The invention provides a method of lubricating a compression-ignition internal combustion engine with a maximum laden mass over 2,700 kg comprising supplying to the engine a lubricating composition comprising: an oil of lubricating viscosity, a 300 TBN or higher alkaline earth metal sulphonate detergent having a metal ratio of 10 to 40, 0.1 wt % to 4 wt % of a borated polyisobutylene succinimide dispersant, wherein the polyisobutylene from which the borated polyisobutylene succinimide is derived has a number average molecular weight of 550 to 1150, and 0.1 wt % to 6 wt % of a polyisobutylene succinimide, wherein the polyisobutylene from which polyisobutylene succinimide is derived has a number average molecular weight of 1550 to 2500, 0 wt % to 0.2 wt % of a phenolic based detergent, wherein the total amount of soap delivered by the alkaline earth metal sulphonates (typically calcium sulphonate) is 0.4 to 1 wt % of the lubricating composition, and wherein the lubricating composition has a sulphated ash content of not more than 1.5 wt %.

The invention provides a method of lubricating a compression-ignition internal combustion engine with a maximum laden mass over 2,700 kg comprising supplying to the engine a lubricating composition comprising: an oil of lubricating viscosity, a 300 TBN or higher alkaline earth metal sulphonate detergent having a metal ratio of 10 to 40, 0.1 wt % to 4 wt % of a borated polyisobutylene succinimide dispersant, wherein the polyisobutylene from which the borated polyisobutylene succinimide is derived has a number average molecular weight of 550 to 1150, and 0.1 wt % to 6 wt % of a polyisobutylene succinimide, wherein the polyisobutylene from which polyisobutylene succinimide is derived has a number average molecular weight of 1550 to 2500, 0 wt % to 0.2 wt % of a phenolic based detergent, wherein the total amount of soap delivered by the alkaline earth metal sulphonates (typically calcium sulphonate) is 0.4 to 1 wt % of the lubricating composition, and wherein the lubricating composition has a sulphated ash content of not more than 1.5 wt %.

The present disclosure relates to lubricant additives such as dispersants and dispersant viscosity modifiers including acyl peptide grafted polymers and lubricating oil compositions comprising such additives. The disclosure also relates to the use of lubricant compositions comprising the additives herein for improving the soot or sludge handling characteristics of an engine lubricant composition and while minimizing the deterioration of engine's elastomer compatibility.

The present disclosure relates to lubricant additives such as dispersants and dispersant viscosity modifiers including acyl peptide grafted polymers and lubricating oil compositions comprising such additives. The disclosure also relates to the use of lubricant compositions comprising the additives herein for improving the soot or sludge handling characteristics of an engine lubricant composition and while minimizing the deterioration of engine's elastomer compatibility.

The present invention provides a lubricant composition comprising a base oil of lubricating viscosity, wherein the base oil comprises an ether base stock of formula (A) where: R.sub.a and R.sub.b are aliphatic hydrocarbyl groups and may be the different; the lubricant composition further comprising from 0.5 to 7% of total dispersant additive, by weight of the lubricant composition. In some embodiments, the ether base stock has the formula (1) where: R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are as defined herein. The lubricant composition may be used for lubricating a surface in an internal combustion engine as well as for improving the fuel economy performance and/or piston cleanliness performance of an engine and/or a vehicle, such as an automotive vehicle associated with an internal combustion engine.

##STR00001##

A lubricant composition of an oil of lubricating viscosity, an ashless condensation reaction product of an olefin polymer, having a number average molecular weight of 2,000 to 70,000, comprising carboxylic acid or equivalent functionality grafted onto the polymer backbone, with a monoamine or a polyamine often having a single primary amino group; a succinimide dispersant; and an overbased metal detergent, in an amount such that the total base number of the lubricant composition is less than 6.5, exhibits good sludge prevention performance in a gasoline engine.

The invention provides a lubricating composition containing an oil of lubricating viscosity and an ashless ketone compound with at least one of a hydroxy group and an ether linkage attached to the carbon atom adjacent to the carbonyl carbon of the ketone, especially -hydroxyketone. The invention further relates to methods of lubricating an internal combustion engine by supplying the described lubricating composition to the internal combustion engine. The invention further relates to the use of the -hydroxyketone compound as a friction modifier and an antiwear agent.

A lubricating oil composition contains: a base oil with a kinematic viscosity at 40 degrees C. in a range from 1 mm.sup.2/s to 200 mm.sup.2/s, a viscosity index of 80 or more and a sulfur content of less than 0.03 mass %; a component (A) being a polyacrylate compound with a mass average molecular weight in a range from 10,000 to 100,000; and a component (B) being at least one of phosphorus compounds represented by a formula (1) below. A content of the component (B) is in a range from 0.05 mass % to 2.0 mass % of a total amount of the composition, and a viscosity index of the composition is 160 or more. ##STR00001##

The present invention provides a refrigerating machine oil comprising at least one oxygen-containing oil having a carbon/oxygen molar ratio of 2.5 or more and 5.8 or less as a base oil, and the refrigerating machine oil being used with a trifluoroethylene refrigerant.

Disclosed is a lubricating oil composition which comprises: (a) a major amount of an oil of lubricating viscosity having a kinematic viscosity at 100 C. in a range of about 2 to about 50 mm.sup.2/s, (b) an overbased metal salt of an alkyl-substituted phenate detergent, wherein the alkyl group is derived from an isomerized normal alpha olefin having from about 10 to about 40 carbon atoms per molecule and having an isomerization level (I) of the normal alpha olefin of from about 0.1 to about 0.4 in an amount to provide at least 1000 ppm of calcium, (c) one or more magnesium-containing detergents having about 100 to about 1000 ppm of magnesium, based on the total weight of the lubricating oil composition, and (d) one or more zinc dialkyl dithiophosphate compounds derived from a primary alcohol.