A lubricating grease composition includes a base oil, a thickener, and a solid lubricant, wherein the base oil is a synthetic hydrocarbon oil with a kinematic viscosity of 600 to 2000 mm.sup.2/s at 40 C., the thickener is a barium complex soap, and the solid lubricant is an inorganic fine particle with Mohs hardness of 3 to 6 and an average particle size of 10 to 40 m.

The invention provides a lubricating grease composition comprising an oil of lubricating viscosity, a metallic soap thickener and a boron-containing compound, wherein the boron containing compound comprises a borate ester comprising at least one alkyl group having a branch at the position or higher. The invention further relates to a method of lubricating a mechanical device with the lubricant composition.

The invention provides a lubricating grease composition comprising an oil of lubricating viscosity, a metallic soap thickener and a boron-containing compound, wherein the boron containing compound comprises a borate ester comprising at least one alkyl group having a branch at the position or higher. The invention further relates to a method of lubricating a mechanical device with the lubricant composition.

The present invention provides a mineral base oil having a kinetic viscosity at 100 C. of 7 mm.sup.2/s or more and less than 10 mm.sup.2/s, a viscosity index of 100 or more, and a temperature gradient |*| complex viscosity between two temperature points of 5 C. and 15 C. of 240 mPa.Math.s/ C. or less as measured with a rotary rheometer at an angular velocity of 6.3 rad/s. The use of the mineral base oil enables easy preparation of a lubricating oil composition and a grease composition having excellent oxidation stability while ensuring the freedom of selection of additives.

The present invention provides a mineral base oil having a kinetic viscosity at 100 C. of 7 mm.sup.2/s or more and less than 10 mm.sup.2/s, a viscosity index of 100 or more, and a temperature gradient |*| complex viscosity between two temperature points of 5 C. and 15 C. of 240 mPa.Math.s/ C. or less as measured with a rotary rheometer at an angular velocity of 6.3 rad/s. The use of the mineral base oil enables easy preparation of a lubricating oil composition and a grease composition having excellent oxidation stability while ensuring the freedom of selection of additives.

This disclosure relates to a continuous process for preparing a grease thickener product in which operating conditions of the continuous process can be varied to obtain desired grease product properties. The process includes: (a) introducing a C.sub.3 to C.sub.30 hydroxy fatty acid or a C.sub.3 to C.sub.30 hydroxy fatty acid ester, and a metal base into a reaction zone; (b) operating the reaction zone at a temperature between 100 C. and 240 C. to react the C.sub.3 to C.sub.30 hydroxy fatty acid or the C.sub.3 to C.sub.30 hydroxy fatty acid ester, and the metal base, to produce a grease thickener product; (c) introducing the grease thickener product of step (b) into a flash chamber zone; and (d) operating the flash chamber zone at a temperature sufficient to remove volatiles from the grease thickener product of step (b). The continuous process conditions afford a production throughput of grease thickener product of greater than 8,000 pounds per hour.

This disclosure relates to a continuous process for preparing a grease thickener product in which operating conditions of the continuous process can be varied to obtain desired grease product properties. The process includes: (a) introducing a C.sub.3 to C.sub.30 hydroxy fatty acid or a C.sub.3 to C.sub.30 hydroxy fatty acid ester, and a metal base into a reaction zone; (b) operating the reaction zone at a temperature between 100 C. and 240 C. to react the C.sub.3 to C.sub.30 hydroxy fatty acid or the C.sub.3 to C.sub.30 hydroxy fatty acid ester, and the metal base, to produce a grease thickener product; (c) introducing the grease thickener product of step (b) into a flash chamber zone; and (d) operating the flash chamber zone at a temperature sufficient to remove volatiles from the grease thickener product of step (b). The continuous process conditions afford a production throughput of grease thickener product of greater than 8,000 pounds per hour.

Provided herein are grease compositions comprising at least one estolide compound of formula: ##STR00001##
in which n is an integer equal to or greater than 0; m is an integer equal to or greater than 2; R.sub.1, independently for each occurrence, is selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; R.sub.2 is selected from hydrogen and optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; and R.sub.3 and R.sub.4, independently for each occurrence, are selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched. Also provided are methods of making estolide-based grease products.

Provided herein are grease compositions comprising at least one estolide compound of formula: ##STR00001##
in which n is an integer equal to or greater than 0; m is an integer equal to or greater than 2; R.sub.1, independently for each occurrence, is selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; R.sub.2 is selected from hydrogen and optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; and R.sub.3 and R.sub.4, independently for each occurrence, are selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched. Also provided are methods of making estolide-based grease products.

A lubricant composition of an oil of lubricating viscosity and a phosphite ester reaction product of a monomeric phosphorous acid or an ester thereof with a first alkylene diol having two hydroxy groups in a 1,4 or 1,5 or 1,6 relationship and a second, alkyl-substituted, diol being a substituted 1,3-propylene diol, exhibits good wear and frictional performance.