Lubricant compositions comprising an oil of lubricating viscosity and a viscosity modifier that is a hydrocarbon polymer having a number average molecular weight (M.sub.n) of less than 10,000 Daltons (Da). The viscosity modifier is present at greater than 2 wt %, based on a total weight of the lubricant composition. Exemplary hydrocarbon polymers include, but are not limited to, olefin polymers, such as polyisobutylene polybutene, ethylene ?-olefin copolymers, or combinations thereof.

The invention provides an SRT material (lubricant) applicable to machine elements such as bearings, seals or guides (guiding mechanisms) that constitute a slide part of a machine. A lubricant and an SRT material are disclosed.

A PAO lubricant base stock having a KV100 of at least 200 cSt and comprising multiple PAO molecules comprising at least 200 carbon atoms per molecule, wherein each of the PAO molecules comprises multiple pendant groups; and the average pendant group length of all the pendant groups excluding one methyl on each of the PAO molecules among at least 90 mol % of all of the PAO molecules, if one or more methyl is present, is at least 6.0. The PAO base stock exhibits high EHL thicknesses at 40 C., 80 C., and 120 C., rendering it particularly useful in lubricant compositions experiencing high-stress events such as gear oils, automotive transmission oils, and the like.

The present invention addresses the problem of providing a lubricating oil composition having excellent heat resistance (suppression of discoloration in heating) and tackiness while maintaining excellent viscosity properties of a lubricating oil composition using a ricinolic acid polymer. The present invention provides a copolymer (B) containing structural units (a) derived from ricinolic acid, structural units (b) derived from an aliphatic dicarboxylic acid and structural units (c) derived from a diol having 2 to 10 carbon atoms in a specific ratio and having a specific intrinsic viscosity, and provides a lubricating oil composition containing a base oil and the copolymer (B) and having a mass ratio (mass of (A) /mass of (B)) of the base oil (A) to the copolymer (B) of 60/40 to 99.5/0.5.

A lubricant composition comprising a high-viscosity PAO lubricant base stock having a KV100 of at least 200 cSt and comprising multiple PAO molecules comprising at least 200 carbon atoms per molecule, wherein (i) each of the PAO molecules comprises multiple pendant groups; (i) the average pendant group length of all the pendant groups excluding one methyl on each of the PAO molecules among at least 90 mol % of all of the PAO molecules, if one or more methyl is present, is at least 6.0, and (iii) the concentration of the high-viscosity PAO base stock is no more than 75 wt % of the total weight of the lubricant composition. The lubricant composition exhibits provides a high degree of protection of gear surfaces as measured by ASTM D5182.

The presently disclosed technology relates to a nano-additives to improve the performance of lubricants, oils, and greases. More specifically, the presently disclosed technology relates to applying capped metal oxide nanoparticles, such as capped zirconia nanoparticles, in the lubricants to produce a tribofilms on the lubricating surfaces to provide wear protection to the said surfaces. Also, the interaction of the capped zirconia nanoparticles with other commonly used additives in lubricants may further optimize the performance of the resulting tribofilms.

A method of using lubricant compositions to reduce wear between two surfaces exposed to a load condition of at least 1 GPa is provided. The lubricant compositions comprise polysiloxane base oils having alkylaryl or a combination of alkyl and aryl functionality. The polysiloxane base oils may be defined according to the formula: ##STR00001##
wherein R, R, and R are independently selected, such that R is an alkyl group having between 1-3 carbon atoms; R is an alkylaryl group comprising alkyl functionality with 3-12 carbon atoms and aryl functionality with 6 to 12 carbon atoms; R is an alkyl group having between 1-3 carbon atoms or an alkylaryl group comprising alkyl functionality with 3-12 carbon atoms and aryl functionality with 6 to 12 carbon atoms; and m and n are integers, such that 8<(m+n)<500.

Method and System of lubricating at least one moving part with a medium. The medium includes a dissolved mixture of lubricant and compressed gas. The amount of lubricant and compressed gas may be controlled in forming the dissolved mixture in response to input conditions. A user and/or external factors may be used to determine the input conditions. In response to the input conditions the amount of lubricant and compressed gas is delivered to the moving part that is housed in a pressurized chamber. The properties of the dissolved mixture can be adjusted, whereby the properties may include, but are not limited to, the following: viscosity, temperature, and thermal conductivity. This adjustment to the gas may be accomplished, for example, by releasing gas from the pressurized chamber in an amount to adjust the properties. In a further approach, lubricant may be scavenged from the pressurized chamber by returning surplus lubricant to its original source or other designated location.

A PAO lubricant base stock having a KV100 of at least 200 cSt and comprising multiple PAO molecules comprising at least 200 carbon atoms per molecule, wherein each of the PAO molecules comprises multiple pendant groups; and the average pendant group length of all the pendant groups excluding one methyl on each of the PAO molecules among at least 90 mol % of all of the PAO molecules, if one or more methyl is present, is at least 6.0. The PAO base stock exhibits high EHL thicknesses at 40 C., 80 C., and 120 C., rendering it particularly useful in lubricant compositions experiencing high-stress events such as gear oils, automotive transmission oils, and the like.

A lubrication fluid including cyclic hydrocarbons in combination with dimethylsilicone fluids and/or di-alkyl or di-cycloalkyl or alkyl-cycloalkyl, or mixtures thereof, and di-end-capped polypropylene oxides or highly branched esters to produce very high traction elastohydrodynamic (EHD) traction fluids and to modify the low temperature viscometric properties of the mixed fluids without adversely affecting the very high elastohydrodynamic shear strength or traction coefficients of the very high shear strength cyclic hydrocarbon fluid in the resulting mixed fluids with improved low temperature viscosity.