present disclosure relates to a method for improving the fuel economy of an engine, the method comprising lubricating the engine with a lubricating oil composition comprising a) an oil of lubricating viscosity and b) a viscosity modifier comprising an olefin copolymer or a diene copolymer or a homopolymer, the viscosity modifier having a shear stability index of 15 or less, and the lubricating oil composition substantially free of viscosity modifiers other than the viscosity modifier of b).

[0004] In another aspect, the present disclosure relates to a method for increasing the fuel economy of a diesel engine, the method comprising lubricating the diesel engine with a lubricating oil composition comprising a) an oil of lubricating viscosity and b) a viscosity modifier comprising an olefin copolymer or a diene copolymer or a homopolymer, the viscosity modifier having a shear stability index of 15 or less, and the lubricating oil composition substantially free of viscosity modifiers other than the viscosity modifier of b).

Mode for Carrying Out the Invention

[0005] As used herein, "polymer" has two or more same or different monomer units. "Homopolymer" is a polymer having the same monomer units. "Copolymer" is a polymer having two or more different monomer units from each other.

[0006] As used herein, the term "substituted" means that hydrogen is replaced by a heteroatom or a heteroatom-containing group. For example, "substituted hydrocarbyl" is a group composed of carbon and hydrogen, and at least one hydrogen is replaced by a heteroatom or a heteroatom-containing group.

[0007] As used herein, Mn is the number-average molecular weight, Mw is the weight-average molecular weight, Mz is the z-average molecular weight, wt.% is the weight percent, and mol% is the mole percent. The molecular weight distribution (MWD), also referred to as the polydispersity index (PDI), is defined as Mw divided by Mn. Unless otherwise specified, all molecular weight units (e.g., Mw, Mn, Mz) are in g / mol.

[0008] The shear stability index (SSI) refers to the resistance of a polymer to mechanical degradation (polymer coil breakage) under shear stress measured by ASTM D6278 or D7109. For example, an SSI of 50 means that the polymer loses 50% of the viscosity contributed to the lubricant before decomposition.

[0009] At least one previous study suggests that polymers with higher SSI are used to improve fuel economy at a certain HTHS150 (high temperature high shear viscosity at 150 °C) or KV100 (kinematic viscosity at 100 °C). US Publication No. 20130143782 claims that an increase in the ratio of high / low SSI polymers improves fuel economy. This can be expected considering the increased contribution of shear thinning with a higher SSI polymer content.

[0010] It has surprisingly been found in the present disclosure that a lubricating oil composition containing a low SSI viscosity modifier can improve the fuel efficiency of an internal combustion engine. This improvement can be verified or determined by measuring the increase in fuel efficiency (referred to as "fuel efficiency improvement") from standardized dynamometer tests such as the World Harmonized Transient Cycle or the Heavy-Duty Supplemental Emissions test.

[0011] The present disclosure relates to a low SSI viscosity modifier (or viscosity index improver) in a lubricating oil composition and / or a method of using such a lubricating oil composition. As used herein, the term "low SSI" or "low shear stability index" means an SSI value of 15 or less, such as 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 1 to 15, 1 to 14, 1 to 13, 1 to 12, 1 to 11, 1 to 10, 1 to 9, 1 to 8, 1 to 7, 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, 2 to 15, 2 to 14, 2 to 13, 2 to 12, 2 to 11, 2 to 10, 2 to 9, 2 to 8, 2 to 7, 2 to 6, 2 to 5, 2 to 4, 2 to 3, 3 to 15, 3 to 14, 3 to 13, 3 to 12, 3 to 11, 3 to 10, 3 to 9, 3 to 8, 3 to 7, 3 to 6, 3 to 5, 3 to 4, 4 to 15, 4 to 14, 4 to 13, 4 to 12, 4 to 11, 4 to 10, 4 to 9, 4 to 8, 4 to 7, 4 to 6, 4 to 5, 5 to 15, 5 to 14, 5 to 13, 5 to 12, 5 to 11, 5 to 10, 5 to 9, 5 to 8, 5 to 7, 5 to 6, 6 to 15, 6 to 14, 6 to 13, 6 to 12, 6 to 11, 6 to 10, 6 to 9, 6 to 8, 6 to 7, 7 to 15, 7 to 14, 7 to 13, 7 to 12, 7 to 11, 7 to 10, 7 to 9, 7 to 8, 8 to 15, 8 to 14, 8 to 13, 8 to 12, 8 to 11, 8 to 10, 8 to 9, 9 to 15, 9 to 14, 9 to 13, 9 to 12, 9 to 11, 9 to 10, 10 to 15, 10 to 14, 10 to 13, 10 to 12, 10 to 11, 11 to 15, 11 to 14, 11 to 13, 11 to 12, 12 to 15, 12 to 14, 12 to 13, 13 to 15, 13 to 14, or 14 to 15.

[0012] According to one embodiment, a method for improving fuel efficiency includes lubricating an internal combustion engine with a lubricating oil composition, the lubricating oil composition comprising: a) a major amount of an oil of lubricating viscosity; and b) a viscosity modifier comprising an olefin copolymer or a diene copolymer or a homopolymer (e.g., a hydrogenated diene polymer), the viscosity modifier having an SSI of 15 or less. Generally, the lubricating oil composition does not contain a viscosity modifier other than the viscosity modifier of b). In some embodiments, the lubricating oil composition contains less than 0.01 wt% of other viscosity modifiers. Examples of other viscosity modifiers include polyalkyl methacrylate (PMA) polymers.

[0013] Viscosity Modifier The viscosity modifiers of the present disclosure are low SSI polymers, and the viscosity modifiers are i) ethylene-propylene olefin copolymers, or ii) diene copolymers or homopolymers.

[0014] For the purposes of this specification and the appended claims, when a polymer is referred to as containing an olefin, the olefin in such a polymer is in the polymerized form of the olefin. For example, an ethylene-propylene olefin copolymer is a polymer made from olefin monomers (i.e., ethylene and propylene). In some embodiments, olefin polymers ( "polyolefins" or "polyolefin polymers"), such as polyalphaolefin polymers made from propylene or other C3+ alpha olefin monomers, may contain hydrocarbyl groups that are side chains from the polymer backbone chain.

[0015] In some embodiments, the viscosity modifiers of the present disclosure can be linear in shape. In some embodiments, viscosity modifiers compatible with the present disclosure can be star-shaped. In some embodiments, viscosity modifiers compatible with the present disclosure can be random copolymers in which the monomer residues are randomly positioned.

[0016] ​The term "linear" means that the viscosity modifier, if present, has little to no long-chain branching and has a g’vis value of about 0.97 or greater, such as about 0.98 or greater.

[0017] "Star" means that the viscosity modifier has a multifunctional center (e.g., a polyalkenyl binder nucleus) from which at least three polymer arms radiate. In some embodiments, each polymer arm can be chemically identical (homo-star). In some embodiments, each polymer arm is not chemically identical (hetero-arm star). In some embodiments, the polymer arms include linear copolymers or homopolymers. The star polymer can be hydrogenated to form a hydrogenated star polymer. A more detailed discussion of star polymers can be found in U.S. Pat. Nos. 4,116,917 and 4,141,847, which are incorporated herein by reference.

[0018] 1. Ethylene-propylene olefin copolymer According to one embodiment, the olefin copolymer is an ethylene-propylene olefin copolymer (OCP). Ethylene-propylene OCPs are generally produced by the polymerization of ethylene and propylene monomers.

[0019] The ethylene-propylene-based olefin copolymer has a weight average molecular weight (Mw) in the range of about 10,000 g / mol to 100,000 g / mol, for example, about 20,000 g / mol to 100,000 g / mol, 20,000 g / mol to 90,000 g / mol, 20,000 g / mol to 80,000 g / mol, 20,000 g / mol to 70,000 g / mol, 20,000 g / mol to 60,000 g / mol, 20,000 g / mol to 50,000 g / mol, 20,000 g / mol to 40,000 g / mol, 20,000 g / mol to 30,000 g / mol, 30,000 g / mol to 100,000 g / mol, 30,000 g / mol to 90,000 g / mol, 30,000 g / mol to 80,000 g / mol, 30,000 g / mol to 70,000 g / mol, 30,000 g / mol to 60,000 g / mol, 30,000 g / mol to 50,000 g / mol, 30,000 g / mol to 40,000 g / mol, 40,000 g / mol to 100,000 g / mol, 40,000 g / mol to 90,000 g / mol, 40,000 g / mol to 80,000 g / mol, 40,000 g / mol to 70,000 g / mol, 40,000 g / mol to 60,000 g / mol, 40,000 g / mol to 50,000 g / mol, 50,000 g / mol to 100,000 g / mol, 50,000 g / mol to 90,000 g / mol, 50,000 g / mol to 80,000 g / mol, 50,000 g / mol to 70,000 g / mol, 50,000 g / mol to 60,000 g / mol, 60,000 g / mol to 100,000 g / mol, 60,000 g / mol to 90,000 g / mol, 60,000 g / mol to 80,000 g / mol, 60,000 g / mol to 70,000 g / mol, 70,000 g / mol to 100,000 g / mol, 70,000 g / mol to 90,000 g / mol, 70,000 g / mol to 80,000 g / mol, 80,000 g / mol to 100,000 g / mol, 80,000 g / mol to 90,000 g / mol, or 90,000 g / mol to 100,000 g / mol.

[0020] In some preferred embodiments, the ethylene-propylene olefin copolymer has a weight average molecular weight (Mw) in the range of about 30,000 g / mol to 80,000 g / mol, such as 30,000 g / mol to 75,000 g / mol, 30,000 g / mol to 65,000 g / mol, 30,000 g / mol to 55,000 g / mol, 30,000 g / mol to 45,000 g / mol, 30,000 g / mol to 35,000 g / mol, 35,000 g / mol to 80,000 g / mol, 35,000 g / mol to 75,000 g / mol, 35,000 g / mol to 65,000 g / mol, 35,000 g / mol to 55,000 g / mol, 35,000 g / mol to 45,000 g / mol, 45,000 g / mol to 80,000 g / mol, 45,000 g / mol to 75,000 g / mol, 45,000 g / mol to 65,000 g / mol, 45,000 g / mol to 55,000 g / mol, 55,000 g / mol to 80,000 g / mol, 55,000 g / mol to 75,000 g / mol, 55,000 g / mol to 65,000 g / mol, 65,000 g / mol to 80,000 g / mol, 65,000 g / mol to 75,000 g / mol, or 75,000 g / mol to 80,000 g / mol.

[0021] In one embodiment, the ethylene-propylene copolymer is ethylene-based. According to one embodiment, the ethylene-based ethylene-propylene copolymer has a total ethylene content in the range of about 35 wt% to about 70 wt%, for example, about 35 wt% to about 65 wt%, about 35 wt% to about 60 wt%, about 35 wt% to about 55 wt%, about 35 wt% to about 50 wt%, about 35 wt% to about 45 wt%, about 35 wt% to about 40 wt%, about 40 wt% to about 70 wt%, about 40 wt% to about 65 wt%, about 40 wt% to about 60 wt%, about 40 wt% to about 55 wt%, about 40 wt% to about 50 wt%, about 40 wt% to about 45 wt%, about 45 wt% to about 70 wt%, about 45 wt% to about 65 wt%, about 45 wt% to about 60 wt%, about 45 wt% to about 55 wt%, about 45 wt% to about 50 wt%, about 50 wt% to about 70 wt%, about 50 wt% to about 65 wt%, about 50 wt% to about 60 wt%, about 50 wt% to about 55 wt%, about 55 wt% to about 70 wt%, about 55 wt% to about 65 wt%, about 55 wt% to about 60 wt%, about 60 wt% to about 70 wt%, about 60 wt% to about 65 wt%, about 65 wt% to about 70 wt% based on the total weight of the ethylene-based olefin copolymer. When the copolymer is said to have an "ethylene" content of 35 wt% to 70 wt%, it is understood that the monomer units in the copolymer are derived from ethylene during the polymerization reaction and the derived units are present at 35 wt% to 70 wt% based on the weight of the copolymer.

[0022] In another embodiment, the ethylene-propylene copolymer is propylene-based. According to another embodiment, the propylene-based ethylene-propylene copolymer is from about 1 wt% to about 20 wt%, such as from about 1 wt% to 19 wt%, from about 1 wt% to about 18 wt%, from about 1 wt% to about 17 wt%, from about 1 wt% to about 16 wt%, from about 1 wt% to about 15 wt%, from about 1 wt% to about 14 wt%, from about 1 wt% to about 13 wt%, from about 1 wt% to about 12 wt%, from about 1 wt% to about 11 wt%, from about 1 wt% to about 10 wt%, from about 1 wt% to about 9 wt%, from about 1 wt% to about 8 wt%, from about 1 wt% to about 7 wt%, from about 1 wt% to about 6 wt%, from about 1 wt% to about 5 wt%, from about 1 wt% to about 4 wt%, from about 1 wt% to about 3 wt%, from about 1 wt% to about 2 wt%, from about 2 wt% to about 19 wt%, from about 2 wt% to about 18 wt%, from about 2 wt% to about 17 wt%, from about 2 wt% to about 16 wt%, from about 2 wt% to about 15 wt%, from about 2 wt% to about 14 wt%, from about 2 wt% to about 13 wt%, from about 2 wt% to about 12 wt%, from about 2 wt% to about 11 wt%, from about 2 wt% to about 10 wt%, from about 2 wt% to about 9 wt%, from about 2 wt% to about 8 wt%, from about 2 wt% to about 7 wt%, from about 2 wt% to about 6 wt%, from about 2 wt% to about 5 wt%, from about 2 wt% to about 4 wt%, from about 2 wt% to about 3 wt%, from about 3 wt% to about 20 wt%, from about 3 wt% to about 19 wt%, from about 3 wt% to about 18 wt%, from about 3 wt% to about 17 wt%, from about 3 wt% to about 16 wt%, from about 3 wt% to about 15 wt%, from about 3 wt% to about 14 wt%, from about 3 wt% to about 13 wt%, from about 3 wt% to about 12 wt%, from about 3 wt% to about 11 wt%, from about 3 wt% to about 10 wt%, from about 3 wt% to about 10 wt%, from about 3 wt% to about 9 wt%, from about 3 wt% to about 8 wt%, from about 3 wt% to about 7 wt%, from about 3 wt% to about 6 wt%, from about 3 wt% to about 5 wt%, from about 3 wt% to about 4 wt%, from about 4 wt% to about 20 wt%, from about 4 wt% to about 19 wt%, from about 4 wt% to about 18 wt%, from about 4 wt% to about 17 wt%, from about 4 wt% to about 16 wt%, from about 4 wt% to about 15 wt%, from about 4 wt% to about 14 wt%, from about 4 wt% to about 13 wt%, from about 4 wt% to about 12 wt%, from about 4 wt% to about 11 wt%, from about 4 wt% to about 10 wt%, from about 4 wt% to about 9 wt%, from about 4 wt% to about 8 wt%, from about 4 wt% to about 7 wt%, from about 4 wt% to about 6 wt%, from about 4 wt% to about 5 wt%, from about 5 wt% to about 20 wt%, based on the total weight of the ethylene-based olefin copolymer.About 5 wt% to about 19 wt%, about 5 wt% to about 18 wt%, about 5 wt% to about 17 wt%, about 5 wt% to about 16 wt%, about 5 wt% to about 15 wt%, about 5 wt% to about 14 wt%, about 5 wt% to about 13 wt%, about 5 wt% to about 12 wt%, about 5 wt% to about 11 wt%, about 5 wt% to about 10 wt%, about 5 wt% to about 9 wt%, about 5 wt% to about 8 wt%, about 5 wt% to about 7 wt%, about 5 wt% to about 6 wt%, about 6 wt% to about 20 wt%, about 6 wt% to about 19 wt%, about 6 wt% to about 18 wt%, about 6 wt% to about 17 wt%, about 6 wt% to about 16 wt%, about 6 wt% to about 15 wt%, about 6 wt% to about 14 wt%, about 6 wt% to about 13 wt%, about 6 wt% to about 12 wt%, about 6 wt% to about 11 wt%, about 6 wt% to about 10 wt%, about 6 wt% to about 10 wt%, about 6 wt% to about 9 wt%, about 6 wt% to about 8 wt%, about 6 wt% to about 7 wt%, about 7 wt% to about 20 wt%, about 7 wt% to about 19 wt%, about 7 wt% to about 18 wt%, about 7 wt% to about 17 wt%, about 7 wt% to about 16 wt%, about 7 wt% to about 16 wt%, about 7 wt% to about 15 wt%, about 7 wt% to about 14 wt%, about 7 wt% to about 13 wt%, about 7 wt% to 12 wt%, about 7 wt% to about 11 wt%, about 7 wt% to about 10 wt%, about 7 wt% to about 9 wt%, about 7 wt% to about 8 wt%, about 8 wt% to about 20 wt%, about 8 wt% to about 19 wt%, about 8 wt% to about 18 wt%, about 8 wt% to about 17 wt%, about 8 wt% to about 16 wt%, about 8 wt% to about 15 wt%, about 8 wt% to about 14 wt%, about 8 wt% to about 13 wt%, about 8 wt% to about 12 wt%, about 8 wt% to about 12 wt%, about 8 wt% to about 11 wt%, about 8 wt% to about 10 wt%, about 8 wt% to about 9 wt%, about 9 wt% to about 20 wt%, about 9 wt% to about 19 wt%, about 9 wt% to about 18 wt%, about 9 wt% to about 17 wt%, about 9 wt% to about 16 wt%, about 9 wt% to about 15 wt%, about 9 wt% to about 14 wt%, about 9 wt% to about 13 wt%, about 9 wt% to about 12 wt%, about 9 wt% to about 11 wt%, about 9 wt% to about 10 wt%, about 10 wt% to about 20 wt%, about 10 wt% to about 19 wt%, about 10 wt% to about 18 wt%, about 10 wt% to about 17 wt%, about 10 wt% to about 16 wt%, about 10 wt% to about 16 wt%, about 10 wt% to about 15 wt%, about 10 wt% to about 14 wt%, about 10 wt% to about 13 wt%, about 10 wt% to about 12 wt%,Having a total ethylene content of from about 10 wt% to about 11 wt%, from about 11 wt% to about 20 wt%, from about 11 wt% to about 19 wt%, from about 11 wt% to about 18 wt%, from about 11 wt% to about 17 wt%, from about 11 wt% to about 16 wt%, from about 11 wt% to about 15 wt%, from about 11 wt% to about 14 wt%, from about 11 wt% to about 13 wt%, from about 11 wt% to about 12 wt%, from about 12 wt% to about 20 wt%, from about 12 wt% to about 19 wt%, from about 12 wt% to about 18 wt%, from about 12 wt% to about 17 wt%, from about 12 wt% to about 16 wt%, from about 12 wt% to about 15 wt%, from about 12 wt% to about 14 wt%, from about 12 wt% to about 13 wt%, from about 13 wt% to about 20 wt%, from about 13 wt% to about 19 wt%, from about 13 wt% to about 18 wt%, from about 13 wt% to about 17 wt%, from about 13 wt% to about 16 wt%, from about 13 wt% to about 15 wt%, from about 13 wt% to about 14 wt%, from about 14 wt% to about 20 wt%, from about 14 wt% to about 19 wt%, from about 14 wt% to about 18 wt%, from about 14 wt% to about 17 wt%, from about 14 wt% to about 16 wt%, from about 14 wt% to about 15 wt%, from about 15 wt% to about 20 wt%, from about 15 wt% to about 19 wt%, from about 15 wt% to about 18 wt%, from about 15 wt% to about 17 wt%, from about 15 wt% to about 16 wt%, from about 16 wt% to about 20 wt%, from about 16 wt% to about 19 wt%, from about 16 wt% to about 18 wt%, from about 16 wt% to about 18 wt%, from about 16 wt% to about 17 wt%, from about 17 wt% to about 20 wt%, from about 17 wt% to about 19 wt%, from about 17 wt% to about 18 wt%, from about 18 wt% to about 20 wt%, from about 18 wt% to about 19 wt%, or from about 19 wt% to about 20 wt%.

[0023] In some preferred embodiments, the propylene-based ethylene-propylene copolymer has an ethylene content in the range of 4 to 10 wt%. In some preferred embodiments, the propylene-based ethylene-propylene copolymer has an ethylene content in the range of 6.5 to 8.5 wt%.

[0024] The ethylene-propylene olefin copolymer can be prepared by any suitable polymerization process. For example, the polymerization can proceed in homogeneous, bulk, solution (including supercritical), slurry, and gas phase type reactions.

[0025] Solution polymerization means a polymerization process in which the monomer is dissolved in an inert solvent or a liquid polymerization medium such as the monomer(s) or a formulation thereof. Solution polymerization can be homogeneous. Homogeneous polymerization is a polymerization in which the polymer product is dissolved in the polymerization medium. Such a system is clear as described in J. Vladimir Oliveira, C. Dariva and J. C. Pinto, Ind. Eng. Chem. Res., 2000, Vol. 29, p. 4627. Bulk polymerization means a polymerization process in which the monomer and / or comonomer to be polymerized uses little or no inert solvent as a solvent or diluent. A small amount of inert solvent may be used as a carrier for the catalyst and scavenger. A bulk polymerization system contains less than about 25% by weight, for example less than about 10% by weight, for example less than about 1% by weight, for example about 0% by weight of an inert solvent or diluent.

[0026] In some embodiments, the polymerization process can be carried out in batch, semi-batch, or continuous mode. Further, the polymerization process can proceed in a system having a single reactor or multiple reactors (in series and / or parallel configuration).

[0027] Suitable diluents / solvents for overlap include non-coordinating inert liquids. Examples include straight-chain and branched-chain hydrocarbons such as isobutane, butane, pentane, isopentane, hexane, isohexane, heptane, octane, dodecane, and mixtures thereof; cyclic and cycloaliphatic hydrocarbons such as cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane, and mixtures thereof, for example, those commercially available (Isopar (trademark)); perhalogenated hydrocarbons such as perfluorinated C4-C10 alkanes, chlorobenzene, and aromatic and alkyl-substituted aromatic compounds such as benzene, toluene, mesitylene, and xylene. Suitable solvents also include liquid olefins that can act as monomers or comonomers, including ethylene, propylene, 1-butene, 1-hexene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-octene, 1-decene, and mixtures thereof. In at least one embodiment, aliphatic hydrocarbon solvents are solvents such as isobutane, butane, pentane, isopentane, hexane, isohexane, heptane, octane, dodecane, and mixtures thereof; cyclic and cycloaliphatic hydrocarbons such as cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane, and mixtures thereof are used as solvents. In at least one embodiment, the solvent is not aromatic, for example, the aromatic is present in the solvent at less than about 1 wt%, for example, less than about 0.5 wt%, for example, less than about 0 wt% based on the weight of the solvent.

[0028] Suitable polymerization can be carried out at any temperature and / or pressure suitable for obtaining the desired polymer. In at least one embodiment, the temperature and / or pressure is in the range of about 0 °C to about 300 °C, such as about 30 °C to about 200 °C, such as about 60 °C to about 195 °C, such as about 75 °C to about 190 °C, such as about 80 °C to about 100 °C, and about 0.35 MPa to about 1500 MPa, such as about 0.45 MPa to about 100 MPa, such as about 0.5 MPa to about 50 MPa, such as about 1.7 MPa to about 30 MPa. In at least one embodiment, the suitable execution time of the polymerization reaction is in the range of about 0 to about 250 minutes, such as up to about 300 minutes, such as about 0 to about 120 minutes, such as about 0 to about 10 minutes, such as about 0 to about 30 minutes.

[0029] In some embodiments, the olefin copolymer of the present disclosure is obtained by viscous crushing in order to controllably reduce the molecular weight. Viscous destruction typically involves an extruder and may involve a viscous breaker. This process is described, for example, in US Patent Publication No. 2021024789, and US Patents Nos. 3,697,429, 5,391,617, 6,753,381, 5,837,773, 5,068,047, which are incorporated herein by reference.

[0030] Additional monomer In some embodiments, the polymerization of the ethylene-propylene-based olefin copolymer may include at least one additional monomer. Suitable examples of at least one additional monomer include substituted or unsubstituted C2-C40 alpha-olefins such as C2-C20, C2-C15, C2-C10, C5-C40, C5-C20, C5-C10, C10-C40, C10-C20, or C10-C15 alpha-olefins. The C2-C40 olefin monomer can be linear, branched, or cyclic. The C2-C40 cyclic olefin can be strained or unstrained, monocyclic, or polycyclic, and optionally can contain heteroatoms and / or one or more functional groups.

[0031] Specific examples of additional monomers include butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, norbornene, norbornadiene, dicyclopentadiene, cyclopentene, cycloheptene, cyclooctene, cyclooctadiene (e.g., 1,5 - cyclooctadiene), cyclododecene, 7 - oxanorbornene, 7 - oxanorbornadiene, their substituted derivatives, and their isomers. Derivatives include, for example, 1 - hydroxy - 4 - cyclooctene, 1 - acetoxy - 4 - cyclooctene, 5 - methylcyclopentene, and dicyclopentadiene.

[0032] 2. Diene - based copolymer / homopolymer In some embodiments, the viscosity modifier is a diene - based homopolymer or copolymer. The copolymer can be derived from the polymerization of two or more conjugated diene monomers. The homopolymer can be derived from the polymerization of a single conjugated diene monomer. In some embodiments, the diene - based copolymer or homopolymer is at least partially or fully hydrogenated.

[0033] Conjugated diene monomers contain at least two double bonds positioned in a conjugated relationship such as 1,3 - relationship. Conjugated diene monomers compatible with the present disclosure include, for example, conjugated dienes containing 4 to 20 carbon atoms such as 1,3 - butadiene, isoprene, piperylene, 4 - methylpenta - 1,3 - diene, 2 - phenyl - 1,3 - butadiene, 3,4 - dimethyl - 1,3 - hexadiene, and 4,5 - diethyl - 1,3 - octadiene. In some embodiments, conjugated diene monomers can be incorporated in a configuration larger than one. For example, isoprene monomers can be incorporated as 1,4 - or 3,4 - units, or mixtures thereof. In some embodiments, the majority of isoprene is incorporated into the polymer as 1,4 units in amounts greater than about 60% by mass, more preferably greater than about 80% by mass such as about 80 - 100% by mass, and most preferably greater than about 90% by mass such as about 93 - 100% by mass.

[0034] Similarly, butadiene monomers can be incorporated as 1,2- or 1,4-units. In some embodiments, most of the butadiene is incorporated into the polymer as 1,4 units of at least about 70 wt%, such as at least about 75 wt%, at least about 80 wt%, at least about 85 wt%, at least about 90 wt%, etc., for example 95-100 wt%.

[0035] Linear diblock copolymer (styrene hydrogenated diene) In some embodiments, the viscosity modifier is a linear polymer such as a linear diblock copolymer.

[0036] Non-limiting examples of linear diblock copolymers are polymers comprising one block mainly derived from vinyl aromatic hydrocarbon monomers and another block mainly derived from one or more conjugated diene monomers. One example of this is styrene hydrogenated diene (sometimes referred to as "hydrogenated styrene diene"). Useful vinyl aromatic hydrocarbon monomers include, for example, those containing 8 to 16 carbon atoms such as styrene, alkyl-substituted styrene, alkoxy-substituted styrene, vinyl naphthalene, and alkyl-substituted vinyl naphthalene. The amount of vinyl aromatic content of the copolymer can be 5 wt% to 40 wt% of the copolymer.

[0037] Diblock copolymers generally have two distinct blocks, and each block is different from the adjacent block. For example, a diblock copolymer can include two homopolymer subunits linked by a covalent bond(s). In some cases, a diblock copolymer may require non-repeating subunits.

[0038] The diblock structure, inter alia, conforms to the following generalized formula. -(A) x -(B) y- wherein x and y are integers, and thus the diblock polymer has a molecular weight consistent with the disclosure herein. Non-limiting examples of diblock structures include: -A-A-B-B- or -A-A-B- or -A-B-B-, wherein A and B represent repeating units.

[0039] Linear copolymers compatible with the present disclosure can have a weight-average molecular weight in the range of 40,000 g / mol to 150,000 g / mol, such as 40,000 g / mol to 125,000 g / mol, 40,000 g / mol to 100,000 g / mol, 40,000 g / mol to 75,000 g / mol, 40,000 g / mol to 50,000 g / mol, 50,000 g / mol to 150,000 g / mol, 50,000 g / mol to 125,000 g / mol, 50,000 g / mol to 100,000 g / mol, 50,000 g / mol to 75,000 g / mol, 75,000 g / mol to 150,000 g / mol, 75,000 g / mol to 125,000 g / mol, 75,000 g / mol to 100,000 g / mol, 100,000 g / mol to 150,000 g / mol, 100,000 g / mol to 125,000 g / mol, 125,000 g / mol to 150,000 g / mol. The term "weight-average molecular weight" as used herein refers to the weight-average weight measured by gel permeation chromatography ("GPC") using polystyrene standards following hydrogenation.

[0040] In some preferred embodiments, the linear copolymer may have a weight average molecular weight in the range of 40,000 g / mol to 80,000 g / mol, such as 40,000 g / mol to 75,000 g / mol, 40,000 g / mol to 65,000 g / mol, 40,000 g / mol to 55,000 g / mol, 40,000 g / mol to 45,000 g / mol, 45,000 g / mol to 80,000 g / mol, 45,000 g / mol to 75,000 g / mol, 45,000 g / mol to 65,000 g / mol, 45,000 g / mol to 55,000 g / mol, 55,000 g / mol to 80,000 g / mol, 55,000 g / mol to 75,000 g / mol, 55,000 g / mol to 75,000 g / mol, 55,000 g / mol to 65,000 g / mol, 65,000 g / mol to 80,000 g / mol, or 65,000 g / mol to 75,000 g / mol.

[0041] Useful block copolymers include those prepared in bulk, suspension, solution or emulsion. Polymerization can be achieved using free radical, cationic and anionic reaction initiators, or polymerization catalysts, such as transition metal catalysts used in Ziegler-Natta and metallocene type (also referred to as "single site") catalysts.

[0042] Non-limiting examples of linear diblock copolymers include copolymers comprising a polystyrene block and a block derived from a conjugated diene monomer, such as isoprene, butadiene, or mixtures thereof. In some embodiments, the linear diblock copolymer may be at least partially hydrogenated.

[0043] In some embodiments, the block derived from the vinyl aromatic hydrocarbon monomer (e.g., styrene) in the linear diblock copolymer may be present in an amount of up to 35% by weight, such as up to 25% by weight, such as 5 - 25% by weight, based on the total weight of the linear diblock copolymer. In some embodiments, the block derived from the conjugated diene monomer is present in an amount greater than 65% by weight, more preferably at least 75% by weight, and most preferably 75 - 95% by weight, based on the total weight of the linear diblock copolymer.

[0044] Examples of commercially available styrene / hydrogenated diene linear diblock copolymers include Infineum SV140 (trademark), Infineum SV150 (trademark), and Infineum SV160 (trademark) available from Infineum USA L.P. and Infineum UK Ltd.; LZ (registered trademark) 7408A available from The Lubrizol Corporation, and Septon 1001 (trademark) and Septon 1020 (trademark) available from Kuraray Company of America (Kuraray Group). Suitable styrene / 1,3 - butadiene hydrogenated block copolymers are sold under the trade name Glissoviscal (trademark) by BASF.

[0045] Star - shaped polymer In some embodiments, the viscosity modifier of the present disclosure is star - shaped, and the star - shaped polymer is at least partially hydrogenated. In some embodiments, the star - shaped polymer comprises or is at least partially derived from the polymerization of one or more conjugated diene monomers. The star - shaped polymer comprises a plurality of arms extending from a central core. In some embodiments, the polymer arms comprise a diene - based copolymer or a homopolymer.

[0046] The arms of the star - shaped polymer can be homopolymers derived from the polymerization of a single conjugated diene monomer such as isoprene or 1,3 - butadiene.

[0047] Alternatively, the arms of the star polymer can be copolymers derived from the polymerization of two or more conjugated diene monomers such as isoprene and 1,3-butadiene copolymers, or copolymers essentially derived from the polymerization of one or more conjugated diene monomers and vinyl aromatic hydrocarbon monomers such as isoprene-styrene copolymers, butadiene-styrene copolymers, or isoprene-butadiene-styrene copolymers.

[0048] The arms of the star polymer can be formed via anionic polymerization to form a living polymer. Anionic polymerization has been confirmed to provide polymers with a narrow molecular weight distribution (Mw / Mn), such as a molecular weight distribution of less than about 1.2.

[0049] The star polymers useful for the practice of the present invention can have a weight average molecular weight of about 300,000 g / mol to 1,000,000 g / mol, for example, 300,000 g / mol to 900,000 g / mol, 300,000 g / mol to 800,000 g / mol, 300,000 g / mol to 700,000 g / mol, 300,000 g / mol to 600,000 g / mol, 300,000 g / mol to 500,000 g / mol, 300,000 g / mol to 400,000 g / mol, 400,000 g / mol to 1,000,000 g / mol, 400,000 g / mol to 900,000 g / mol, 400,000 g / mol to 800,000 g / mol, 400,000 g / mol to 700,000 g / mol, 400,000 g / mol to 600,000 g / mol, 400,000 g / mol to 500,000 g / mol, 500,000 g / mol to 1,000,000 g / mol, 500,000 g / mol to 900,000 g / mol, 500,000 g / mol to 800,000 g / mol, 500,000 g / mol to 700,000 g / mol, 500,000 g / mol to 600,000 g / mol, 600,000 g / mol to 1,000,000 g / mol, 600,000 g / mol to 900,000 g / mol, 600,000 g / mol to 800,000 g / mol, 600,000 g / mol to 700,000 g / mol, 700,000 g / mol to 1,000,000 g / mol, 700,000 g / mol to 900,000 g / mol, 700,000 g / mol to 800,000 g / mol, 800,000 g / mol to 1,000,000 g / mol, 800,000 g / mol to 900,000 g / mol, or 900,000 g / mol to 1,000,000 g / mol. The term "weight average molecular weight" as used herein refers to the weight average weight measured by gel permeation chromatography ("GPC") using a polystyrene standard following hydrogenation.

[0050] Hydrogenated star polymer Hydrogenation of the star polymer involves hydrogenating olefinic unsaturation. This process is generally known and is described, for example, in U.S. Patent No. 4,141,847, which is incorporated herein by reference.

[0051] The degree of hydrogenation can vary. In some embodiments, at least 80%, such as at least 85%, at least 90%, at least 95%, or at least 98% of the original olefinic unsaturation is hydrogenated.

[0052] Hydrogenation is typically carried out in a suitable inert solvent using a hydrogenation catalyst such as a copper or molybdenum compound and a noble metal compound.

[0053] Examples of commercially available styrene hydrogenated diene star polymers include Infineum SV200(trademark), Infineum SV250(trademark), Infineum SV260(trademark), Infineum SV270(trademark), Infineum SV300(trademark) available from Infineum USA L.P. and Infineum UK Ltd.; LZ(registered trademark)5994A available from The Lubrizol Corporation.

[0054] Lubricating oil composition The low SSI copolymers or homopolymers of the present disclosure may be useful as additives in lubricating oils. The concentration of the viscosity modifier in the lubricating oil composition can range from 0.01 to 5 wt% (e.g., 0.5 to 5 wt%, 0.5 to 4 wt%, 0.5 to 3 wt%, 0.5 to 2 wt%, 0.5 to 1 wt%, 1 to 5 wt%, 1 to 4 wt%, 1 to 3 wt%, 1 to 2 wt%, 2 to 5 wt%, 2 to 4 wt%, 2 to 3 wt%, 3 to 5 wt%, 3 to 4 wt%, 4 to 5 wt%, etc.) based on the total weight of the lubricating oil composition.

[0055] Lubricating viscosity oils (sometimes referred to as "base stocks" or "base oils") are the major liquid components of lubricating oils, to which additives and sometimes other oils are blended to produce, for example, the final lubricating oil (or lubricating oil composition). Base oils useful for making concentrates and for making lubricating oil compositions therefrom may be selected from natural (vegetable, animal, or mineral) and synthetic lubricating oils and mixtures thereof.

[0056] The definitions of base stocks and base oils in the present disclosure are the same as those provided in American Petroleum Institute (API) Publication 1509 Twenty-First Edition (February 2022). Group I base stocks contain less than 90% saturated sulfur and / or more than 0.03% sulfur and have a viscosity index of 80 or more and less than 120 using the test methods defined in Table E-1. Group II base stocks contain 90% or more saturated sulfur and 0.03% or less sulfur and have a viscosity index of 80 or more and less than 120 using the test methods defined in Table E-1. Group III base stocks contain 90% or more saturated sulfur and 0.03% or less sulfur and have a viscosity index of 120 or more using the test methods defined in Table E-1. Group IV base stocks are polyalphaolefins (PAOs). Group V base stocks include all other base stocks not included in Groups I, II, III, or IV.

[0057] Natural oils include animal oils, vegetable oils (e.g., castor oil and lard oil), and mineral oils. Animal and vegetable oils with favorable thermal oxidation stability can be used. Among natural oils, mineral oils are preferred. Mineral oils vary widely depending on, for example, whether they are paraffinic, naphthenic, or a mixture of paraffinic and naphthenic, depending on their crude product sources. Oils derived from coal or shale are also useful. Natural oils also vary depending on the methods used for their production and purification, e.g., their distillation range, and whether they are straight-run, cracked, hydrorefined, or solvent-extracted.

[0058] Synthetic oils include hydrocarbon oils. Examples of hydrocarbon oils include oils such as polymerized and copolymerized olefins (e.g., polybutylene, polypropylene, propylene isobutylene copolymer, ethylene-olefin copolymer, and ethylene-alpha olefin copolymer). Polyalpha-olefin (PAO) oil base stocks are commonly used synthetic hydrocarbon oils. As an example, C8-C 14 olefins, such as C8, C 10 , C 12 , C 14 olefins, or PAO derived from mixtures thereof may be utilized.

[0059] Other useful fluids for use as base oils preferably include non-conventional or non-traditional base stocks that have been catalytically treated or synthesized to provide high performance characteristics.

[0060] Non-conventional or off-color base materials / base oils include one or more mixtures of one or more base materials (s) derived from one or more gas-to-liquids (GTL) materials, as well as isomers / iso-dewaxed base materials (s) derived from natural waxes or waxy feedstocks, waxy feedstocks such as mineral oil and / or non-mineral oil of slack wax, natural waxes, and waxy base materials such as gas oil, bottoms fractions of waxy fuel hydrocracking units, waxy raffinates, hydrocrackates, pyrolyzates, or other wax-like materials obtained from minerals, mineral oils, or coal liquefaction or shale oil, and mixtures of such base materials.

[0061] The base oil for use in the lubricating oil composition of the present disclosure is any of various oils corresponding to API Group I, Group II, Group III, Group IV, and Group V oils, and mixtures thereof, with API Group II, Group III, Group IV, and Group V oils, and mixtures thereof being preferred, and Group III to Group V base oils being more preferred due to their excellent volatility, stability, viscosity, and detergency characteristics.

[0062] Typically, the base oil has a kinematic viscosity (ASTM D445) in the range of 1.4 to 20 mm 2 / s (e.g., 3 to 12 mm 2 / s, 4 to 10 mm 2 / s, or 4.5 to 8 mm 2 / s) at 100 °C.

[0063] This lubricating oil composition also contains conventional lubricant additives for imparting auxiliary functions to provide a finished lubricating oil composition in which these additives are dispersed or dissolved. For example, the lubricating oil composition can be formulated with antioxidants, dispersants such as ashless dispersants, antiwear agents, detergents such as metal detergents, rust inhibitors, deodorants, demulsifiers or emulsifiers, friction modifiers, metal deactivators, pour point depressants, viscosity modifiers, antifoaming or defoaming agents, cosolvents, package compatibilizers, corrosion inhibitors, dyes, extreme pressure agents, oiliness improvers, etc., and mixtures thereof. Various additives are known and commercially available. These additives, or similar compounds thereof, can be used in the preparation of the lubricating oil composition of the present invention by conventional blending procedures.

[0064] Each of the aforementioned additives, when used, is used in a functionally effective amount to impart the desired properties to the lubricating oil. Thus, for example, when the additive is an ashless dispersant, the functionally effective amount of this ashless dispersant is an amount sufficient to impart the desired dispersion characteristics to the lubricating oil. Generally, the concentration of each of these additives, when used, can be in the range of about 0.001 to about 20 wt%, e.g., about 0.01 to about 10 wt%, about 0.1 to about 5 wt%, and about 1 to about 4 wt%, unless otherwise specified.

[0065] When the lubricating oil containing the polymer composition is measured by ASTM D445, it can have a kinematic viscosity of at least 2 cSt (e.g., at least 3 cSt, at least 4 cSt, at least 6 cSt, at least 8 cSt, at least 10 cSt, at least 12 cSt, or at least 15 cSt) at 100 °C. Similarly, when the lubricating oil containing the polymer composition is measured by ASTM D445, it can have a kinematic viscosity of 200 cSt or less (e.g., 150 cSt or less, 100 cSt or less, 50 cSt or less, 40 cSt or less, 30 cSt or less, or even 20 cSt or less) at 40 °C.

[0066] In one embodiment, the lubricating oil composition of the present disclosure can be identified by the viscosity standards of the Society of Automotive Engineers (SAE) for automotive lubricants. As an example, the lubricating composition is identified by the SAE J300 standard, which is the viscosity classification of engine oil. The J300 viscosity grades of the present disclosure are summarized in Table A.

Table 1

[0067] When the lubricating oil composition contains one or more of the components discussed above, the additive(s) is formulated into the composition in an amount sufficient to perform its intended function. Typical amounts of such additives useful in the present invention are shown in Table B below.

Table 2

Examples

[0068] The lubricating oil containing the low SSI viscosity modifier was tested for fuel consumption performance and compared with the lubricating oil containing the high SSI viscosity modifier.

[0069] The following Tables 1 and 2 summarize the content of Comparative Examples 1 - 3 and Inventive Examples 1 - 5, as well as the results of fuel consumption tests using three different engines. The fuel economy improvement (FEI) relative to the baseline oil (sometimes referred to as the "reference oil") is calculated using the fuel consumption or specific fuel consumption measured for each example or comparative example. The baseline oil was used to eliminate the influence of drift within the engine during the test.

[0070] Each sample contains a viscosity modifier in the form of Polymer A, B, C, D, E, or F as defined herein. Polymer A: An ethylene-based ethylene-propylene copolymer with 24 SSI and an Mw of approximately 83,000 g / mol Polymer B: An ethylene-based ethylene-propylene copolymer with 24 SSI and an Mw of approximately 135,000 g / mol Polymer C: An SSI propylene-based ethylene-propylene copolymer with 13 SSI and an Mw of approximately 63,000 g / mol Polymer D: A propylene-based ethylene-propylene copolymer with 8 SSI and an Mw of approximately 53,000 g / mol Polymer E: An SSI ethylene-based ethylene-propylene copolymer with 6 SSI and an Mw of approximately 44,000 g / mol obtained by viscous breakdown Polymer F: A star-shaped hydrogenated isoprene polymer with 5 SSI and an Mw of approximately 500,000 g / mol (commercially available as SV 200)

[0071] Referring to Table 1, the comparative and inventive examples contain 17.06% additive package, 0.3 wt% pour point depressant, and the remaining GrIII / IV base oil to make a 0W-20 oil. The oil is formulated to the same HTHS 150°C of 2.6 cP. These SAE 0W-20 oils were tested in two different engines equipped with a modal drive cycle and a transient drive cycle representing hydrodynamic, mixed, and boundary conditions.

[0072] DD13 Fuel Consumption Test (Modal Mode) The fuel consumption test in DD13 modal mode is an engine dynamometer test introduced by the U.S. Environmental Protection Agency (EPA) and described in the Supplemental Emissions Test (SET) for heavy-duty vehicles, which quantifies the fuel consumption benefits of the engine over a given test cycle. The standard test cycle consists of 13 individual modes (i.e., specific engine loads and RPMs) that are run for 7 minutes to stabilize temperature and pressure at a high level of consistency. This cycle is repeated a total of 8 times, and the last 7 times are used for the statistical evaluation of the operation. The flash process between lubricants ensures that no carry-over occurs. The test fixture is an improved Detroit Diesel DD13 engine. The FEI results are given as the percentage improvement in fuel consumption between the baseline oil (SAE10W-30) and the candidate lubricant. A weighting factor B (developed considering the deceleration tendency of large engines) is used.

[0073] OM501LA Fuel Consumption Test (WHTC) The OM501LA FE test is a World Harmonized Test Cycle (WHTC) test using the OM501LA Daimler engine. The WHTC test is a transient engine dynamometer schedule defined by the proposed International Technical Regulation (GTR) developed by the United Nations Economic Commission for Europe (UNECE) Pollution and Energy Reporting Conference (GRPE). The test procedure for WHTC can be verified in Section 4 of the GTR.

[0074] A transient test cycle (WHTC) with two representative test cycles, both cold start requirements and hot start requirements, has been created to cover typical driving conditions in the EU, the United States, Japan, and Australia. The WHTC test requirements were first adopted by the Euro VI exhaust gas regulations for large engines.

[0075] The WHTC is a 1800 - second transient test with several motoring intervals. The test procedure consists of a cold - start test after natural or forced cooling of the engine, a hot - soak period, and a hot - start test. The FEI results are given as the percentage improvement in fuel consumption between the baseline oil (SAE10W - 40) and the candidate lubricant.

Table 3

[0076] OM471 Fuel Consumption Test (WHTC) The OM471 FE test is a World Harmonized Test Cycle (WHTC) test using the OM471 Daimler engine. The WHTC test is a transient engine dynamometer schedule defined by the proposed International Technical Regulation (GTR) established by the United Nations Economic Commission for Europe (UNECE) Working Party on Pollution and Energy (GRPE). The test procedure of the WHTC can be verified in Section 4 of the GTR.

[0077] A transient test cycle (WHTC) with two representative test cycles, covering both cold - start requirements and hot - start requirements, has been created to cover typical driving conditions in the EU, the United States, Japan, and Australia. The WHTC test requirements were first adopted by the Euro VI exhaust gas regulations for large engines.

[0078] The WHTC is a 1800 - second transient test with several motoring intervals. The test procedure consists of a cold - start test after natural or forced cooling of the engine, a hot - soak period, and a hot - start test. The FEI results are given as the percentage improvement in fuel consumption between the baseline oil (SAE10W - 30) and the candidate lubricant.

Table 4

[0079] Overall, the fuel economy improvement (FEI) of the examples fabricated with VMs having low SSI shows distinct advantages compared to the comparative examples with higher SSI VMs.

[0080] All documents described herein are incorporated herein by reference and include any priority documents and / or test procedures, provided they do not conflict with the text. As is apparent from the foregoing general description and the specific embodiments, although multiple forms of the present disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, it is not intended that the present disclosure be limited thereby.

[0081] For the sake of brevity, only specific ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to enumerate ranges not explicitly described, and similarly, ranges from any lower limit may be combined with other arbitrary lower limits to enumerate ranges not explicitly described, and similarly, ranges from any upper limit may be combined with other arbitrary upper limits to enumerate ranges not explicitly described. Additionally, within a range, all points or individual values between its endpoints are included even if not explicitly enumerated. Thus, all points or individual values may be combined with other points or individual values, or other lower or upper limits, to function as their own lower or upper limits and enumerate ranges not explicitly described.

[0082] Unless otherwise specified, the phrases "consists essentially of" and "consisting essentially of" do not exclude the presence of other steps, elements, or materials, whether or not specifically described herein, as long as such steps, elements, or materials do not affect the basic and novel features of the present disclosure, and additionally, they do not exclude impurities and variations associated with the elements and materials normally used.

[0083] Similarly, the term "comprising" is considered to be synonymous with the term "including". Similarly, whenever there is a transitional phrase "comprising" before a composition, element, or group of elements, it is always understood that the same composition or group of elements with a transitional phrase "consisting essentially of", "consisting of", "selected from the group consisting of", or "being" before the description of that composition or element(s) is also contemplated, and vice versa.

[0084] As used herein, the terms "a" and "the" are understood to include not only the singular but also the plural forms.

[0085] Various terms are defined above. To the extent that a term used in a claim is not defined above, the broadest definition given to that term by one of ordinary skill in the art, as reflected in at least one printed publication or issued patent, should be given. Further, all patents, test procedures, and other documents cited in this application are hereby incorporated by reference in their entirety to the extent such disclosure is not inconsistent with this application and in all jurisdictions in which such incorporation is permitted.

[0086] The foregoing description of the present disclosure is illustrative and explanatory thereof. In addition, while the present disclosure shows and describes only preferred embodiments, as noted above, the present disclosure is usable in various other combinations, modifications, and environments and is capable of changes or modifications within the scope of the concepts expressed herein and commensurate with the above teachings and / or the skill or knowledge of the relevant art. It is to be understood that the foregoing relates to embodiments of the present disclosure, but other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, which is determined by the following claims.

[0087] The above embodiments describe the best mode known for practicing them and are further intended to enable one of ordinary skill in the art to utilize the present disclosure with such embodiments or other embodiments, with various modifications required by a particular application or use. Accordingly, the description is not intended to limit it to the forms disclosed herein. Also, the appended claims are intended to be construed to include alternative embodiments.

Claims

1. 1. A method for improving fuel economy of an engine, said method comprising: lubricating the engine with a lubricating oil composition, wherein the lubricating oil composition comprises: a) an oil of lubricating viscosity; b) a viscosity modifier comprising a diene-based copolymer or homopolymer, said viscosity modifier having a shear stability index of 15 or less; The method as described above, wherein the lubricating oil composition is substantially free of viscosity modifiers other than the viscosity modifier in b).

2. 10. The method of claim 1, wherein the lubricating oil composition is substantially free of polyalkyl methacrylate (PMA) viscosity modifiers.

3. The method of claim 1 , wherein the viscosity modifier is linear or star-shaped.

4. 4. The method of claim 3, wherein the star-shaped diene polymer has a weight average molecular weight of about 300,000 g / mol to 1,000,000 g / mol.

5. The method of claim 1 , wherein the diene-based copolymer or homopolymer is hydrogenated.

6. 10. The method of claim 1, wherein the viscosity modifier is a styrene hydrogenated diene copolymer.

7. 10. The method of claim 1, wherein the improvement in fuel economy is determined according to fuel economy improvement (FEI) as measured from a World Harmonized Transient Cycle or a Heavy-Duty Supplemental Emissions Test modal mode dynamometer test.

8. 1. A method for increasing fuel economy in a diesel engine, said method comprising: lubricating the diesel engine with a lubricating oil composition, wherein the lubricating oil composition comprises: a) an oil of lubricating viscosity; b) a viscosity modifier comprising a diene-based copolymer or homopolymer, said viscosity modifier having a shear stability index of 15 or less; The method as described above, wherein the lubricating oil composition is substantially free of viscosity modifiers other than the viscosity modifier in b).

9. 9. The method of claim 8, wherein the lubricating oil composition is substantially free of polyalkyl methacrylate (PMA) viscosity modifiers.

10. 9. The method of claim 8, wherein the viscosity modifier is linear or star-shaped.

11. 9. The method of claim 8, wherein the hydrogenated diene polymer has a weight average molecular weight of about 300,000 g / mol to 1,000,000 g / mol.

12. 9. The method of claim 8, wherein the hydrogenated diene polymer is a styrene hydrogenated diene copolymer.

13. 9. The method of claim 8, wherein the fuel economy improvement is determined according to fuel economy improvement (FEI) as measured from a Worldwide Harmonized Test Cycle or Heavy Vehicle Supplemental Emissions Test Modal Mode Dynamometer Test.