GB2094339A

GB2094339A - Automotive transmission oils containing synthetic olefin oligomer base oils

Info

Publication number: GB2094339A
Application number: GB8204206A
Authority: GB
Original assignee: Lubrizol Corp
Current assignee: Lubrizol Corp
Priority date: 1981-02-20
Filing date: 1982-02-12
Publication date: 1982-09-15
Also published as: FR2500472A1; IT1147632B; GB2094339B; IT8247830A0; FR2500472B1; DE3206041A1

Abstract

Lubricating oils to be used in manual and automatic automotive transmissions comprise a carboxylate ester-free synthetic base oil comprising a liquid hydrocarbon- based olefin oligomer and a minor amount of phosphorus- and sulfur- containing extreme pressure agent(s). The oils have certain viscosity limits and phosphorus, and sulfur contents which make them useful as transmission oils.

Description

SPECIFICATION Synthetic olefin oligomer base oil composition and its use in manual and automatic transmissions Field of the invention This invention relates to transmission oils to be used in manual and automatic automotive transmissions. More particularly, it relates to manual and automatic transmission oils based on oligomers prepared from hydrocarbon-based olefins and extreme pressure agents. These extreme pressure agents contain the elements phosphorus and sulfur.

Discussion of prior art The lubrication of manual transmissions to be used in vehicles such as automobiles and trucks has, for years, been known to involve particular problems requiring specific solutions. For example, it is necessary to adequately lubricate the transmission at low temperature to prevent the phenomenon known as cold clashing. At the same time, it is desirable that the same oil be used to prevent problems developing in hot transmissions such as hot rattling and excessive rollover noise. Improperly functioning manual transmissions which often result from poor lubrication can both waste fuel and present dangerous operating conditions which sometimes result in serious accidents.

In the lubrication of automatic transmissions, proper fluid viscosity at both low and high temperatures is essential to successful operation. Good low temperature fluidity eases cold weather starting and insures that the hydraulic control system will properly "shift gears." High viscosity at elevated temperatures insures pumpability and the satisfactory functioning of converters, valves, clutches, gears and bearings.

These conflicting fluidity requirements call for a product that shows the following properties: a) High temperature viscosity retention b) Low temperature fluidity c) Shear stability.

Therefore, the search for useful oils to use in manual and automatic transmissions under all conditions of operation is of continuing interest.

The use of synthetic oils derived from oligomerization of olefins, particularly hydrocarbon olefins, is known; see, for example, the compilation "Synthetic Oils and Greases for Lubricants-Recent Developments" by M. William Ranney, published by the Noyes Data Corporation, Park Ridge, New Jersey, U.S.A., 1 976, particularly pages 292304. In general, these oils have been used as crankcase lubricants. See, for example, U.S. Patent 4,1 75,047 to Schick et al. Various patents and other prior art references have described useful techniques for producing such oils and compounding them; see, for example, U.S. Patent 3,149,1 78 to Hamilton et al.; 3,682,823 to Smith et al.; 3,780,128 to Schubkin; 4,032,591 to Cupples et al.; 4,167,534 to Petrillo et al.; and 4,175,046 to Coant et al.

All these patents and the Ranney compilation are hereby incorporated by reference herein for their disclosures relating. to oligomerized olefins, their manufacture and uses.

Summary of the invention This invention provides an oil composition comprising: (A) A carboxylate ester-free base oil comprising a major amount of a synthetic, liquid, hydrocarbon-based olefin oligomer; and (B) A minor amount of extreme pressure agent containing phosphorus and sulfur, said oil composition having a viscosity of less than about 100,000 cPs at 400 C. (according to ASTM Method D-2983), a phosphorus content of less than about 0.10 weight percent, and a sulfur content of less than about 1.5 weight percent.

Methods of operating an automotive manual transmission which comprise lubricating said transmission with the aforedescribed oil composition as well as automotive manual transmissions containing the oil composition are also within the scope of the invention.

This invention also provides a method of operating an automatic automotive transmission which comprises lubricating the transmission with an automatic transmission fluid composition comprising: (A-1) A base oil comprising a major amount of a synthetic, liquid, hydrocarbon-based olefin oligomer, and (B) A minor amount of extreme pressure agent containing phosphorus and sulfur, said automatic transmission fluid composition having a viscosity of less than about 50,000 cPs at -400C. (according to ASTM Method D-2983), a phosphorus content of less than about 0.10 weight percent and a sulfur content of less than about 1.5 weight percent.

The compositions of this invention solve the low temperature problems of manual and automatic transmissions described hereinabove, while maintaining the necessary high temperature protection.

The compositions of this invention provide excellent low temperature fluidity which, when used in automatic transmissions, results in improved fuel economy, startability, and operation at low temperatures. The compositions of this invention also provide improved oxidation inhibition properties.

Furthermore, the compositions of this invention have unexpectedly high shear stability. Additionally, the compositions of this invention provide excellent viscosity index (VI) properties which eliminates or reduces the need for Vl improver additives. This is particularly helpful in automatic transmission fluids where Vl properties are important.

Detailed description of the invention (A) The synthetic olefin oligomer.

As indicated above, the oil compositions of this invention comprise at least one carboxylate esterfree base oil which, in turn, is comprised of a major amount of at least one synthetic, liquid, hydrocarbon-based olefin oligomer. These base oils are carboxylate ester-free. This means they contain less than five percent carboxylate ester, particularly those carboxylate esters known to be useful as synthetic ester lubricants. See, for example, the carboxylate esters described in the text "Synthetic Lubricants" by Gunderson and Hart, Reinhold Publishing Corporation (1962), pages 151241, and 388-399 and the aforecited U.S. Patent 4,175,047.

The description of oils used in the present invention as "base oils" reflects the fact that the oil compositions are based upon them: in other words, the oils are the predominant oils in the lubricating oil composition. These oil compositions contain more than 50 percent by weight, generally, more than about 70 percent, often as much as 85 or 95 percent synthetic olefin oligomer oil. These olefin oligomer oils can be admixed with various other types of oils either hydrocarbyl or not (as long as the other descriptive parameters are met). Specific examples include alkylated benzene oils, silicate oils, polyglycol-based oils, and the like. Many such useful synthetic oils are known to the art.The synthetic oligomer oils of this invention can also be combined with various natural oils such as those derived from mineral sources (petroleum, coal, shale, etc.) as well as the other sources such as vegetables and animals. Typically, however, the oil compositions of the present invention contain base oils consisting essentially of synthetic olefin oligomer oil.

The synthetic oligomer oils of the present invention are liquid at room temperature and exhibit fluid flow at this temperature. Furthermore, their viscosity properties are such that at 400 C. the viscosity of the oil compositions based upon them can be measured by ASTM Method D2983 and found to be less than about 100,000 cPs at this temperature. This can be accomplished by having an olefin oligomer oil of the proper viscosity in itself or by blending an olefin oligomer with one or more other oils as indicated above to provide the desired viscosity properties.

The oil compositions of the present invention have a viscosity of less than about 100,000 cPs at 400 C. as measured by ASTM Method D-2983. Often they have a viscosity less than about 12,000 cPs at -400C. Typically, the oils of this invention have viscosities of less than about 20 centistokes at 1000C. More usually, the oil composition's viscosity is less than about 12 centistokes at 1000C.

The olefin oligomer oils upon which the oil compositions of this invention are based are hydrocarbon-based in nature. The term "hydrocarbon-based", when used herein, denotes a compound, composition and so forth having predominantly hydrocarbon character within the context of the invention. Such materials include the following: 1. Hydrocarbon compounds, compositions, etc., that is, aliphatic, (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl or cycloalkenyl), aromatic, aliphatic and alicyclic-substituted aromatic, aromaticsubstituted aliphatic and alicyclic materials, and the like.

2. Substituted hydrocarbon compounds, compositions, etc., materials containing nonhydrocarbon substituents which, in the context of this invention, do not alter the predominantly hydrocarbon character of the material. Those skilled in the art will be aware of suitable substituents; examples are:

(R being hydrogen or a hydrocarbon radical).

3. Hetero compounds, compositions, etc.; that is, materials which, while predominantly hydrocarbon in character within the context of this invention, contain atoms other than carbon present in a chain or ring otherwise composed of carbon atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for example, oxygen, sulfur and nitrogen.

In general, no more than about three substituents or hetero atoms, and preferably no more than one, will be present for each 10 carbon atoms in the hydrocarbon-based compound, composition or material.

Terms such as "alkyl-based" and the like have meanings analogous to the above with respect to alkyl materials and the like.

Preferably, the olefin oligomer base oils in the oil compositions of this invention are purely hydrocarbyl. Usually this means that the olefins used to make them are also purely hydrocarbyl in character.

The oligomeric base oils of this invention are made by oligomerizing one or more olefins to make a product which can serve as the base oil itself or in admixture as described above. Generally, these olefins will be monoolefins although in certain cases varying amounts of di-olefins, particularly nonconjugated di-olefins, can be used as long as the products provide oils having the appropriate properties. Similarly, these olefins are usually aliphatic in nature and therefore do not contain aromatic groups although relatively small amounts of aromatic-containing olefins can be used, particularly in admixture. The olefins used to produce the oligomeric base oils of this invention can have the olefinic (double) bond located in any position within their structure. Often a mixture is used having a statistical distribution of double bonds located in all possible positions.Typically, however, alpha-olefins (1olefins) are used exclusively or at least predominantly. Usually these alpha-olefins and, indeed, the other internal olefins are normal; that is, they are straight-chain compounds having no branching.

Branch-chain olefins, particularly in admixture, can also be used. Usually the olefins used in producing the oligomers used as base oils for the oil compositions of this invention contain about 6-1 B carbon atoms, usually about 812 carbon atoms. A mixture having a mean carbon content of about 10 carbon atoms (calculated on weight basis) can be used. Usually this fraction is purely hydrocarbyl in nature. As noted above, it is hydrocarbon-based in any event.

Preparation of the olefin oligomers used as base oils in the compositions of the present invention can be carried out by many techniques known to those of skill in the art. Among these techniques is cationic polymerization of the aforedescribed olefin mixtures, particularly the normal alpha-olefin mixtures of about 6-1 8 carbon atoms. Such cationic oligomerizations are usually catalyzed by Lewis acids. A number of such processes have been described; see, for example, U.S. Patents 3,149,178 (to Hamilton et al.); 3,376,360) (to Feezel); 3,382,291 (to Brennan); 3,576,898 (to Blake et al.); and 3,763,244 (to Shubkin), which are hereby incorporated by reference for their descriptions of methods of preparing olefin oligomers.

The oligomers used in base oils of the present invention are either hydrogenated oligomers or unhydrogenated oligomers. Methods of hydrogenating such oligomers are known. See, for example, the aforementioned '178 patent, as well as U.S. Patents 3,682,823 (to Smith et al.): 3,780,128 (to Shubkin): 3,808,134 (to Romine); 4,032,591 (to Cupples et al.); 4,167,534 (to Petrillo et al.); 4,175,046 (to Coant); and 4,175,047 (to Schick). Each of these is incorporated by reference herein for their disclosures relating to synthetic oils and, particularly, their hydrogenation. A base oil composed of only hydrogenated or only unhydrogenated oligomers can be used in the oil compositions of this invention.Alternatively, base oils comprised of mixtures of both types of oligomers, that is, hydrogenated/unhydrogenated, either by themselves or in admixture with other materials as indicated above can be used. Typically, however, the mixture is either only hydrogenated oligomers or of only unhydrogenated oligomers.

As indicated above, the base oils of this invention include olefinic oligomers in mixture with other materials such as those described above. Often, however, the base oil contains no more than about 10 percent by weight of natural or non-olefin synthetic oil and, in many cases consists essentially of synthetic, liquid hydrocarbon-based olefin oligomer. Typically, such oligomers are purely hydrocarbyl and of normal alpha -olefins having about 6-1 8 carbon atoms, often of normal alpha-olefins having a mean (by weight) carbon content of about 1 0 carbon atoms.

(B) The extreme pressure agents.

Extreme pressure of "E.P." additives and agents are well known to those of skill in the art. They are also often referred to as load-carrying agents. These materials are chemicals which are added to lubricating oils to prevent metal-to-metal contact between relatively moving surfaces during lubrication. Such metal-to-metal contact can lead to wear and ultimately catastrophic destruction of metal parts. Descriptions of extreme pressure agents are available in the prior art. See, for example, "Lubricant Additives" by Smalheer, and Kennedy, Lezius-Hiles Co., Cleveland, Ohio (1967), pages 911, particularly, and U.S. Patent 4,1 62,985. Both of these references are hereby incorporated by reference herein for their disclosures relating to E.P. agents.

The extreme pressure agents used in the oil compositions of the present invention contain phosphorus and sulfur, usually in chemically combined form. This does not mean that a single agent (or even a single compound in a given agent) contains both phosphorus and sulfur though this may be the case. It is sufficient that at least a phosphorus-containing and a second sulfur-containing agent, or compound be present. It is sometimes the case that both elements are present in a single agent or compound. In other cases, one agent or compound may contain both and the other but one. In still other cases, each agent or compound of two may contain phosphorus or sulfur. In addition, supplemental agents containing neither phosphorus or sulfur can be present. It is only necessary that at least one E.P. agent or combination of E.P agents containing sulfur and phosphorus be present.

Extreme pressure agents are usually organic compounds in the sense that they contain at least one organic moiety within their structure. They may be metal salts of organo acids in which case there are both inorganic and organic portions to the molecule. In other instances, they may be wholly organic and not contain any inorganic or metallic portion. Among the more typical extreme pressure agents for use in the oil compositions of this invention are the xanthates, sulfurized fatty oils, sulfur chloridetreated fatty oils, phospho-sulfurized fatty oils, benzyl and chlorobenzyl di-sulfides, alkyl polysulfides, mixtures of mono-, di- and tri-alkylphosphites, mixtures of mono- and di-alkarylphosphates, zinc and lead dia Ikyldithiocarbamates and zinc di-organodithiophosphates.Supplemental extreme pressure agents containing neither phosphorus nor sulfur include chlorinated paraffin waxes, lead soaps such as lead naphthanate, and other materials known to the art. A number of E.P. agents have been described in the art, including those noted above and still other types; see, for example, the disclosure in "Lubricant Additives-Recent Developments" by M. W. Ranney, Noyes Data Corporation, New Jersey (1978), particularly pages 165-204 which is hereby incorporated by reference for its disclosures in this regard.

Extreme pressure agents used in the oil compositions of this invention are often formulated in additive concentrates or packages and as such may contain one or more inert solvent/diluents which in turn may constitute one or more oils. Such oils are not considered to be base oils in the sense of this invention and in view of their relatively low concentration in the overall oil compositions of this invention they are not included in the term "base oils" as used herein.

The extreme pressure agent or agents used in the oil compositions of this invention are employed in a concentration so as to yield an oil composition having less than about 0.10 weight percent phosphorus and less than about 1.5 weight percent sulfur. Typically, they contain less than 0.05 percent phosphorus and less than 1.0 percent sulfur, and since the phosphorus and sulfur content of the agent may in itself be a relatively low percentage of its overall weight, this means that the extreme pressure agent can be used in amounts ranging between, for example, about 0.25-10.0 percent phosphorus-containing agent and about 0.2520 percent sulfur-containing agent. Usually, however, the extreme pressure agent or agents will be used in an amount between, for example, about 0.510 percent of each agent.If the agent used contains both phosphorus and sulfur it is used in concentrations to produce oil compositions having phosphorus and sulfur contents set forth above.

Generally the oil compositions of this invention contain at least about 0.01 weight percent of each phosphorus and sulfur. Typically, they contain at least about 0.02 percent phosphorus and about 0.2 percent sulfur.

Other known supplemental additives can be included in the oil compositions of this invention. For example, it is often desirable to include an anti-foam agent such as a silicone fluid of high viscosity such as a dimethyl silicone polymer having a kinematic viscosity at 250C. of about 1000 cPs. A typical anti-foam agent is prepared by diluting about 10 parts by weight of dimethyl silicone polymer with kerosene to provide 100 parts per weight solution. From 0.005 to 0.5 percent by weight of this concentrate is then employed in the finished oil composition. Anti-oxidants may also be used in the oil compositions of this invention. Amines often serve this function, particularly aryl-substituted amines such as phenyi naphthyl amines, phenylene diamines, and the like.They are typically used in concentrations ranging from 0.1 to 2.5 weight percent. Viscosity index improvers may be used in the compositions of this invention. Often such materials are high molecular weight polymers of, for example, acrylic esters such as the material sold by Rohm and Haas Company of Philadelphia, Pennsylvania under the trade name "ACRYLOID". Generally, relatively low amounts of such synthetic high molecular weight viscosity improvers can be used such as about 0.01 to about 2.5 percent (by weight) high molecular weight viscosity index improver. Hydrocarbyl viscosity index improvers can be also used such as hydrocarbyl polymers; polyisobutene polymers are particularly well known in this regard as viscosity index improvers, particularly those having molecular weights ranging from 50,000 to 250,000 and higher.Typically these are used in the amount of about 2.5 to 25 weight percent, sometimes about 420 percent, of the overall oil composition.

Other additives known to the art can also be included in the oil compositions of this invention so long as their cumulative effect is not such to exceed the viscosity or elemental parameters set forth above.

Examples Example I A transmission oil for manual transmissions is blended from 100 parts per weight synthetic olefin oligomer prepared by cationic polymerization of a normal olefin fraction having a mean carbon atom count of 1 0, 8.25 parts of a commercially available extreme pressure agent comprising a mixture of aliphatic amine salts of sulfur/oxygen-containing alkyl phosphoric acids and 0.25 parts by weight Acryloid 1 50. Blending is carried out to provide a homogeneous dispersion.

Example 2 A synthetic oil suitable for use as a manual transmission fluid is blended using the formulation of Example 1 with the addition of 15 parts by weight of a poly(isobutene) V.l. improver.

Example 3 An oil for manual transmissions based on synthetic lubricants is prepared by blending a mixedbase oil and the E.P. agent and foam inhibitor described in Example 1 in the amounts set forth in Example 1. The mixed-base oil comprises 55 percent by weight of the synthetic oligomer described in Example 1 and 45 percent by weight of a synthetic olefin oligomer oil having a viscosity of 40 cSt at 1000C. available from Uniroyal, Inc., Uniroyal Chemical Division of Naugatuck, Conn., U.S.A., under the trade name PAO 40.

The oil of Example 1 is placed as a transmission oil in a 5-speed manual transmission installed in a 1980 Ford Mustang automobile equipped with a 2-3 liter engine. It is found to lubricate the transmission satisfactorily under both cold and hot operating conditions.

As previously stated, this invention also provides a method of operating an automatic automotive transmission which comprises lubricating the transmission with an automatic transmission fluid composition comprising: (A-1) A base oil comprising a major amount of a synthetic, liquid, hydrocarbon-based olefin oligomer, and (B) A minor amount of extreme pressure agent containing phosphorus and sulfur.

The description of oils used in the automatic transmission fluids of this invention as "base oils" (A-i) ) reflects the fact that the oil compositions are based upon them; in other words, the oils are the predominant oils in the lubricating oil composition. These oil compositions contain more than 50 percent by weight, generally more than about 70 percent, often as much as 85 or 95 percent synthetic olefin oligomer oil. These olefin oligomer oils can be admixed with various other types of oils either hydrocarbyl or not (as long as the other descriptive parameters are met). Specific examples include alkylated benzene oils, carboxylate ester oils, silicate oils, polyglycol-based oils, and the like. Many such useful synthetic oils are known to the art.The synthetic olefin oligomer oils of this invention can also be combined with various natural oils such as those derived from mineral sources (petroleum, coal, shale, etc.) as weil as other sources such as vegetables and animals. Typically, however, the automatic transmission fluid compositions of the present invention contain base oils consisting essentially of synthetic olefin oligomer oil.

The synthetic oligomer oils of the present invention are liquid at room temperature and exhibit fluid flow at this temperature. Furthermore, their viscosity properties are such that at 40C C. the viscosity of the automatic transmission fluid compositions based upon them as measured by ASTM Method D2983 are found to be less than about 50,000 cPs at this temperature. This can be accomplished by having an olefin oligomer oil of the proper viscosity in itself or by blending an olefin oligomer with one or more other oils as indicated above to provide the desired viscosity properties.

The automatic transmission fluid compositions of the present invention have a viscosity of less than about 50,000 cPs at 400 C. as measured by ASTM Method DZ983. Often they have a viscosity less than about 12,000 cPs at 400 C. Typically, the fluids of this invention have viscosities of less than about 20 centistokes at 1000C. More usually, the fluid composition's viscosity is less than about 12 centistokes at 1000C. Typically, the automatic transmission fluid composition's viscosity is less than about 8 centistokes at 1 OODC.

The synthetic olefin oligomer oils upon which the automatic transmission fluid compositions of this invention are based are hydrocarbon-based in nature. The term "hydrocarbon-based", when used herein, denotes a compound, composition and so forth having predominantly hydrocarbon character within the context of the invention. Such materials include the following: 1. Hydrocarbon compounds, compositions, etc., that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl or cycloalkenyl), aromatic, aliphatic- or alicyclic-substituted aromatic, aromaticsubstituted aliphatic and alicyclic materials, and the like.

(R being hydrogen or a hydrocarbon radical).

3. Hetero compounds, compositions, etc.; that is, material which, while predominantly hydrocarbon in character within the context of this invention, contain atoms other than carbon present in a chain or ring otherwise composed of carbon atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for example, oxygen and nitrogen.

Preferably, the synthetic olefin oligomer oils in the automatic transmission fluid compositions of this invention are purely hydrocarbyl. Usually this means that the olefins used to make them are also purely hydrocarbyl in character.

The synthetic oligomeric oils of this invention are made by oligomerizing one or more olefins to make a product which can serve as the base oil itself or in admixture as described above. Generally, these olefins will be mono-olefins although in certain cases varying amounts of di-olefins, particularly non-conjugated di-olefins. can be used as long as the products provide oils having the appropriate properties. Similarly, these olefins are usually aliphatic in nature and therefore do not contain aromatic groups although relatively small amounts of aromatic-containing olefins can be used, particularly in admixture. The olefins used to produce the oligomeric base oils of this invention can have the olefinic (double) bond located in any position within their structure. Often a mixture is used having a statistical distribution of double bonds located in all possible positions.Typically, however, alpha-olefins (1olefins) are used exclusively or at least predominantly. Usually, these alpha-olefins and indeed, the other internal olefins are normal; that is, they are straight-chain compounds having no branching.

Branch-chain olefins, particularly in admixture, can also be used. Usually, the olefins used in producing the oligomers used as base oils for the automatic transmission fluid compositions of this invention contain about 6-1 8 carbon atoms, usually about 8-1 2 carbon atoms. A mixture having a mean carbon content of about 10 carbon atoms (calculated on weight basis) can be used. Usually this fraction is purely hydrocarbyl in nature. As noted above, it is hydrocarbon-based in any event.

Preparation of the synthetic olefin oligomers used as base oils in the automatic transmission fluid compositions of the present invention can be carried out by many techniques known to those of skill in the art. Among these techniques is cationic polymerization of the aforedescribed olefin mixtures, particularly the normal alpha-olefin mixtures of about 6-1 8 carbon atoms. Such cationic oligomerizations are usually catalyzed by Lewis acids. A number of such processes have been described; see, for example, U.S. Patents 3,149,178 (to Hamilton et al.); 3,376,360 (to Feezel); 3,382,291 (to Brennan); 3,576,898 ito Blake et al.); and 3,763,244 (to Shubkin), which are hereby incorporated by reference for their descriptions of methods of preparing olefin oligomers.

The synthetic olefin oligomers used as base oils in the automatic transmission fluid compositions of the present invention are either hydrogenated oligomers or unhydrogenated oligomers. Methods for hydrogenating such oligomers are known. See, for example, the aforementioned t 178 patent, as well as U.S. Patents 3,682,823 (to Smith et al.); 3,780,128 (to Shubkin); 3,808,134 (to Romine); 4,032,591 (to Cupples et al.); 4,167,534 (to Petrillo et. al.); 4,175,046 (to Coant); and 4,175,047 (to Schick). Each of these is incorporated by reference herein for their disclosures relating to synthetic oils and, particularly, their hydrogenation. A base oil composed of only hydrogenated or only unhydrogenated oligomers can be used in the oil compositions of this invention.Alternatively, base oils comprised of mixtures of both types of oligomers, that is, hydrogenated/unhydrogenated, either by themselves or in admixture with other materials as indicated above can be used. Typically, however, the mixture is either only hydrogenated oligomers or of only unhydrogenated oligomers.

As indicated above, the base oils used in the automatic transmission fluid compositions of this invention include olefinic oligomers in mixture with other materials such as those described above.

Often, however, the base oil contains no more than about 10 percent by weight of natural or non-olefin derived synthetic oil and, in many cases consists essentially of synthetic, liquid hydrocarbon-based olefin oligomer. Typically, such oligomers are purely hydrocarbyl and derived from normal alpha-olefins having about 618 carbon atoms, often from normal alpha-olefins having a mean (by weight) carbon content of about 10 carbon atoms.

Extreme pressure or "E.P." additives and agents (B) are well known to those of skill in the art.

They are also often referred to as load-carrying agents. These materials are chemicals which are added to lubricating oils to prevent metal-to-metal contact between relatively moving surfaces during lubrication. Such metal-to-metal contact can lead to wear and ultimately catastrophic destruction of metal parts. Descriptions of extreme pressure agents are available in the prior art. See, for example, "Lubricant Additives" by Smalheer, and Kennedy, Lezius-Hiles Co., Cleveland, Ohio (1967), pages 911, particularly, and U.S. Patent 4,162,985. Both of these references are hereby incorporated by reference herein for their disclosures relating to E.P. agents.

The extreme pressure agents used in the automatic transmission fluid compositions of the present invention contain phosphorus and sulfur, usually in chemically combined form. This does not mean that a single agent (or even a single compound in a given agent) contains both phosphorus and sulfur though this may be the case. It is sufficient that at least a phosphorus-containing and a second sulfur-containing agent, or compound be present. It is sometimes the case that both elements are present in a single agent or compound. In other cases, one agent or compound may contain both and the other but one. In addition, supplemental agents containing neither phosphorus or sulfur can be present. It is only necessary that at least one E.P. agent or combination of E.P. agents containing sulfur and phosphorus be present.

Extreme pressure agents are usually organic compounds in the sense that they contain at least one organic moiety within their structure. They may be metal salts of organo acids in which case there are both inorganic and organic portions to the molecule. In other instances, they may be wholly organic and not contain any inorganic or metallic portion. Among the more typical extreme pressure agents for use in the oil compositions of this invention are organic sulfides and polysulfides, such as benzyldisulfide, bis-(chlorobenzyl) disulfide. dibutyltetrasulfide, sulfurized sperm oil, sulfurized methyl ester of oleic acid. sulfurized terpene. sulfurized Diels Alder adducts, hydroxy thioethers, and the like; phosphosulfurized hydrocarbons, such as the reaction product of phosphorus sulfide with turpentine or methyl oleate; phosphorus esters such as dihydrocarbon and trihydrocarbon phosphites, i.e., dibutyl phosphite, diheptyl phosphite, dicyclohexylphosphite, dipentyl phenyl phosphite, tridecyl phosphite, distearyl phosphite, and polypropylene substituted phenol phosphite; metal thiocarbamates, such as zinc dioctylthiocarbamates and barium heptylphenyl dithiocarbamate; and Group II metal salts of phosphorodithioic acids such as zinc dicyclohexylphosphorodithioate and the zinc salts of phosphorodithioic acid. Supplemental extreme pressure agents containing neither phosphorus nor sulfur include chlorinated paraffin waxes, lead soaps such as lead naphthanate, and other materials known to the art. A number of E.P. agents have been described in the art, including those noted above and still other types; see, for example, the disclosure in "Lubricant Additives-Recent Developments" by M. W. Ranney, Noyes Data Corporation, New Jersey (1978), particularly pages 165204, which is hereby incorporated by reference for its disclosures in this regard.

Extreme pressure agents used in the automatic transmission fluid compositions of this invention are often formulated in additive concentrates or packages and as such may contain one or more inert solvent/diluents which in turn may constitute one or more oils. Such oils are not considered to be base oils in the sense of this invention and in view of their relatively low concentrate in the overall oil compositions of this invention they are not included in the term "base oils" as used herein.

The extreme pressure agent or agents used in the automatic transmission fluid compositions of this invention are employed in a concentration so as to yield an oil composition having less than about 0.10 weight percent phosphorus and less than about 1.5 weight percent sulfur. Typically, they contain less than 0.05 percent phosphorus and less than 1.0 percent sulfur, and since the phosphorus and sulfur content of the agent may in itself be a relatively low percentage of its overall weight, this means that the extreme pressure agent can be used in amounts ranging between, for example, about 0.25 10.0 weight percent phosphorus-containing agent and about 0.25-20.0 weight percent sulfurcontaining agent.Usually, however, the extreme pressure agent or agents will be used in an amount between, for example, about 0.510 weight percent of each agent. If the agent used contains both phosphorus and sulfur it is used in concentrations to produce automatic transmission fluid compositions having phosphorus and sulfur contents set forth above. Generally, the automatic transmission fluid compositions of this invention contain at least about 0.01 weight percent of each phosphorus and sulfur. Typically, they contain at least about 0.02 percent phosphorus and about 0.2 percent sulfur.

In addition to the base oil (A-1) and the extreme pressure agent (B) the automatic transmission fluid compositions of this invention preferably contain one or more lubricating oil dispersants (C). These dispersants are characterized by their ability to suspend and/or disperse sludge, etc. in lubricating compositions and are oil-soluble or stably dispersible in lubricating compositions at the proportions and in the environment employed.

The dispersants, when employed, are used at a level of from about 0.01% to about 20% by weight or higher, depending on such factors as the nature of the dispersant and nature of the lubricating oil. Usually, such dispersants are employed at a level of from about 0.1% to about 15% by weight. These percentages refer to the percent by weight based on the total weight of the final lubricating oil composition.

The terminology "dispersant" as used in the present specification and claims refers to those materials selected from the group consisting of (C-1) ) high molecular weight acylated nitrogen-based dispersants; (C-2) high molecular weight ester-based dispersants; (C-3) high molecular weight Mannich-based dispersants; (C-4) high molecular weight hydrocarbyl amine-based dispersants; (C5) post-treated products of one or more of (C-1) through (C--4); (C-6) interpolymeric dispersants having repeating pendant groups of up to about 24 carbon atoms; and (C-7) mixtures of two or more of any of the dispersants included in (C-1) ) through (C-6).Preparation and use of these dispersants are generally known in the art.

(C--l) High molecular weight acylated nitrogen-based dispersants.

These dispersants can be generally characterized as materials having at least one high molecular weight oil-solubilizing group which is a hydrocarbon-based group ordinarily having at least about 30 aliphatic carbon atoms and further characterized as having at least one nitrogen atom directly attached to a polar group.

The dispersants of Class (C-1) are usually complex mixtures whose precise composition is not readily identifiable. Accordingly, such dispersants are frequently described in terms of a method of preparation. Examples of dispersants of Class (C-1) are described in many U.S. patents including: 3,172,892 3,341,542 3,630,904 3,215,707 3,444,170 3,632,511 3,219,666 3,448,048 3,787,374 3,272,746 3,454,607 3,804,763 3,316,177 3,541,012 3,836,470 The above U.S. patents are expressly herein incorporated by reference for their teaching of preparation and use of dispersants within Class (C-i).

A convenient route in the preparation of dispersants of Class (C-1) comprises the reaction of a "carboxylic acid acylating agent" with a nitrogen-containing compound such as an amine, either alone, or in further combination with an organic hydroxy compound. As used herein, "carboxylic acid acylating agent" describes an acid or derivatives thereof such as an anhydride, acid halide, ester, amide, imide or amidine or the like. These carboxylic acid acylating agents have been described previously in detail.

They include monocarboxylic acid acylating agents or polycarboxylic acid acylating agents.

Monocarboxylic and polycarboxylic acid acylating agents have been described, for example, in U.S. Patents 3,087,936; 3,163,603; 3,172,892; 3,189,544; 3,219,666; 3,272,746; 3,288,714; 3,306,907; 3,331,776; 3,340,281; 3,341,542; 3,346,354; 3,381,022 and 3,755,169. For the sake of brevity, these patents are incorporated herein by reference for their teaching of the preparation and use of mono- and polycarboxylic acid acylating agents. Preferred acylating agents usually contain at least about 50 aliphatic carbon atoms in the substituent atoms.

The preparation of typically useful monocarboxylic acid acylating agents is disclosed in U.S.

Patent 3,833,624 in columns 2-4, lines 51-73, 1-75, and 135, respectively. This disclosure is expressly herein incorporated by reference for its teaching of monocarboxylic acid acylating agents, their preparation and use. U.S. Patents 3,697,428 discloses polycarboxylic acid acylating agents at columns 2 4, lines 21-72, 1-75 and 148, respectively. This disclosure is also expressly herein incorporated by reference for its teaching of the preparation and use of polycarboxylic acid acylating agents. Typically, these mono- and polycarboxylic acid acylating agents are conveniently formed from halogenated olefin polymers which are reacted with o',-unsaturated acids, anhydrides, esters and the like.

Preferred carboxylic acid acylating agents are mono- and dicarboxylic acid acylating agents corresponding to compounds such as hydrocarbon-based substituted acrylic acids and hydrocarbonbased substituted succinic anhydrides or acids.

Useful nitrogen-containing compounds for the preparation of dispersants of Class (C-i) include mono- and poly-primary or secondary amines, characterized by a radical having the configuration

The two remaining valences of the nitrogen atom of the

radical preferably are satisfied by hydrogen, amino, substituted amino, or organic radical bonded to said nitrogen atom through a direct carbon-to-nitrogen linkage. These amines include ammonia, aliphatic monoamines and polyamines, hydrazines, aromatic amines, heterocyclic amines, carboxylic amines, aryiene amines, alkylene amines, N-hydroxyaikyl substituted amines and the like. Usually alkylene polyamine containing two or three carbon atoms in the alkylene moieties and from two to ten amino nitrogen atoms having one or two hydrogens per amino nitrogen will be used.The ethylene polyamines such as diethylene triamine, tetraethylene polyamine, and mixtures thereof including commercial mixtures containing piperazine, aminoethoxy piperazines, etc., are preferred.

Further examples of such amines appear in U.S. Patent 3,879,308 at columns 10 and 11, lines 1168 and 153. This disclosure of typically useful amines is expressly herein incorporated by reference. Other types of amines including specific examples are disclosed, of course, in the above patents relating to high molecular weight acylated nitrogen-based dispersants.

The reaction between the nitrogen-containing compounds (e.g., amine) and the carboxylic acid acylating agent results in the direct attachment of a nitrogen atom to a polar radical derived from the acylating group. The linkage formed between the nitrogen atom and the polar radical may be characterized as an amide, imide, amidine, salt or mixtures of these radicals. The exact relative proportions of these radicals in a particular product may not be precisely known since it depends to a large extent upon the acylating agent, nitrogen compound and the conditions under which the reaction is carried out. For example, a reaction involving an acid or an anhydride with amines at temperatures below about 500 C. will result predominantly in a salt linkage. However, reactions at relatively higher temperatures, e.g., above 800 C. and up to about 2500C. or higher results in predominantly an imide, amide, amidine linkage or mixtures thereof.

Generally, however, the dispersants of Class (C-i) may be characterized in that they contain at least one acyl, acyloxy or acylimidoyl group having at least about 50 carbon atoms which is bonded directly to a nitrogen. The structures of these groups, as defined by the International Union of Pure and Applied Chemistry, are as follows: (R representing a monovalent hydrocarbon-based group or similar group);

The high molecular weight acylated nitrogen-based dispersants of Class (C-i) can also contain other polar groups. For example, the carboxylic acid acylating agent can be reacted with a polyhydric alcohol and thereafter be reacted with an amine. Such a high molecular weight acylated nitrogenbased dispersant is described in U.S. Patent 3,836,470.Alternatively, for example, a polycarboxylic acid acylating agent can be reacted with, for example, an alkylene polyamine, and the resulting reaction product contacted with certain polyhydric alcohols. Such acylated nitrogen-based dispersants are described in U.S. Patent 3,632,511. These latter two U.S. patents are expressly incorporated herein by reference for their disclosure of the preparation and use of such dispersants.

For a better understanding of the high molecular weight acylated nitrogen-based dispersants, several specific examples of such dispersants are set forth in Table I.

Table 1 Ratio of Reaction Carboxylic acid Nitrogen containing equivalents, temperature, Example acylating agent (I) compound (e.g. amine) (II) I:II C A-1 Polyisobutenyl (mol. wt.* Polyethylene amine mixture 0.48 150 about 900) succinic an- containing 3-7 amino hxdride prepared from groups per molecule chlorinated polyisobutene A-2 Same as Example 1 Commercial pentaethylene 0.41 150 hexamine A-3 Like Example 1 except Commercial pentaethylene 0.61 150 polyisobutene mol. wt.* hexamine is about 1050 A-4 Like Example 1, Except Diethylene triamine 1.0 150 polyisobutene mol. wt.* is about 850 A-5 Same as Example 4 Ethylene diamine 1.0 150 A-6 Same as Example 4 DI-(1,2-propylene)triamine 1.0 180-190 A-7 Same as Example 4 N-(2-hydroxyethyl)- 1.08 150-155 trimethylene diamine A-8 Same as Example 1 20 parts (by weigth) amine 0.91 150 mixture of Example 1,80 parts triethylene tetramine A-9 Same as Example 1 Same as Example 1 1.33 150 A-10 Like Example 1, except Pentaerythritol, followed by 0.44 150-210 polyisobutene mol. wt.* polyethylene amine of Example 1 is about 1100 (ratios of equivalents of alcohol to amine 7.7:1) *Number average molecular weigth as determined by Vapor Phase Osmometry (C-2) High molecular weight ester-based dispersants.

The high molecular weight ester-based dispersants can be generally characterized as containing at least one hydrocarbon-based group having at least about 30 aliphatic carbon atoms and further characterized as having at least one ester group. For convenience of description, these high molecular weight ester-based dispersants of Class (C-2) are substantially free of groups formed by the reaction of an amino nitrogen with an acylating agent inasmuch as such dispersants are included in Class (C1) above.

The dispersants of Class (C-2) are well known in the art. Exemplary of such dispersants are those disclosed in the following U.S. patents: 3,381,022 3,697,428 3,522,1 79 3,833,624 3,542,678 3,838,052 3,542,680 3,879,308 3,576,743 These patents are herein expressly incorporated by reference for their teaching of the use and preparation of high molecular weight ester-based dispersants.

The dispersants of Class (C-2) are ordinarly complex mixtures of ester-containing materials whose precise composition and/or structure is not often readily identifiable. Accordingly, such dispersants of Class (C-2) are frequently described in terms of their method of preparation.

The dispersants of Class (C-2) are generally prepared by the reaction of a carboxylic acid acylating agent as described above in Class (C-i) with an organic mono- or polyhydroxy compound.

Moreover, included with the dispersants of Class (C-2) are those materials prepared by the reaction of a carboxylic acid acylating agent with a mono- or polyhydroxy compound which is thereafter again reacted with a carboxylic acid acylating agent. Typically useful organic mono- and polyhydroxy compounds are quite diverse in structure.

The hydroxy compounds may be aliphatic monohydric and polyhydric alcohols and aromatic hydroxy compounds such as phenols and naphthols. The monohydric alcohols include methanol, ethanol, isooctanol, dodecanol, cyclohexanol, eicosanol, neopentyl alcohol, isobutyl alcohol, and the like. The polyhydric alcohols will normally contain from 2 to about 10 hydroxy radicals. These polyhydric alcohols are illustrated by, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and other alkylene glycols in which the alkylene radical contains from about 2 to about 8 carbon atoms. Other useful polyhydric alcohols include glycerol, monooleate of glycerol, monostearate of glycerol, monomethyl ether of glycerol, pentaerythritol, 9,10dihydroxy stearic acid, sorbitol, mannitol, 1 ,3-cyclohexanediol, and the like.Carbohydrates with free hydroxy groups such as sugars, starches, and celluloses, are useful in the preparation of a high molecular weight ester-based dispersants of Class (C-2). These carbohydrates may be exemplified by glucose, fructose, sucrose, mannose, and galactose.

Typically useful mono- and polyhydroxy aromatic compounds include those wherein the aromatic nucleus of the aromatic compound is a benzene ring or an aromatic condensed hydrocarbon ring such as naphthalene. Monohydroxy and polyhydroxy phenols and naphthols are especially useful hydroxy aromatic compounds. Exemplary of such mono- and polyhydroxy aromatic compounds are those disclosed in U.S. Patent 3,542,680 which is expressly herein incorporated by reference for its disclosure of high-molecular weight ester-based dispersants utilizing mono- and polyhydroxy aromatic compounds.

Preferred organic hydroxy compounds include those which are polyhydric aliphatic alcohols containing up to 10 carbon atoms. Within this class are an especially preferred class of polyhydric alcohols including polyhydric alkanols containing 3 to 10, and more preferably 3 to 6 carbon atoms, and having at least 3 hydroxyl groups. Such alcohols are exemplified by glycerol; 2-hydroxymethyl-2 methyl-1,3-propanediol (i.e., TME); 2-hydroxymethyl-2-ethyl-1 ,3-propanediol (i.e., TMP); 1,2,4butanetriol, 1 2,6-hexanetriol; 1 ,2,3-pentanetriol; and the like. For a better understanding of these high molecular weight ester-based dispersants, specific examples of such dispersants are set forth in Table II.

Table II Weight ratio of Reaction Carboxylic acid Organic hydroxy acylating agent to temperature, Example acylating agent (I) compound organic hydroxy compound C.

A-11 Polyisobutylene (mol. wt.* sorbitol 81:5 115-205 about 1000) acrylic acid prepared from chlorinated polyisobutylene and acrylic acid A-12 Polyisobutylene (mol. wt.* 2-hydroxymethyl-2- 397:96 170-220 about 1100-1130) succinic ethyl-1,3-propanediol (TMP) anhydride prepared from and; pantaerythritol at chlorinated polyisobutylene 1:1 ratio by weigth and maleic anhydride A-13 Polyisobutylene (mol. wt.* phenol 514:141 153 about 1025) succinic anhy dride prepared from chlori nated polyisobutylene and maleic anhydride A-14 Polyisobutylene (mol. wt.* buthyl 9,10-hydroxystyrearate 397:96 170-220 about 1000) succinic anhydride prepared from chlorinated polyisobutylene and maleic anhydride *Number Average Molecular Weigth as determined by Vapor Phase Osmometry (C-3) High molecular weight Mannich-based dispersants.

The dispersants of Class (C-3) can be characterized as reaction products of alkyl phenols in which the alkyl group contains at least about 30 carbon atoms with lower aliphatic aldehydes (especially formaldehyde) and amines (especially polyalkylene polyamines). These dispersants are well known in the art and are described in the following U.S. patents: 3,169,516 3,725,277 3,413,347 3,736,357 3,448,047 3,772,359 3,591,598 3,798,165 3,649,229 3,872,019 These patents are herein expressly incorporated by reference for their teaching of the preparation and use of Mannich-based dispersants.

High molecular weight Mannich-based dispersants are often complex mixtures whose precise composition is not readily identifiable. Accordingly, these materials are frequently described in terms of their method of preparation. Thus, for example, a hydroxy aromatic compound is reacted with a carbonyl compound and a compound containing at least one primary or secondary amino group to form the dispersants within Class (C-3).

Representative high molecular weight alkyl-substituted phenols include polypropylenesubstituted phenol, polybutylene-substituted phenol, polyamylene-substituted phenol and similarly substituted phenols. In place of the phenol, high molecular weight alkyl-substituted compounds of resorcinols, hydroquinones, catechols, cresols, xylenols and the like, can be employed.

Typical aldehydes are the aliphatic aldehydes, such as formaldehyde, acetaldehyde, and ,B- hydroxybutraldehyde; aromatic aldehyde, such as be nzalde hyde, heterocyclic aldehydes, such as furfural; etc. Preferred aldehydes are, however, aliphatic aldehydes with formaldehyde being particularly preferred.

Useful amines include those which contain an amino group characterized by the presence of at least one active hydrogen atom. Typical amines are the alkylene polyamines such as ethylene diamine, propylene diamine, polyalkylene polyamines such as diethylene triamine, triethylene tetramines; hydroxy amines such as hydroxy-substituted alkylene amines and polyalkylene polyamines, and the aromatic amines such as o-, m-, and p-phenylamines. Heterocyclic amirles which are suitable are those characterized by attachment of a hydrogen atom to a nitrogen atom in heterocyclic group.

Representative of these amines are morpholine, thiomorpholine, imadazoline, and piperidine.

Typical specific examples of the dispersants of Class (C-3) are found in the above-cited patents disclosing Mannich-base dispersants.

(C 4) Hydrocarbyl amine-based dispersants.

The dispersants of Class (C4) can be generally characterized as high molecular weight materials having at least one amino moiety attached to a hydrocarbyl group of at least about 30 carbon atoms. Mineral acid salts of these amines are also included in Class (C ti) as, for example, those dispersants in U.S. 3,573,010. These dispersants are well known in the art. The following U.S. patents are exemplary of the preparation and use of such dispersants and are herein incorporated by reference: 3,275,554 3,671,511 3,373,112 3,755,433 3,438,757 3,822,209 3,454,555 3,869,514 3,565,804 3,873,460 3,573,010 The dispersants of Class (C-4) can be readily prepared by combining an aliphatic or alicyclic halide with the desired amine in appropriate molar proportions.The halide can be derived from a hydrocarbon by halogenation and the hydrocarbon is usually derived from the polymerization of olefins containing from about 2 to 6 carbon atoms. Typical olefins which find use are propylene, isobutylene, 1-pentene, and 4-methyl-1-pentene. Usually preferred olefins are propylene and isobutylene.

Typical hydrocarbyl amine dispersants conform for the most part to the formula

wherein W is alkylene from 2 to 6 carbon atoms; a is an integer from 0 to 10; b is an integer of O or 1; a+2b is an integer from 1 to 10; c is an integer in a range from 1 to 5 and averages in the range of 1 - 4 over the entire composition and is less than the number of amine nitrogens in the molecule; and R5 is a hydrocarbyl group of at least about 30, preferably 60 to 200 aliphatic carbon atoms. Thus, these high molecular weight hydrocarbyl amines include mono- and polyamines substituted with at least one high molecular weight hydrocarbyl group. The amines of Class (C4) can be hydroxy-substituted amines as well.

(C--5) Post-treated products of Classes (C-i), C-2), C-3) and (C 4).

The dispersants of Classes (C-i )-(C-4) can be post-treated with such reagents as urea, thiourea, carbon disulfide, aldehyde, ketones, anhydrides, nitriles, epoxides, boron compounds, metal salts, phosphorus compounds and the like to form oil-soluble or stably dispersible dispersants.

Exemplary materials of this kind are described in the following U.S. patents: 3,036,003 3,281,428 3,502,677 3,639,242 3,087,936 3,282,955 3,513,093 3,649,229 3,200,107 3,367,943 3,533,945 3,697,574 3,216,936 3,403,102 3,539,633 3,702,757 3,254,025 3,455,831 3,579,450 3,703,536 3,256,185 3,455,832 3,591,598 3,704,308 3,278,550 3,493,520 3,600,372 3,912,641 These patents are incorporated herein by reference for their teaching of the preparation and use of post-treated dispersants of Classes (C1)(C 4).

(C-6) Interpolymeric dispersants having repeating pendant groups of up to about 24 carbon atoms.

These dispersants of Class (C-6) can be characterized as materials which normally can serve to improve the viscosity index of lubricating compositions and also function as dispersants. The repeating pendant groups are normally oil-solubilizing groups (i.e., function to enhance the solubility of the interpolymeric dispersant in oil).

The interpolymeric dispersants are generally used in combination with any of the dispersants of Classes (C-i )-(C-5) above, but may be used alone in the lubricating compositions without other dispersants. The interpolymeric dispersants are distinguished from the dispersants of Classes (C-i)- (C--5) by the repeating character of the pendant groups. The interpolymeric dispersants also normally do not contain aliphatic carbon chains of over about 24 carbon atoms. Many examples of these materials are known to those in the art. Some of these examples are in U.S.Patents: 3,329,658 3,687,849 3,449,250 3,702,300 3,519,565 3,933,761 3,666,730 which are hereby incorporated by reference for their teaching of the preparation and use of interpolymeric dispersants having repeating pendant groups of up to about 25 carbon atoms. A preferred type interpolymeric dispersant is that type of dispersant disclosed in U.S. Patent 3,702,300 (above) which is a nitrogen-containing mixed alkyl ester of a styrene-maleic anhydride copolymer having mixed-ester radicals of from 1 to 24 carbon atoms.

(C-7) Mixtures of dispersants of Classes (C-i )-(C-6).

Mixtures of one or more dispersants from those within any of the Classes (C-i) ) through (C-S) can also be employed, especially and preferably combinations of boron post-treated dispersants with other dispersants.

In a preferred aspect of this invention the automatic transmission fluid compositions comprise (A-i) and (B) in combination with a boron-containing dispersant (C4). Boron-containing dispersants have been disclosed in the prior art as being useful in lubricating compositions.Typical of these boron-containing dispersants are those disclosed in the following U.S. patents: U.S. Patents-Dispersant type 3,000,916 borated, acylated nitrogen-based 3,087,936 borated, acylated nitrogen-based 3,254,025 borated, acylated nitrogen-based 3,281,428 borated, acylated nitrogen-based 3,282.955 borated, acylated nitrogen-based 3,306,908 borated, acylated nitrogen-based 3,344,069 borated, acylated nitrogen-based 3,449,362 borated, acylated nitrogen-based 3,666,662 borated, acylated nitrogen-based 3,533,945 borated, ester-based 3,442,808 borated, Mannich-based 3,539,633 borated, Mannich-based 3,697,574 borated, Mannich-based 3,703,536 borated, Mannich-based 3,704,308 borated, Mannich-based 3,751,365 borated, Mannich-based 3,658,836 borated, hydrocarbyl amine-based These patents are hereby incorporated by reference for their disclosure regarding the preparation and use of boron post-treated dispersants.

Particularly preferred of the boron-containing dispersants are boron post-treated acylated nitrogen-based dispersants described in U.S. Patents 3,087,936 and 3,254,025 which are herein incorporated by reference for their relevant disclosure of the preparation and use of such dispersants.

These dispersants are nitrogen and boron-containing compositions obtained by treating an acylated nitrogen-based dispersant (see the description of Class (C-i) above) characterized by the presence within its structure of (a) a hydrocarbon-based substituted succinic radical selected from the class consisting of succinoyl, succinimidoyl, succinoyloxy radicals wherein the hydrocarbon-based substituent contains at least about 50 aliphatic carbon atoms and (b) a nitrogen-containing group characterized by a nitrogen atom attached directly to the succinic radical, with a boron compound selected from the group consisting of boron oxide, boron halide, boron acids, and esters of boron acids in an amount to provide from about 0.1 atomic proportion of boron for each mole of the acylated nitrogen-based dispersant to about 10 atomic proportions of boron for each atomic proportion of nitrogen of the acylated nitrogen-based dispersant.

Especially preferred boron-containing dispersants are prepared by forming an acylated nitrogen based intermediate by the reaction at a temperature within the range from about 800 C. to about 2500C., of a substantially aliphatic olefin polymer-substituted succinic acid acylating agent having at least about 50 aliphatic carbon atoms in the polymer substituent with at least about one-half of an amine equivalent for each equivalent of the acylating compound used, selected from the group consisting of alkylene amines and hydroxy-substituted alkylene amines, and reacting, at a temperature between about 500 C. and about 2500 C., the high molecular weight acylated nitrogen intermediate with a boron compound selected from the group consisting of boron oxide, boron halide, boron acids, and esters of boron acids in an amount to provide a boron content as specified hereinabove.

Particularly preferred among this subclass of boron-containing dispersants are those where the hydrocarbon substituents of (a) is a polyisobutene having a number average molecular weight of about 700 to about 5,000 as determined by vapor pressure osmometry.

The automatic transmission fluid compositions of this invention can also contain other lubricant additives known in the prior art. A brief survey of conventional additives for lubricating compositions is contained in the publications LUBRICANT ADDITIVES, by C. V. Smalheer and R. Kennedy Smith, published by the Lezius-Hiles Company, Cleveland, Ohio (1967) and LUBRICANT ADDITIVES, by M. W.

Ranney, published by Noyes Data Corporation, Parkridge, New Jersey (1973). These publications are incorporated herein by reference to establish the state of the art in regard to identifying both general and specific types of other additives which can be used in conjunction with the additives of the present invention.

In general, these additional additives include (besides the hereinbefore mentioned extreme pressure agents and dispersants) such additive types as ash-containing detergents, viscosity index improvers, pour point depresants, anti-foam agents, anti-wear agents, rust-inhibiting agents, oxidation inhibitors, corrosion inhibitors, seal swell agents and friction modifiers.

The ash-containing detergents are well known. They comprise basic alkali or alkaline earth metal salts of sulfonic- acid, carboxylic acids or organo-phosphorus-containing acids. The most commonly used salts of these acids are sodium, potassium, lithium, calcium, magnesium, strontium, and barium salts are used most extensively as compared to the others. The "basic salts" are those metal salts known to the art where the metal is present in a stoichiometrically larger amount than necessary to neutralize the acid. Potassium- and barium-overbased petrosulfonic acids are typical examples of such basic detergent salts. Ash-containing detergents can replace the above-described dispersants in whole or in part in the lubricating compositions.

Pour point depressing agents are illustrated by the polymers of ethylene, propylene, isobutylene, and poly(alkyl methacrylic). Antifoam agents include silicones, polymeric alkyl thiooxane, poly(alkyl methacrylates), terpolymers of diacetone acrylamide and alkyl acrylates or methacrylates, and the condensation products of alkyl phenol with formaldehyde and an amine.

Viscosity index improvers include polymerized and copolymerized alkyl methacrylates and mixed esters of styrene-maleic anhydride interpolymers reacted with nitrogen-containing compounds.

Viscosity index improvers may also serve as dispersants in the compositions.

When additional additives are used in the automatic transmission fluid compositions herein, they are used in concentrations in which they are normally employed in the art. Thus, they will generally be used in a concentration of from about 0.001% up to about 25% by weight of the total composition, depending, of course, upon the nature of the additive and the nature of the automatic transmission fluid composition. For example, pour point depressants, viscosity index improving agents, antifoaming agents and the like, are normally employed in amounts of from about 0.001% to about 10% by weight of the total composition, depending upon the nature and purpose of the particular additive.

The automatic transmission fluid compositions of the present invention may, of course, be prepared by a variety of methods known in the art. One convenient method is to add the additives in the form of a concentrated solution or substantially stable dispersion (i.e., an additive concentrate) to a sufficient amount of the base oil to form the desired final automatic transmission fluid composition.

This concentrate contains the additives in proper amounts so as to provide the desired concentration of each additive in the final automatic transmission fluid composition when added to a predetermined amount of a base oil.

Compositions Example I A composition suitable for use as an automatic transmission fluid, is prepared, using as the base oil, 65% poly-l -decene having viscosity of 4 centistokes at 1000C. and 35% of a 200N mineral oil, and as additives, by weight; 4% of a mixed ester of a styrene-maleic anhydride copolymer reacted with a nitrogen-containing compound (prepared as in U.S. Patent 3,702,300); 3.0% of a commercially available, proprietary seal swell agent; 1% of the reaction product of a polyisobutenyl substituted succinic anhydride, commercial tetraethylene pentamine, and boric acid prepared as in U.S.Patent 3,254,025; 0.3% of a commercially available diphenyl-amine based oxidation inhibitor; 0.1% of a dialkyl phosphite; 0.5% of a conventional friction modifier based on polyoxyethylene (2) tallowamine; 0.3% of a hydroxythioether prepared by reacting propylene oxide and t-dodecylmercaptan (prepared as in U.S. Patent 4,031,023); and 3.0% of the dispersant of Example A-i.

Example II A composition, suitable as an automatic transmission fluid is prepared using as a base oil, poly-1- decene having a viscosity of 6 centistokes at 1000C., and as additives, by weight; 2.0% of a seal swell agent; 2.8% of the dispersant of Example A5; 1.7% of a boron-containing dispersant, the dispersant base first prepared as in Example A--5 and thereafter treated with boric acid; 0.2% of a dialkyl hydrogen phosphite extreme pressure agent; 0.2% of a commercially available diphenylamine-based antioxidant; 0.3% of a sulfurized fatty ester-fatty acid-olefin mixture; and 0.5% of a hydroxythioether prepared by reacting propylene oxide and t-dodecylmercaptan (as prepared in U.S. Patent 4,031,023).

Those of ordinary skill in the art to which this invention pertains will, upon consideration of the foregoing, recognize many obvious modifications and equivalents of the invention. Such modifications and equivalents are intended to be part of this invention except to the extent they are excluded by the appended claims.

Claims

1. An oil composition comprising: (A) a carboxylate ester-free base oil comprising a major amount of a synthetic, liquid, hydrocarbon-based olefin oligomer; and (B) a minor amount of extreme pressure agent containing phosphorus and sulfur, said oil composition having a viscosity of less than about 100,000 cPs at 400 C. (according to ASTM Method D-2983), a phosphorus content of less than about 0.10 weight percent and a sulfur content of less than about 1.5 weight percent.

2. The composition of claim 1 having a viscosity of less than about 12,000 cPs at 400C.

3. The composition of claim 1 having a viscosity of less than about 20 centistokes at 1000C.

4. The composition of claim 1 wherein the base oil (A) comprises an oligomer of normal alpha olefins having about 618 carbon atoms.

5. The composition of claim 4 wherein the oligomer has a dimer content of less than 1 5 percent by weight.

6. The composition of claim 5 wherein the oligomer is of a purely hydrocarbyl olefin fraction having a mean carbon atom content of about 10 carbon atoms.

7. The composition of claim 5 wherein the oligomer is a hydrogenated oligomer.

8. The composition of claim 5 wherein the oligomer is an unhydrogenated oligomer.

9. The composition of claim 1 wherein the base oil (A) contains no more than about 10 percent by weight natural oil.

10. The composition of claim 1 wherein the base oil (A) consists essentially of a synthetic, liquid, hydrocarbon-based olefin oligomer.

ii. The composition of claim 10 wherein the oligomer is purely hydrocarbyl and of normal alpha olefins having about 6-1 8 carbon atoms.

12. A composition of claim 1 wherein the oil composition has a phosphorus content of from at least about 0.01 up to less than 0.05 weight percent and a sulfur content of from at least about 0.01 up to less than 1.0 weight percent.

13. A method of operating a manual automotive transmission which comprises lubricating the transmission with the oil composition of claims 112.

14. A manual transmission containing the oil composition of claims 112 as lubricant.

1 5. A method of operating an automatic automotive transmission which comprises lubricating the transmission with an automatic transmission fluid composition comprising: (A--l) A base oil comprising a major amount of a synthetic liquid, hydrocarbon-based olefin oligomer, and (B) A minor amount of extreme pressure agent containing phosphorus and sulfur, said automatic transmission fluid composition having a viscosity of less than about 50,000 cPs at -400C. (according to ASTM Method D-2983), a phosphorus content of less than about 0.10 weight percent and a sulfur content of less than about 1.5 weight percent.

16. A method according to claim 15 wherein the automatic transmission fluid is a composition having a viscosity of less than about 12,000 cPs at 40C C.

17. A method according to claim 16 wherein the automatic transmission fluid is a composition having a viscosity of less than about 20 centistokes at 1000C.

18. A method according to claim 17 wherein the base oil (A-i) comprises an oligomer of normal alpha-olefins having about 6-1 8 carbon atoms.

19. A method according to claim 18 wherein the oligomer is of a purely hydrocarbyl olefin fraction having a mean carbon atom content of about 10 carbon atoms.

20. A method according to claim 19 wherein the oligomer is a hydrogenated oligomer.

21. A method according to claim 19 wherein the oligomer is an unhydrogenated oligomer.

22. A method according to claim 19 wherein the base oil (A1) contains no more than about 10 percent by weight of natural or non-olefin synthetic oil.

23. A method according to claim 22 wherein the base oil (A-i) consists essentially of a synthetic, liquid, hydrocarbon-based olefin oligomer.

24. A method according to claim 15 wherein the automatic transmission fluid is a composition having a phosphorus content of from at least about 0.01 up to less than 0.05 weight percent and a sulfur content of from at least about 0.01 up to less than 1.0 weight percent.

25. A method according to any of claims 1 5-24 wherein the automatic transmission fluid composition also contains one or more lubricating oil dispersants (C).

26. A method according to claim 25 wherein the dispersants (C) are selected from the group consisting of: (C-i) High molecular weight acylated nitrogen-based dispersants; (C-2) High molecular weight ester-based dispersants; (C-3) High molecular weight Mannich-based dispersants; (C-4) High molecular weight hydrocarbyl amine-based dispersants; (C--5) Post-treated products of one or more of (C-i) through (C 4); (C-S) Interpolymeric dispersants having repeating pendant groups of up to about 24 carbon atoms; (C-7) Mixtures of two or more of any of the dispersants included in (C-i) ) through (C-S).

27. A method according to claim 26 wherein the dispersant (C) is dispersant (C 4).

28. A method according to claim 27 wherein the dispersant (C4) is a boron-containing dispersant.

29. A method according to claim 28 wherein the boron-containing dispersant is a high molecular weight acylated nitrogen-based dispersant reacted with a boron compound in an amount to provide from about 0.1 atomic proportion of boron for each mole of the acylated nitrogen-based dispersant.

30. The invention in all its novel aspects.