A viscosity index improver comprising a reaction product of (i) an acylated copolymer obtainable by acylating a copolymer of ethylene and one or more C.sub.3-C.sub.10 alpha-olefins having an Mn of 3,000 to 250,000 g/mol; and (ii) a compound of the formulae (III)-(V): ##STR00001##
wherein R.sub.6, R.sub.8, R.sub.9, R.sub.10, R.sub.12 and R.sub.15 are independently selected from a hydrogen and an optionally substituted linear or branched alkyl or alkenyl group, and R.sub.7, R.sub.11, R.sub.13, R.sub.14, R.sub.16, and R.sub.17 are independent selected from an optionally substituted linear or branched alkyl or alkenyl group, and a sum of the number of carbon atoms in each compound of the formulae (III)-(V) is from 6 to 31.

A viscosity index improver comprising a reaction product of (i) an acylated copolymer obtainable by acylating a copolymer of ethylene and one or more C.sub.3-C.sub.10 alpha-olefins having an Mn of 3,000 to 250,000 g/mol; and (ii) a compound of the formulae (III)-(V):

##STR00001##

wherein R.sub.6, R.sub.8, R.sub.9, R.sub.10, R.sub.12 and R.sub.15 are independently selected from a hydrogen and an optionally substituted linear or branched alkyl or alkenyl group, and R.sub.7, R.sub.11, R.sub.13, R.sub.14, R.sub.16, and R.sub.17 are independent selected from an optionally substituted linear or branched alkyl or alkenyl group, and a sum of the number of carbon atoms in each compound of the formulae (III)-(V) is from 6 to 31.

A viscosity index improver comprising a reaction product of (i) an acylated copolymer obtainable by acylating a copolymer of ethylene and one or more C.sub.3-C.sub.10 alpha-olefins having an Mn of 3,000 to 250,000 g/mol; and (ii) a compound of the formulae (III)-(V):

##STR00001##

wherein R.sub.6, R.sub.8, R.sub.9, R.sub.10, R.sub.12 and R.sub.15 are independently selected from a hydrogen and an optionally substituted linear or branched alkyl or alkenyl group, and R.sub.7, R.sub.11, R.sub.13, R.sub.14, R.sub.16, and R.sub.17 are independent selected from an optionally substituted linear or branched alkyl or alkenyl group, and a sum of the number of carbon atoms in each compound of the formulae (III)-(V) is from 6 to 31.

The present invention aims to provide a viscosity index improver composition capable of providing a lubricant composition that has an excellent viscosity index improving effect, excellent antifoaming properties, and excellent persistence of the antifoaming properties. The present invention relates to a viscosity index improver composition, containing: a (co)polymer (A) containing a monomer (a) represented by the following formula (1) as an essential monomer; a C18-C40 chain aliphatic alcohol (B); and a base oil,

##STR00001##

wherein R.sup.1 is a hydrogen atom or a methyl group; -X.sup.1- is a group represented by —O— or —NH—; R.sup.2 is a C2-C4 alkylene group; R.sup.3 and R.sup.4 are each independently a C8-C24 linear or branched alkyl group; and p is an integer of 0 to 20, with each R.sup.2 being optionally the same as or different from each other when p is 2 or greater.

The present invention aims to provide a viscosity index improver composition capable of providing a lubricant composition that has an excellent viscosity index improving effect, excellent antifoaming properties, and excellent persistence of the antifoaming properties. The present invention relates to a viscosity index improver composition, containing: a (co)polymer (A) containing a monomer (a) represented by the following formula (1) as an essential monomer; a C18-C40 chain aliphatic alcohol (B); and a base oil,

##STR00001##

wherein R.sup.1 is a hydrogen atom or a methyl group; -X.sup.1- is a group represented by —O— or —NH—; R.sup.2 is a C2-C4 alkylene group; R.sup.3 and R.sup.4 are each independently a C8-C24 linear or branched alkyl group; and p is an integer of 0 to 20, with each R.sup.2 being optionally the same as or different from each other when p is 2 or greater.

Disclosed are solvency enhancer compositions, for example, as additives to lubricating oils and as formulated in lubricating oil compositions and associated methods of preparation and use thereof. The compositions and methods can dissolve at least one of oxidation products and other organic polar compounds, due to lubricant degradation, formed and suspended in oil compositions including adding an effective amount of a solvency enhancer to the oils, wherein the solvency enhancer includes Guerbet alcohols. Further described are methods for dissolving organic deposits in an oil system including adding an effective amount of a solvency enhancer to the oil system, wherein the solvency enhancer includes Guerbet alcohols. Also provided are methods for preventing sludge and varnish formation in in-service oils including adding an effective amount of a solvency enhancer to the oils, wherein the solvency enhancer includes Guerbet alcohols.

Brine-tolerant lubricants are provided. The brine-tolerant lubricants may comprise an oil component, a surfactant component, and, optionally, an additive component. In one aspect, the oil component comprises a fatty acid alkyl ester. In one aspect, the surfactant component comprises at least one of an alkoxylated fatty acid and an alkoxylated fatty alcohol. Also provided are methods for increasing the lubricity of a drilling fluid by contacting the drilling fluid with the brine-tolerant lubricants.

Brine-tolerant lubricants are provided. The brine-tolerant lubricants may comprise an oil component, a surfactant component, and, optionally, an additive component. In one aspect, the oil component comprises a fatty acid alkyl ester. In one aspect, the surfactant component comprises at least one of an alkoxylated fatty acid and an alkoxylated fatty alcohol. Also provided are methods for increasing the lubricity of a drilling fluid by contacting the drilling fluid with the brine-tolerant lubricants.

A viscosity index improver comprising a reaction product of (i) an acylated copolymer obtainable by acylating a copolymer of ethylene and one or more C.sub.3-C.sub.10 alpha-olefins having an Mn of 3,000 to 250,000 g/mol; and (ii) a compound of the formulae (I)-(V): ##STR00001##
wherein R.sub.1, R.sub.6, R.sub.8, R.sub.9, R.sub.10, R.sub.12 and R.sub.15 are independently selected from a hydrogen and an optionally substituted linear or branched alkyl or alkenyl group, and R.sub.2, R.sub.3, R.sub.4, and R.sub.5 R.sub.7, R.sub.11, R.sub.13, R.sub.14, R.sub.16, and R.sub.17 are independent selected from an optionally substituted linear or branched alkyl or alkenyl group, and a sum of the number of carbon atoms in each compound of the formulae (I)-(V) is from 6 to 31.

A viscosity index improver comprising a reaction product of (i) an acylated copolymer obtainable by acylating a copolymer of ethylene and one or more C.sub.3-C.sub.10 alpha-olefins having an Mn of 3,000 to 250,000 g/mol; and (ii) a compound of the formulae (I)-(V): ##STR00001##
wherein R.sub.1, R.sub.6, R.sub.8, R.sub.9, R.sub.10, R.sub.12 and R.sub.15 are independently selected from a hydrogen and an optionally substituted linear or branched alkyl or alkenyl group, and R.sub.2, R.sub.3, R.sub.4, and R.sub.5 R.sub.7, R.sub.11, R.sub.13, R.sub.14, R.sub.16, and R.sub.17 are independent selected from an optionally substituted linear or branched alkyl or alkenyl group, and a sum of the number of carbon atoms in each compound of the formulae (I)-(V) is from 6 to 31.