Lubricating oil compositions with engine wear protection

Abstract

A method for improving wear control, while maintaining or improving fuel efficiency, in an engine or other mechanical component lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition including a lubricating oil base stock as a major component, and a mixture of (i) at least one carboxylic acid or metal salt of a carboxylic acid (e.g., metal stearate or stearic acid), and (ii) at least one surfactant (e.g., nonionic surfactant), as a minor components. A method for improving solubility, compatibility and dispersancy of polar additives in a lubricating oil is also provided. A lubricating oil having a composition including a lubricating oil base stock as a major component, and a mixture of (i) at least one carboxylic acid or metal salt of a carboxylic acid, and (ii) at least one surfactant, as minor components. The lubricating oils are useful in internal combustion engines.

What is claimed is: 
     
         1 . A method for improving wear control, while maintaining or improving fuel efficiency, in an engine or other mechanical component lubricated with a lubricating oil by using as the lubricating oil a formulated oil, said formulated oil having a composition comprising a lubricating oil base stock as a major component; and a mixture of (i) at least one carboxylic acid or metal salt of a carboxylic acid, and (ii) at least one surfactant, as minor components; wherein the minor components contain no sulfur or phosphorus; wherein the metal comprises a transition metal or mixtures thereof, and the carboxylic acid is selected from the group consisting of an aliphatic carboxylic acid, a cycloaliphatic carboxylic acid, an aromatic carboxylic acid, and mixtures thereof; wherein the surfactant is selected from the group consisting of nonionic, anionic, cationic, and amphoteric surfactants, and mixtures thereof; and wherein wear control is improved and fuel efficiency is maintained or improved as compared to wear control and fuel efficiency achieved using a lubricating oil containing minor components other than the mixture of (i) the at least one carboxylic acid or metal salt of a carboxylic acid, and (ii) the at least one surfactant. 
     
     
         2 . The method of  claim 1  wherein wear control is improved and deposit control, oxidation stability and fuel efficiency are maintained or improved as compared to wear control, deposit control, oxidation stability and fuel efficiency achieved using a lubricating oil containing minor components other than the mixture of (i) the at least one carboxylic acid or metal salt of a carboxylic acid, and (ii) the at least one surfactant. 
     
     
         3 . The method of  claim 1  wherein said formulated oil further comprises at least one co-base stock. 
     
     
         4 . The method of  claim 1  wherein the lubricating oil base stock comprises a Group I, Group II, Group III, Group IV or Group V base oil. 
     
     
         5 . The method of  claim 1  wherein the metal is selected from the group consisting of a Group 2, 10, 11, 12 and 15 metal, and mixtures thereof; and wherein the carboxylic acid is an aliphatic, saturated, unbranched carboxylic acid having from 8 to 26 carbon atoms, and mixtures thereof. 
     
     
         6 . The method of  claim 1  wherein the metal is selected from the group consisting of zinc (Zn), magnesium (Mg), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), bismuth (Bi), and mixtures thereof. 
     
     
         7 . The method of  claim 1  wherein the carboxylic acid is selected from the group consisting of caprylic acid (C8), pelargonic acid (C9), capric acid (C10), undecylic acid (C11), lauric acid (C12), tridecylic acid (C13), myristic acid (C14), pentadecylic acid (C15), palmitic acid (C16), margaric acid (C17), isostearic acid (C18), stearic acid (C18), nonadecylic acid (C19), arachidic acid (C20), heneicosylic acid (C21), behenic acid (C22), tricosylic acid (C23), lignoceric acid (C24), pentacosylic acid (C25), cerotic acid (C26), and mixtures thereof. 
     
     
         8 . The method of  claim 1  wherein the at least one carboxylic acid comprises stearic acid (C18), isostearic acid (C18), or mixtures thereof. 
     
     
         9 . The method of  claim 1  wherein the at least one metal salt of a carboxylic acid comprises zinc stearate, magnesium stearate, silver stearate, palladium stearate, zinc palmitate, silver palmitate, palladium palmitate, bismuth stearate, bismuth palmitate, or mixtures thereof. 
     
     
         10 . The method of  claim 1  wherein the at least one surfactant comprises a nonionic surfactant selected from the group consisting of alcohols, alkyloxylated alcohols, ethoxylated or propoxylated alcohols; ethylene oxide/propylene oxide block polymers, alkylpolyglucosides, ethoxylated oils and fats, alkanolamides, ethoxylated alkanolamides, ethoxylated fatty acids, glycol esters, glycerol esters, sorbitan esters, alkyl carbohydrate esters, trimesters of phosphoric acids, amine oxides, and mixtures thereof. 
     
     
         11 . The method of  claim 1  wherein the at least one surfactant is selected from the group consisting of sorbitan oleate, polyoxyethylene (5) nonylphenylether, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) average M n  1,100, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) average M n  2,000, octylphenol ethoxylate moles EO 1.5, octylphenol ethoxylate moles EO 9.5, and mixtures thereof. 
     
     
         12 . The method of  claim 1  wherein the weight ratio of the at least one carboxylic acid or metal salt of a carboxylic acid to the at least one surfactant is from 0.1:1 to 1000:1. 
     
     
         13 . The method of  claim 1  wherein the at least one carboxylic acid or metal salt of a carboxylic acid is present in an amount of from 0.001 weight percent to 5 weight percent, based on the total weight of the formulated oil. 
     
     
         14 . The method of  claim 1  wherein the at least one surfactant is present in an amount of from 0.001 weight percent to 20 weight percent, based on the total weight of the formulated oil. 
     
     
         15 . The method of  claim 1  wherein the lubricating oil base stock is present in an amount of from 6 weight percent to 95 weight percent, based on the total weight of the formulated oil. 
     
     
         16 . The method of  claim 1  wherein the formulated oil further comprises one or more of an antiwear additive, other viscosity modifiers, antioxidant, detergent, other dispersant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive. 
     
     
         17 . A method of improving solubility, compatibility and/or dispersancy of polar lubricating oil additives in a nonpolar lubricating oil base stock, said method comprising:
 providing a lubricating oil comprising a nonpolar lubricating oil base stock as a major component and one or more polar lubricating oil additives as a minor component; wherein said one or more polar lubricating oil additives comprise at least one carboxylic acid or metal salt of a carboxylic acid, and   blending at least one surfactant in the lubricating oil.   
     
     
         18 . The method of  claim 17  further comprising blending at least one co-base stock in the lubricating oil. 
     
     
         19 . A lubricating oil having a composition comprising a lubricating oil base stock as a major component; and a mixture of (i) at least one carboxylic acid or metal salt of a carboxylic acid, and (ii) at least one surfactant, as minor components; wherein the minor components contain no sulfur or phosphorus; wherein the metal comprises a transition metal or mixtures thereof, and the carboxylic acid is selected from the group consisting of an aliphatic carboxylic acid, a cycloaliphatic carboxylic acid, an aromatic carboxylic acid, and mixtures thereof; wherein the surfactant is selected from the group consisting of nonionic, anionic, cationic, and amphoteric surfactants, and mixtures thereof; and wherein wear control is improved and fuel efficiency is maintained or improved as compared to wear control and fuel efficiency achieved using a lubricating oil containing minor components other than the mixture of (i) the at least one carboxylic acid or metal salt of a carboxylic acid, and (ii) the at least one surfactant. 
     
     
         20 . The lubricating oil of  claim 19  wherein wear control is improved and deposit control, oxidation stability and fuel efficiency are maintained or improved as compared to wear control, deposit control, oxidation stability and fuel efficiency achieved using a lubricating oil containing minor components other than the mixture of (i) the at least one carboxylic acid or metal salt of a carboxylic acid, and (ii) the at least one surfactant. 
     
     
         21 . The lubricating oil of  claim 19  further comprising at least one co-base stock. 
     
     
         22 . The lubricating oil of  claim 19  wherein the lubricating oil base stock comprises a Group I, Group II, Group III, Group IV or Group V base oil. 
     
     
         23 . The lubricating oil of  claim 19  wherein the metal is selected from the group consisting of a Group 2, 10, 11, 12 and 15 metal, and mixtures thereof; and wherein the carboxylic acid is an aliphatic, saturated, unbranched carboxylic acid having from 8 to 26 carbon atoms, and mixtures thereof. 
     
     
         24 . The lubricating oil of  claim 19  herein the metal is selected from the group consisting of zinc (Zn), magnesium (Mg), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), bismuth (Bi), and mixtures thereof. 
     
     
         25 . The lubricating oil of  claim 19  wherein the carboxylic acid is selected from the group consisting of caprylic acid (C8), pelargonic acid (C9), capric acid (C10), undecylic acid (C11), lauric acid (C12), tridecylic acid (C13), myristic acid (C14), pentadecylic acid (C15), palmitic acid (C16), margaric acid (C17), isostearic acid (C18), stearic acid (C18), nonadecylic acid (C19), arachidic acid (C20), heneicosylic acid (C21), behenic acid (C22), tricosylic acid (C23), lignoceric acid (C24), pentacosylic acid (C25), cerotic acid (C26), and mixtures thereof. 
     
     
         26 . The lubricating oil of  claim 19  wherein the at least one carboxylic acid comprises stearic acid (C18), isostearic acid (C18), or mixtures thereof. 
     
     
         27 . The lubricating oil of  claim 19  wherein the at least one metal salt of a carboxylic acid comprises zinc stearate, magnesium stearate, silver stearate, palladium stearate, zinc palmitate, silver palmitate, palladium palmitate, bismuth stearate, bismuth palmitate, or mixtures thereof. 
     
     
         28 . The lubricating oil of  claim 19  wherein the at least one surfactant comprises a nonionic surfactant selected from the group consisting of alcohols, alkyloxylated alcohols, ethoxylated or propoxylated alcohols; ethylene oxide/propylene oxide block polymers, alkylpolyglucosides, ethoxylated oils and fats, alkanolamides, ethoxylated alkanolamides, ethoxylated fatty acids, glycol esters, glycerol esters, sorbitan esters, alkyl carbohydrate esters, trimesters of phosphoric acids, amine oxides, and mixtures thereof. 
     
     
         29 . The lubricating oil of  claim 19  wherein the at least one surfactant is selected from the group consisting of sorbitan oleate, polyoxyethylene (5) nonylphenylether, poly(ethylene glycol)-block-polypropylene glycol)-block-poly(ethylene glycol) average M n  1,100, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) average M n  2,000, octylphenol ethoxylate moles EO 1.5, octylphenol ethoxylate moles EO 9.5, and mixtures thereof. 
     
     
         30 . The lubricating oil of  claim 19  wherein the weight ratio of the at least one carboxylic acid or metal salt of a carboxylic acid to the at least one surfactant is from 0.1:1 to 1000:1. 
     
     
         31 . The lubricating oil of  claim 19  wherein the at least one carboxylic acid or metal salt of a carboxylic acid is present in an amount of from 0.001 weight percent to 5 weight percent, based on the total weight of the formulated oil. 
     
     
         32 . The lubricating oil of  claim 19  wherein the at least one surfactant is present in an amount of from 0.001 weight percent to 20 weight percent, based on the total weight of the formulated oil. 
     
     
         33 . The lubricating oil of  claim 19  wherein the lubricating oil base stock is present in an amount of from 6 weight percent to 95 weight percent, based on the total weight of the formulated oil. 
     
     
         34 . The lubricating oil of  claim 19  wherein the formulated oil further comprises one or more of an antiwear additive, other viscosity modifiers, antioxidant, detergent, other dispersant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive. 
     
     
         35 . The lubricating oil of  claim 19  which is a passenger vehicle engine oil (PVEO). 
     
     
         36 . A method for reducing sulfur and phosphorus and their harmful side effects of exhaust catalyst poisoning and increased corrosivity in an engine or other mechanical component lubricated with a lubricating oil by including a mixture of (i) at least one carboxylic acid or metal salt of a carboxylic acid, and (ii) at least one surfactant, in the lubricating oil; wherein the mixture contains no sulfur or phosphorus. 
     
     
         37 . A low sulfur, low phosphorus lubricating oil having a composition comprising a lubricating oil base stock as a major component, and a mixture of (i) at least one carboxylic acid or metal salt of a carboxylic acid, and (ii) at least one surfactant, as minor components. 
     
     
         38 . The method of  claim 1  wherein the formulated oil further comprises an antiwear additive, wherein the antiwear additive comprises zinc dialkyl dithio phosphate (ZDDP), and wherein the ZDDP is present in an amount less than 0.50 weight percent. 
     
     
         39 . The method of  claim 1  wherein wear control is improved and deposit control, oxidation stability, fuel efficiency, antioxidancy and detergency are maintained or improved as compared to wear control, deposit control, oxidation stability, fuel efficiency, antioxidancy and detergency achieved using a lubricating oil containing a minor component other than the mixture of (i) the at least one carboxylic acid or metal salt of a carboxylic acid, and (ii) the at least one surfactant.