A method of reducing low-speed pre-ignition (LSPI) in a direct-injected spark-ignited internal combustion engine comprising lubricating the crankcase of the engine with a composition comprising a combination of a molybdenum-containing additive and a boron-containing additive. Preferably, the composition comprises a calcium detergent providing a calcium content of at least 0.08 wt %, based on the weight of the lubricating oil composition.

An ashless lubricating oil having a lubricating oil base stock as a major component, and a mixture of (i) at least one ashless antiwear additive, (ii) at least one ashless detergent, and (iii) at least one aminic antioxidant, as minor components. The lubricating oil base stock is a monoester obtained by a) reacting one Guerbet alcohol of 8 to 20 carbon atoms with a Guerbet acid, a linear or branched acid of 6 to 20 carbon atoms or b) reacting one linear or branched alcohol with at least 6 to 20 carbon atoms with a Guerbet acid of 8 to 20 carbon atoms. The lubricating oil base stock is present in an amount from 30 to 99.8 wt. % of the oil. A method for improving oxidative stability and high temperature stability of a lubricating oil in an engine or other mechanical component lubricated with the lubricating oil by using the ashless lubricating oil.

An ashless lubricating oil having a lubricating oil base stock as a major component, and a mixture of (i) at least one ashless antiwear additive, (ii) at least one ashless detergent, and (iii) at least one aminic antioxidant, as minor components. The lubricating oil base stock is a branched polyol ester. The lubricating oil base stock is present in an amount from about 30 to about 99.8 mass percent, based on the total mass of the ashless lubricating oil. A method for improving oxidative stability and high temperature stability of a lubricating oil in an engine or other mechanical component lubricated with the lubricating oil by using the ashless lubricating oil. The ashless lubricating oil is useful as a passenger vehicle engine oil (PVEO).

An organophosphorus compound has a structure represented by the general formula (I): ##STR00001## The functional groups are defined in the description. The organophosphorus compound has prominent bearing capacity and excellent antiwear and antifriction performances, and can be used as an extreme pressure antiwear additive and used in lubricating oil and lubricating grease.

A lubricant composition for a compression-ignition internal combustion engine comprises: (i) an amine as an ashless fuel additive having a total base number (TBN) of from about 275 to about 600 mg KOH/g when tested according to ASTM D2896; and (ii) a detergent selected from metal sulfonates, phenates, salicylates, carboxylates, thiophosphonates, and combinations thereof. The lubricant composition has a TBN of from about 20 to about 130 mg KOH/g when tested according to ASTM D2896. The amine contributes greater than about 30% of the TBN of the lubricant composition. Further, a method of lubricating an internal combustion engine with the lubricant composition comprises the steps of injecting a fuel and the lubricant composition into a cylinder to form a mixture, and combusting the mixture via compression-ignition.

An organophosphorus compound has a structure represented by the general formula (I):

##STR00001##

The functional groups are defined in the description. The organophosphorus compound has prominent bearing capacity and excellent antiwear and antifriction performances, and can be used as an extreme pressure antiwear additive and used in lubricating oil and lubricating grease.

Disclosed is a working fluid composition for a refrigerating machine, comprising a refrigerating machine oil comprising an ester of a polyhydric alcohol and a fatty acid, a carbodiimide compound, and a phosphorous compound, and at least one refrigerant selected from 1, 1, 1,2-tetrafluoroethane and 2,3,3,3-tetrafluoropropene, the fatty acid comprises at least one selected from fatty acids having 4 to 9 carbon atoms, and the carbodiimide compound and the phosphorus compound satisfy the conditions represented by the formula (1): $\begin{array}{cc}0.11\frac{\left(\frac{N_C}{M_C}.Math.W_C\right)}{\left(\frac{N_P}{M_P}.Math.W_P\right)}4.70& \left(1\right)\end{array}$
wherein, N.sub.c represents the number of carbodiimide groups per molecule of the carbodiimide compound, M.sub.c represents the molecular weight of the carbodiimide compound, W.sub.c represents the content of the carbodiimide compound, N.sub.p represents the number of phosphorus atoms per molecule of the phosphorus compound, M.sub.p represents the molecular weight of the phosphorus compound, and W.sub.p represents the content of the phosphorus compound.

A lubricant composition comprising lubricating oil and a compound containing phosphorus and an amine of formula I: ##STR00001##
wherein R.sup.1 is a hydrocarbon group and at least one of R.sup.1 is selected from: (C.sub.1-C.sub.20)alkyl, (C.sub.1-C.sub.20)alkenyl, (C.sub.5-C.sub.20)cycloalkyl; R is selected from: (C.sub.4-C.sub.20)alkyl, (C.sub.4-C.sub.20)alkenyl, (C.sub.5-C.sub.20)cycloalkyl; and wherein R.sup.2, R.sup.3 and R.sup.4 are independently selected from: H, (C.sub.6-C.sub.36)alkyl, (C.sub.6-C.sub.36)alkenyl, (C.sub.6-C.sub.36)cycloalkyl, wherein at least one of R.sup.2, R.sup.3 and R.sup.4 is not H; X is O or S; Y.sup.1 and Y.sup.2 are selected from S and O; m is 1 or 2, n is 0 or 1, p is 1 or 2, provided that m+n+p=3 and q=0.8 to 1.2*p, wherein the compound provides at least 48 ppm of phosphorus and a molar ratio phosphorus to nitrogen (P/N) in the range of about 0.40 to about 1.50.

Disclosed is a working fluid composition for a refrigerating machine, comprising a refrigerating machine oil comprising an ester of a polyhydric alcohol and a fatty acid, a carbodiimide compound, and a phosphorous compound, and at least one refrigerant selected from 1, 1, 1,2-tetrafluoroethane and 2,3,3,3-tetrafluoropropene, the fatty acid comprises at least one selected from fatty acids having 4 to 9 carbon atoms, and the carbodiimide compound and the phosphorus compound satisfy the conditions represented by the formula (1):

[00001]$\begin{array}{cc}0.11\frac{\left(\frac{N_C}{M_C}.Math.W_C\right)}{\left(\frac{N_P}{M_P}.Math.W_P\right)}4.70& \left(1\right)\end{array}$

wherein, N.sub.c represents the number of carbodiimide groups per molecule of the carbodiimide compound, M.sub.c represents the molecular weight of the carbodiimide compound, W.sub.c represents the content of the carbodiimide compound, N.sub.p represents the number of phosphorus atoms per molecule of the phosphorus compound, M.sub.p represents the molecular weight of the phosphorus compound, and W.sub.p represents the content of the phosphorus compound.

A lubricating grease composition, including 20 to 96.5 wt %, relative to a total weight of the lubricating grease composition, of a base oil, the base oil containing a basic oil A in a proportion of at least 50 wt %, relative to a total weight of the base oil, wherein the basic oil A is an ester and/or a polyglycol containing unsubstituted ethylene units as a carbon group in a repeating unit. The lubricating grease composition further includes 0.5 to 80 wt %, relative to the total weight of the lubricating grease composition, of an ionic liquid, the anion of the ionic liquid being bis(fluorosulfonyl)imide and 3 to 35 wt %, relative to the total weight of the lubricating grease composition, of a thickener selected from urea, lithium simple soaps, metal complex soaps of elements of the first and second main group of the periodic table, lithium complex soaps, and mixtures thereof.