The invention relates to the use of an alcohol of formula ROH (I), in which R is a linear or branched saturated alkyl group with 10 to 36 carbon atoms, in a lubricant composition to improve the cleanliness of a 4-stroke vehicle engine.

Polyalkyl(meth)acrylate based polymers which include straight chained C.sub.18-24 alkyl(meth)acrylates and have an average carbon number of 7.0 to 7.5 and a weight-average molecular weight of 300,000 g/mol or greater are a useful component for a lubricant composition. Furthermore, lubricant compositions containing such polymers show improved high temperature-high shear performance, especially in engine oil (EO) compositions.

A hydrocarbon fluid is disclosed that has a pour point of at most 30 C., as measured by ASTM D5950, and that comprises at least 99 wt % of naphthenes and paraffins, based on the total weight of the hydrocarbon fluid, wherein the weight ratio of naphthenes to paraffins is at least 1, as measured by GC-MS, and wherein the paraffins consist essentially of isoparaffins, as determined by GC-FID. In addition, preferred uses of said hydrocarbon fluid are disclosed.

A gear lubricant composition includes at least 97% by weight, based on the total weight of the lubricant composition, of at least one hydrocarbon-based oil that includes a weight content of isoparaffins ranging from 90 to 0%, a weight content of normal paraffins ranging from 0 to 10% and a carbon content of biological origin greater than or equal to 90% relative to the total weight of the oil, at least 0.01% by weight, based on the total weight of the lubricant composition, of at least one additive selected among the anti-wear additives, extreme pressure additives, anti-corrosion additives, additives having metal-deactivating properties, anti-foam additives, anti-oxidant additives selected among the phenolic anti-oxidants, and the mixtures thereof.

The invention provides a lubricating oil composition for diesel engines which contains a GTL base oil with a kinematic viscosity at 100 C. of 4.5 to 5.5 mm2/s, a comblike PMA (polymethacrylate) based viscosity index improver and a boron-containing dispersant and/or boron-containing detergent, the total content of the boron-containing dispersant and/or boron-containing detergent in terms of conversion to boron content relative to the total amount of the composition being not less than 0.025 mass %, and which satisfies 0W-30 or 5W-30 in the SAE J300 standard.

The invention provides a lubricating oil composition for diesel engines which contains a GTL base oil with a kinematic viscosity at 100 C. of 4.5 to 5.5 mm2/s, a comblike PMA (polymethacrylate) based viscosity index improver and a boron-containing dispersant and/or boron-containing detergent, the total content of the boron-containing dispersant and/or boron-containing detergent in terms of conversion to boron content relative to the total amount of the composition being not less than 0.025 mass %, and which satisfies 0W-30 or 5W-30 in the SAE J300 standard.

This lubricant base oil includes a condensation ester of an alcohol (A) and a carboxylic acid (B), wherein the alcohol (A) contains a polyhydric alcohol represented by general formula (1) (in formula (1), R.sup.1-R.sup.4 independently represent a hydrogen atom, a methyl group, or a hydroxyl group, and at least two of R.sup.1-R.sup.4 each represents a hydroxyl group), and the carboxylic acid (B) contains a C4-C8 cycloalkane monocarboxylic acid. The lubricant base oil has excellent heat resistance and lubricating property. ##STR00001##

A composition with a kinematic viscosity for cooling and lubricating a drive system of an electric or hybrid vehicle, measured at 100 C. in accordance with the standard ASTM D445, in the range 3 to 10 mm.sup.2/s. The composition includes 70% to 90% of a base oil or a mixture of base oils having a kinematic viscosity, measured at 100 C. in accordance with the standard ASTM D445, of 1.5 to 8 mm.sup.2/s and selected from polyalphaolefins; and at least one thickening polymer.

Disclosed is a lubricant base stock blend comprising a PAO base stock and an alkylated aromatics (AA) base stock, wherein at least the longer portion of the pendant groups attached to the carbon backbones of the PAO molecules have comparable length to at least the longer portion of the side chain groups attached to the aromatic ring structure of the AA molecules. The comparable lengths of at least the longer portion of the pendant groups and the side chain groups lead to enhanced improvement in oxidation stability of the blend.

In some embodiments, a compound has the formula (I) where: R.sub.1 and R.sub.2 are alkyl or, together with the carbon atom to which they are attached, cycloalkyl; R.sub.3, R.sub.4 and R.sub.5 are H or alkyl (formula II); R.sub.6 is alkyl or where: R.sub.7 and R.sub.8 are H, alkyl or, together with the carbon atom to which they are attached, cycloalkyl; R.sub.9 is H or alkyl; X is alkylene or is absent; and p is 0, 1, 2 or 3; and m and n are 0, 1, 2 or 3 provided that m is 0 when R.sub.4 and R.sub.5 are H. The compound is suitable for use as a base stock which provides low volatility for a given viscosity profile. The compound may be used in a lubricant composition for an internal combustion engine.

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