US2361806A

US2361806A - Modified lubricating oil

Info

Publication number: US2361806A
Application number: US366551A
Authority: US
Inventors: David R Merrill
Original assignee: Union Oil Company of California
Current assignee: Union Oil Company of California
Priority date: 1940-11-22
Filing date: 1940-11-22
Publication date: 1944-10-31
Anticipated expiration: 1961-10-31

Description

Patented on. 31, 1944 UNITED STATES MODIFIED LUBIJOA'I'ING OIL DavidR. Men-ill, Hooreatown, N. 1.. a-ignor to Union Oil Company of California, Los Angeles,

Calif., a corporation Serial No. 868,551

No Drawing. Application November 12, 1940,

25 Claims. (Cl. 252-69) This invention relates to mineral lubricatins oils modified by the addition of constituents to impart to them special characteristics especially adapting them to severe service uses as in Diesel engines and high output aviation engines. This application is a continuation-in-part of my prior application Serial No. 292,113, filed August 26, 1939. The primary object of the invention is to avoid the deposition of resinous and varnishlike materials upon pistons and rings, to prevent the sticking of rings and the accumulation of carbon behind them, and further to overcome corrosive conditions tending to develop in the engines and capable of attacking highly corrosion-sensitive bearings 01 the copper-lead and cadmium-silver type.

Heretofore, Diesel engine oils have been produced containing metal soaps, particularly alkaline earth metal soaps and especially calcium soaps, of saponifiable organic acids, wherein the soaps have overcome the tendency to deposit resinous and varnish-like materials. However, such soaps also tend apparently to cause the formation of corrosive conditions sumciently powerful to attack copper-lead and cadmium-silver bearings. In the case of many soaps oi the character mentioned it has been desirable to include a' small proportion of free acid in order to insure adequate solution of the soap in the mineral oil, and this free acidity apparently also has contributed to the corrosiveness affecting the said highly corrosive-sensitive bearings.

Heretoiore, I have suggested the use of the calcium or similar soap of hydrogenated abietic or rosin acids for use in Diesel engine oils. This soap, like others as above indicated, tends to develop corrosive conditions in severe service engines of such magnitude as to attack copperlead and cadmium-silver bearings, and this is increased when a small proportion of the free acid is left in the soap in order to impart adequate compatibility of the soap with the 'oil when moisture is present. There is evidence that the corrosive conditions are developed by reason of catalytic eil'ect imparted 'by the soap or by the metallic element in the soap, these products being augmented by the free acid when present in the soap to impart solubility as stated.

I have discovered that the development of corrosiveness in the oils while in us can be controlled by the presence of alkaline earth metal salts of weak complex non-carboxylic acidic materials capable of combining with the stronger corrosion products or oxidation products devellubricating oil with water.

l0 phenols or of chloro derivatives of these phenols.

While these acidic materials may themselves be used as anti-corrosive agents, their calcium salts, as indicated, are preferred in that they have superior eflectivene'ss in controlling the tendency 16 of the calcium dihydroabietate to develop a grease structure in event of contact 01' the resultant Other metals, particularly the other common alkaline earth metals, barium, strontium and magnesium, and in some 20 instances aluminum and zinc,- may be used in the formation of the indicated soaps. as well as in the formation of the indicated anti-corrosive salts. A-preferred lubricating oil should have good solvent power for the soaps and salts men- 5 tioned, such as a naphthenic base mineral lubricating oil. It may further possess a natural high combined-sulfur content, such as Santa Maria Valley (California) lubricating oil, inasmuch as o the sulfur supplements the anti-corrosive activity of the anti-corrosive addition agents. Iithe oil does not have adequate solvent power for these addition agents, as when a more parafllnic oil is employed, a common solvent such as trieth- 35 ylene glycol may be necessary. In addition, high boiling chlorinated compounds such as chlorinated diphenyl, chlorinated naphthalenes or chlorinated diphenyl oxide may be introduced to improve fllm strength and to impart better solvent 0 power for lacquers and varnish-like materials.

Thus, the invention resides in lubricating oils for severe service internalcombustion engines containing small proportions of oil-soluble metal soaps of hydrogenated abietic acid, such as the 5 calcium soap thereof; in proportions to control the deposition of lacquers and varnish-like materials, together with an oil-soluble weakly acidic higher phenolic compound or an oil-soluble salt thereof capable of exerting anti-corrosive func- 80 tions in the oil while in use. In the case of the salts thereof, such as the alkaline earth metal salts, particularly calcium, these salts apparently will react with the strongly corrosive acidic materials developed upon oxidation under the 55 catalytic or other influence of the soap or the metallic constituents thereof, thereby tending to maintain a neutral condition in the oil whereby to avoid bearing corrosion. The term abietic acid" is intended to include all the rosin acids.

The invention extends further to such a lubricating oil containing also a common solvent to insure solution or retention of the soap in the oil, especially on contamination with moisture. such common solvent having adequate boiling point to be retained during use, such as triethylene glycol.

Invention resides also in the use of the described salts of phenolic materials with detergent soaps of other saponifiable acids than the described hydrogenated abietic acid, such as abietic acid and similar rosin materials, oil-soluble soaps of saponifiable fatty acids, such as chloro or phenyl-stearic acids, and of other carboxylic acids, soaps of petroleum sulfonates. and the like. The abietic acid soaps will be used ordinarily with common solvents herein described.

Mineral lubricating oil A preferred mineral lubricating oil for these purposes is a naphthenic base mineral lubricating oil such as the ordinary California type. These oils have good solvent properties for the additives and in themselves possess some solvent power for the resinous and varnish-like materials that tend to deposit upon pistons and about.

rings and valves. These oils ordinarily have a small organically combined sulfur content, for example about 0.5% whcih is non-corrosive. Where the final oil product is intended to be thoroughly non-corrosive, the oil may have a sumcient or further offsetting naturally-occurring sulfur content to overcome any corrosive tendencies on the part of the soap such as might be generated in the oil during use as by hydrolysis of the soap or by reason of the presentce of some constituent used in or with the soap such as the metal constituent in the soap. Such sulfur content also imparts additional oiliness and extreme pressure characteristics to the product, and it may be that such additional sulfur content exerts anti-oxidation effects upon the soap, because it has been observed that greater sulfur content (for example 2%) reduces the amount of deposits and produces softer deposits than smaller quantities such as 0.5% of sulfur. Such additional sulfur content-may be very desirably obtained by employing a naphthenic base oil having a high natural sulfur content wherein non-corrosive organic sulfur compounds to the extent of a sulfur content of perhaps 3% or 4% on the oil remains after ordinary refining and acid treatment of the lubricating stock. Such high natural sulfur content naphthenic base oils are Santa Maria Valley (California) oils, Smackover (Arkansas) oils, Spindletop (Texas) oils and some Mexican oils. Again such high sulfur content oils may be combined with the above mentioned ordinary California or other naphthenic base lubricating oils to increase the sulfur content of the latter and blended in proportions from as low as to as high as 50% or even approaching 100% of the high sulfur oil so as to yield a total sulfur content of as low as about 1% upwards to 4% or even higher if possible. Increased sulfur content offsets corrosive tendency resulting from the soap or other addition agent, and as a result the oiliness and extreme pressure characteristics will be greater. In addition to blending as indicated to increase the sulfur content, refined high sulfur content .so1'

vent extracts of lubricating oils may be added to oils deficient in sulfur.

Calcium dihydroabietate In practicing the present invention, I obtain on the open market an ester such as methyl esterof dihydroabietic acid. This material can be obtained from the Hercules Powder Company under the trade name Hercolyn." Apparenty, it contains two hydrogens introduced into the abietic acid molecule at the most reactive of the two double bonds of methyl abietate. This material presents the following specifications:

Purity 92%-94% ester Refractive index at 20 C 1.517 Specific gravity at 20/20 C 1.032 Acid number .1. 5 Saponiflcation number 24 Color (Lovibond-5O mm. tube) 5 amber Viscosity at 25 C 27 poise Flash point (Cleveland open cup) 183 C. Flame point (Cleveland open cup) 218 C. Vapor pressure (mm. Hg)

25 C Less than 0.01 100 C Less than 1.0 200 C 4 250 C 29 300 C 135 Boiling point 365 C.-370 C.

The following is given as a specific procedure in preparing hydrogenated abietic acid and eventually calcium or other indicated soaps thereof: 2000 grams of said methyl ester of dihydroabietic acid and 600 grams of potassium hydroxide (an excess) are commingled with 2000 ml. of glycerin, and the mixture heated with stirring to about 300 F. and then up to around 320 F. to 340 F. for five or six hours. Under these rather severe conditions, methyl alcohol distills off along with some water and a small amount of oily material, leaving a clear solution of potassium dihydroabietate in the glycerin with the excess potassium hydroxide. This mixture is dissolved in about 3 gallons of water and then shaken up or otherwise agitated with about 2 parts of petroleum ether to wash out the unsaponifled material, and the petroleum ether solution is removed. To the resultant water solution containing the soaps, an excess of 1:1 or other dilute sulfuric acid is added, whereby the water-insoluble free dihydroabietic acid separates. This free acid is then put into solution in petroleum ether or similar light solvent, either by separating from the water solution and subsequently dissolving in the solvent, or by adding the petroleum light solvent to the water mixture, agitating thoroughly to effect solution of the dihydroabietic acid in the petroleum ether and removing the resultant supernatant layer of dihydroabietic acid solution by decantation from the lower layer or water solution containing the sulfuric acid and potassium sulphate. After washing the dihydroabietic acid solution with water, the light solvent is then distilled off at elevated temperature as by means of a slow stream of gas or otherwise. The resultant free dihydroabietic acid is solid or glassy at normal temperatures, possesses an acid number between about and and Hanus iodine number which has been found to vary with different samples from 83.5 to as high as 110. The value of 110 in comparison with the theoretical figure -of 84 may may represent experimental error in the test or may indicate the presence of a limited proportion of unhydrogenated rosin acids.

Such dihydroabietic acid is dissolved in a small quantity of the petroleum lubricating oil to be used in the final product, employing temperatures of around 250 F. to effect solution. The resultant solution is then added to an additional quantity of the lubricating oil at about 120 F. in quantity sufilcient to yield an eventual concentrate of about 7% to.10% soap. To this mixture about 15% to 20% of hydrated lime based on the acid present is added, along with about 0.1% water based on the total and about /4% diatomaceous earth based on the total, the earth being employed to insure good subsequent filtration of uncombined lime. The temperature of this mixture is then raised to somewhat over 250' F. or up to about 275 F. This temperature prefer ably is held as high as possible without causing undesired darkening of the'product, 275 F. representing the practical desirable limit. The temperature condition is maintained for about three to five hours or long enough to complete neutralization to the desired extent and the formation of calcium dihydroabietate. Upon completion of the saponification operation, the temperature is raised to about 325 F. to 350 F. and the mass suiliciently dehydrated to insure against any subsequent tendency to gel. This temperature also insures easy filtration, and the solids are filtered out through a filter precoated with a small quantity of any of the well-known diatomaceous earth filter aids or the like, care being taken to avoid the use of filter aids either of character or in quantity sufilcient to eiiect removal of substantial amounts of the soap from the oil as by adsorption. The filtrate is then cooled andconstitutes an oil-soap concentrate typically of around 7% to 10% soap content which is convenient for subsequent use inasmuch as its viscosity is not too high for convenient blending. Some of the common solvent may be added as herein indicated, if desired. The final blends are affected merely by addition, at around 125 F. for example, of appropriate quantities of this concentrate to additional quantities of the selected mineral lubrieating oil to yield a desired soap content.

In addition to hydrolysis of the dihydroabietic acid methyl ester as described, I may also effect hydrolysis by heating in a pressure kettle equipped with agitators the ester with 10% aqueabout 325 F. for several hours. solution so obtained may be washed with petroleum ether to remove unsaponified material or in most cases may be converted into the calcium soap with out further purification,

Alternative to the above methods of saponifying dihydroabietic acid in the presence of all of the oil desired in the concentrate, small proportions of oil may be used such as 1 or 2 volumes based on the acids, the acids being dissolved with heat as above indicated and the hydrated lime and-indicated small proportion of water added and saponification efiected directly at temperatures of around 275F., the operation being continued until the desired extent of saponification is eiiected. This results in a sort of grease and by reason of the greater concentration, the saponification period is reduced substantially. In

orclerto obtain from this grease-like mixture a suitable concentrate, additional oil is added to ample 325 F. to 350' I". This temperature also aids filtration which may be facilitated by the addition of a small percentage of diatomaceous earth which acts to assist separation of excess lime and to clarify the rosin derivatives. This hot product may be filtered through a precoated filter as above indicated, and the concentration of soap may be as high, if desired, as will permit convenient filtration at the indicated temperature. As an alternative to filtering in either of the instances above described, it may be possible to centrifuge the materials without the employment of diatomaceous earth or other filter aid. Here also common solvent may be added if required, as herein indicated, to facilitate filtration and to insure adequate solution of the soap and for the purpose of insuring soap retention in the oil as in the presence of moisture. All of these indicated concentrates are capable of subsequent dilution to the desired soap content of around 0.6% to 1.5%, as previously indicated. such blending ordinarily occurring at temperatures of around F. to 1'1- Also, the aqueous solution of sodium or potassium soap may be converted into calcium soap by addition of an aqueous solution of calcium chloride, preferably hot. The precipitated calcium soap may be filtered and washed with warm water and dried, or the wet pulp may be added to the lubricating oil and dehydrated by heating. If the oil is not adequately clear, it may be filtered or centrifuged.

Water content In connection with preparation of these concentrates, the mentioned dehydration, to insure sufiicient stability oi. products, preferably should be such that in a concentrate containing 10% soap the water content should be well under and a 7% concentrate should be dehydrated to a water content of less than about 0.2%, in order that a final blend, such as one containing 1.33% soap, will have a water content well .under 0.05%.

-such low water content blends are resistant to gelation and are still further resistant thereto when a common solvent is added, as discussed below.

Other soaps In addition to the calcium soap of dihydroabietic acid, I may also use such soaps of the other common alkaline earth metals, magnesium, strontium and barium, andfor some purposes the aluminum and zinc soaps, and of other metals where sufilciently oil-soluble.

Again, other detergent soaps than the dihydroabietates may be employed, such as similar metal soaps of other saponifiable carboxylic acids. These may be oil-soluble or oil-dispersible fatty acid soaps such as those of phenyl stearic acid and chlorostearic acids and the like; or soapsof synthetic acids produced by the oxidation of parafiinic petroleum fractions such as of paraffin wax, petrolatum or highly parafllnic lubricating oil fractions; or rosin acid or abietic acid soaps where used with ample common solvents as herein described. Also similar soaps of oilsoluble sulfonates from petroleum and the like may be employed. These materials as individuals and their manufacture are well known in the industries and need not be described in detail.

The amounts of these soaps will be in the same order as described, or between about 0.5% and 1.5%, or in the case 01' the more readily oil-soluble or oil-dispersible soap perhaps as high as 2% to 8% where viscosit: increase is not too pronounced.

Oil-soluble anti-corrosive compounds of weakly acidic phenolic materials For the purpose of offsetting or inihibitng or controlling the formation of corrosive conditions in the blended lubricating oil during engine use, I use an anti-corrosive agent or corrosion inhibitor in the class of the higherphenols, these being weakly acidic materials. I may use either such materials themselves or salts thereof, such as the calcium salts, or salts of the metals mentioned above as usable for the formation of hydroabietic acid soaps, namely magnesium and barium, or sometimes aluminum and zinc. These phenols are also efiicacious in improving the water tolerances of the calcium or other dihydroabietate. Phenol itself is eliminated because the salts must have suflicient oil-solubility to permit the desired concentration. For this reason higher phenols are required, such as polyalkylated phenols; condensation products of alkyl phenols with sulfur dichloride, or of chloro phenol or chloro alkyl phenols (in which the chlorine substituents are in the ring) with sulfur dichloride; or sulfur dichloride condensation products of aromatic substituted phenols, such as ortho or para-phenyl phenol, or chloro derivatives of these phenols. As a particular example, the condensation'product of sulfur dichloride with paratertiary-butyl or amyl phenol or other alkylated phenol may be used. The preparation of this product will be understood by those skilled in the art, and may follow the processes described in Mikeska Patent 2,139,321. The resultant material is a di-p-tertiary butyl diphenol sulfide which apparently has the formula given hereinafter. The corresponding amyl compound may also be used. Another suitable phenolic material is that obtainable on the market under the trade name Paranox (product of Standard Oil Development Company) which is in general compounded of mixed poly-alkyl poly-phenol sulfides, that is, poly-alkyl substituted hydroxy phenyl thio ethers, containing for example, a thio ether of butyl phenolate which may be designated as bis (2-hydroxy-4-butyl phenyl) suliide. This commerical product apparently contains various materials of the following general formulas:

R(CaHsOH) S(CeH3OH) R. and

R(C6H3OH) S(C6H2OH) R.S(CH3OH) R In these formulas and similar formulas herein S in general indicates one sulfur atom, but in some molecules two or more sulfur atoms may be represented, the major proportion, however, being the preferred monosulfldes; R is an alkyl group preferably containing 4 or 5 carbons (but may contain more) which groups may be different for the different components of the mixture or may be different for the two or more benzene nuclei in one of the components. R, S and 0H may occupy any of the possible positions in the benzene rings. Conveniently, the 'alkyl groups are butyl or amyl groups such as tertiary butyl or amyl groups, mixed higher phenols, for example, petroleum refinery cresols, xylenols, etc., or tar acids from coal tar. However, with the higher poly-alkylated phenols, the character of the alkyl groups is less important and even methyl groups may be adequate. Thus, these may be used in the condensation with sulfur chloride. The materials may contain higher poly- (cHmoQsQowHm H H The calcium soaps produced therefrom may be considered as representative soaps for addi- H tion to lubricating oil according to this invention and apparently have the structural formulas:

C-GBI 04H.

In practicing the invention commercially, the salts of suitable phenolic compounds, such as the calcium salt of dibutyl or other alkyl or mixed alkyl phenol sulfides above indicated, may be formed without particular difllculty by any suitable neutralization procedure as will be obvious to the skilled chemist. For example, suitable mixed alkyl phenol sulfides now available on the market as Paranox, as above indicated, are furnished with about of a lubricating oil mixture. To this material is added an approximately equal quantity of a suitable lubricating oil, such as a naphthenic base mineral lubricating oil having good solvent properties for the phenol and for the salt to be produced. This oil mixture is then commingled with hydrated calcium oxide and a small proportion of water, followed by heating to about 300 F. with agitation for a time to insure neutralization. The resultant mixture is filtered to remove solids such as excess calcium oxide.

In order to increase the ash (i. e. calcium content), and hence the degree of neutralization, it has been found convenient first to heat only to about 200 F. to 210 F. for a time to insure complete admixture and partial neutralization, then cool to F. to F., add a small quantity in the order of 3% of 95% alcohol, and then raise to the mentioned temperature of 300 F. Use of a pressure kettle to permit attainment of 300 F. in the presence of moisture is also effective.

Neutral soaps and common solvents The calcium or other metal dihydroabietate may be readily prepared in neutral form. In order to render such neutral soap adequately soluble in the mineral lubricating oil in the desired quantities, it may be. and usually is, desirable to use a small proportion of a common solvent. In some instances the phenolic compound above deand scribed may exert a small amount of common solvent action and in those cases the amount of other common solvent may be somewhat reduced. There are many common solvents of sufficiently high boiling point to adapt them to these uses. Triethylene glycol in small amount within the limits of its oil-solubility in the presence of the soap is one. Other common solvents may be diethylene glycol, tetraethylene glycol, p-tertiarybutyl phenoxy ethanol, carbitol" (diethylene glycol monoethyl ether), butyl carbitol" (diethylene glycol monobutyl ether), phenyl "Cellosolve (ethylene glycol monophenyl ether), and similar ether-alcohol types of common solvents. These common solvents act to insure retention of the soap in the oil and to overcome gelation of the soap solution in the event of entrance of water,

Final lubricating oil product The final lubricating oil product is prepared by adding to, the selected mineral lubricating oil (preferably the indicated type of naphthenic mineral oils) the desired quantity of the selected metal soap of dihydroabietlc acid, either as such if prepared separately or as the above described concentrate in lubricating oil. Where the common solvent such as triethylene glycol is employed, this or a portion of it conveniently may be introduced into the concentrate in appropriate proportion within the limits of its solubility in the oil in the presence of the soap. Otherwise, it can be added to the mineral lubricating oil to which the soap or concentrate is added. Similarly, the desired proportion of the corrosion inhibiting or controlling higher phenolic material may be added to the mineral lubricating oil either before or after or with the addition of the soap and common solvent. Similarly, it may be introduced into the soap concentrate either with or without the common solvent. Since these phenolic materials, either as such or in the form of the indicated salts, are freely, oil-soluble, at

least in the proportions required, they will readily enter into solution in the final quantity of mineral lubricating oil or into the oil of the soap concentrate. They also have some tendency to solubilize the soaps.

With respect to the quantity of the additives, a comparatively small proportion is employed. In the case of the soap of the dihydroabietic acid, a preferred proportion to accomplish the desired result is in the order of 1%. The normal range is between about 0.6% and 1.5%, with a practical operating range of about 0.8% to 1.2%. Smaller proportions than 0.6% do not perform the desired function, and proportions above about 1.5% produce no important additional valuable result and may be inclined to increase the viscosity of the original mineral oil to a substantial and, therefore, objectionable extent. Similarly, the proportion of the higher phenolic oil-soluble material is that best adapted to perform the required result. In general, it may be said that in the order of about 1% of the material is preferable, whether it be in the form of the higher phenolic derivative itself or in the form of a calcium or other salt thereof. However, this is variable, especially as the percentage of soap is varied, between about 0.4% or 0.5% and about 1.5%. Approximately 1% of such phenolic materials serves to act as a corrosion inhibitor or anti-catalyst or possibly as a neutralizer for the more strongly acid, corrosive products produced in the engine probably by oxidation, this pro- 7| tecting eflect being in general continued by such added agent for the practical life of the lubricant. Here an optimum range is apparently between about 0.6% and about 1% or 1.2%. With respect to the common solvent, this is employed in much smaller percentage in the order of'perhaps onetenth to one-fifth the amount of thesoap which is required to go into solution in the lubricating 011 within the limits of solubility in the 011. Thus. I have found about 0.15% of triethylene glycol adequate with about 1% of a calcium soap of dlhydroabietic acid, where using about 1% of the calcium salt of a phenolic material which apparently is of the type of dibutyl diphenol sulfide of the above formulas. This latter material itself apparently has a slight solubilizlng effect upon the soap. The common solvent may in general vary from about'0.1% to perhaps as high as 0.5% if within the limits of its oil-solubility in the presence of the soap. Additional quantities appear to be neither practically beneficial nor objectionable provided the limits of solubility are not exceeded Thus a specific valuable material consisted-of an ordinary California naphthenic type S. A, E. 30 mineral lubricating oil having a viscosity of about 560 seconds Saybolt Universal at F., and viscosity index of about 15, containing 1% of the calcium soap of dihydroabietic acid produced accordingto the process here outlined,

1% of a calcium salt of a sulfur chloride condens'ation product of the type of the dibutyl or diamyl diphenol sulfide (dibutyl or diamyl hydroxy phenyl thio ether) heretoforedisclosed, 0.15% of triethylene glycol as the common solvent. In addition I have employed quantities of chlorinated materials such as chlorinated diphenyl and chlorinated naphthalenes to increase the film strength of the lubricating oil; For-example, with the composition iust above described, I have added about 1.5% of chlorinated diphenyl of approximately 65% chlorine content. Where operating with highly corrosion-sensitive bearings such as copper-lead bearings, these oils not only avoid development of corrosive conditions adequate to attack-such bearings, but they also perform the desired function of maintaining clean pistons and rings by overcoming the deposition of the resinous and varnish-like materials herein mentioned as being objectionable and as tending to result in severe service internal combustion engines such as Diesel engines and high output aviation engines.

It is sometimes desirable, as has also been indicated, to employ naphthenic oils which after refinement still contain a relatively high percentage of non-corrosive sulfur naturally-occurring in the oil, of which Santa Maria Valley lubricating oil has been indicated as one example. Such oils may contain in the order of the 2.5% to 3% or even more of such naturally-occurring sulfur, a specific example being 2.75% of such sulfur.

All of these oils act to perform functions indicated as being required and at the same time do not have their viscosity materially increased over that of the original base mineral oil by reason of the addition of the indicated proportions of added constituents. Where sulfur is present, either in the added phenolic materials as in the case of the indicated sulfides or thio ethers, or

tive eflect in promoting the development or corrosive conditions, as apparently does the metal in the dihydroabietic acid soap, or in the other detergent soaps herein described which may also be used.

In connection with the use of the phenolic materials or their salts it may be that the action is merely anti-catalytic or anti-oxidant whereby formation of corrosive conditions by oxidation is inhibited. Or, it may be that at least some or such materials react with strong acids formed to tend to maintain a condition neutral with respect to hearing corrosion. I do not wish to be bound by any theory.

I claim:

1. A lubricating oil for severe service internal combustion engines containing a small. proportion of an oil-soluble metal soap of hydrogenated rosin acids in quantity to control the deposition of resinous and varnish-like materials upon pistons and about rings, and a small proportion of an oil-soluble higher phenolic compound to control conditions corrosive to highly corrosion-sensitive bearings tending to develop in the engine while the oil is in use, the oil product being normally fluid.

2. A mineral lubricating oil for severe service internal combustion engines containing between about 0.6% and 1.5% of an oil-soluble metal soap of hydrogenated rosin acids and between about 0.5% and 1.5% of an oil-soluble higher phenolic compound adapted to overcome development of conditions in the oil while in use such as to be corrosive to copper-lead bearings.

3. An oil according to claim 1 containing a small proportion of a high boiling common solvent to insure retention of the soap in the oil.

4. A lubricating oil according to claim 2 containing a small proportion in the order of 0.1% to 0.5% of a high boiling common solvent to insure retention of the rosin soap in the oil.

5. A mineral lubricating oil according to claim.

1 wherein the content of soap and phenolic materials is insufllicent to substantially increase the viscosity of the original lubricating oil.

6. A lubricating oil according to claim 2 wherein the rosin acid soap and the phenolic compounds are employed in amount insufficient to substantially increase the viscosity of the product beyond that of the original mineral lubricating oil containing such additive materials.

7. A lubricating oil according to claim 1 containing a small proportion of chemically com-' bined non-corrosive sulfur.

8. A lubricating oil according to claim 2 wherein sulfur is chemically combined in the phenolic material.

9. A lubricating oil according to claim 1 wherein the phenolic material is present in the form of an oil-soluble metal salt thereof.

10. A lubricating oil according to claim 2 wherein the oil-soluble phenolic compound is present in the Iorm of a metallic salt thereof.

11. A lubricating oil according to claim 1 wherein the mineral lubricating oil is a naphthe'nic base oil.

12. A lubricating oil according to claim 2 containing in the order of 0.1% to 0.5% of a common solvent for the soap and oil in the form of a glycol boiling above about 250 C.

13. A lubricating oil according to claim 2 containing a small portion in the order of about 0.1% to about 0.5% 01' a common solvent for the soap and the oil in the form of an alcohol-ether boiling above about 200 C.

14. A lubricating oil comprising mineral lubricating 011 containing between about 0.6% and about 1.5% of an alkaline earth metal hydroabietate, and between about 0.4% and 1.5% of an oil-soluble alkaline earth metal salt of a higher phenolic compound, the added materials being insuflicient to impart substantial viscosity increase to the original mineral lubricating oil.

15. A lubricating oil according to claim 14 wherein the mineral oil is a naphthenic base mineral lubricating oil.

16. A mineral lubricating oil containing in the orderoi 1% of calcium dihydroabietate and in the order of 1% of a calcium salt of an oil-soluble higher phenolic compound.

'17. An 011 according to claim 16 containing a small proportion, less than about 0.5%, of an alcohol-ether common solvent for the soap and oil boiling above about 200 C.

18. A lubricating oil comprising a naphthenic base mineral lubricating oil containing between about 0.6% and about 1.5% of an alkaline earth metal dihydroabietate and between about 0.4% and 1.5% of an oil-soluble alkaline earth metal salt of a weakly acidic higher phenolic compound.

19. A lubricating oil according to claim 18 containing a small proportion, less than about 0.5% of tri-ethylene glycol.

20. A mineral lubricating oil according to claim 1 containing a small proportion of a high boiling common solvent to insure retention of the soap in solution in the oil, the content of the soap and phenolic materials being insuflicient to increase materially the viscosity of the original lubricating oil.

21. An oil according to claim 2 wherein the corrosion-controlling compound is a metal salt of an alkyl phenol thio-ether.

22. A lubricating oil for severe service internal combustion engines containing a small proportion of an oil-soluble metal soap of rosin acids in quantity to control the deposition of resinous and varnish-like materials upon pistons and about rings, and a small proportion of an oilsoluble higher phenolic compound to control conditions corrosive to highly corrosion-sensitive bearings tending to develop in the engine while the oil is in use, the oil product being normally 23. A mineral lubricating oil for severe service internal combustion engines containing between about 0.6% and 1.5% of an oil-soluble metal soap of rosin acids and between about 0.5% and 1.5% of an oil-soluble higher phenolic compound adapted to overcome development of conditions in the oil while in use such as to be corrosive to copper-lead bearings.

24. A lubricating oil according to claim 22 wherein the phenolic material is present in the form of an oil-soluble metal salt thereof.

25. A lubricating oil comprising mineral lubricating oil containing between about 0.6% and about 1.5% of an alkaline earth metal abietate, and between about 0.4% and 1.5% of an oil-soluble alkaline earth metal salt of a higher phenolic compound, the added materials being insufflcient to impart substantial viscosity increase to the original mineral lubricating oil.

DAVID R. MERRILL.

Certificate of Correction Patent No. 2,361,806. v October 31, 1944.

I DAVID R. MERRILL It is hereby certified that errors appear in the printed s ecification of the above numbered patent re uiring correction as follows: Page 2, t column, line 33, for whcih read which; ine 40, for presentce read presence; and second column, line 74, strike out may second occurrence; page 4, first column, line 6, for inihibitng read inhibiting; and second column, lines 10 to 13 inclusive, strike out the formula and insert instead the following' (CHOlO C(C lh and that the said Letters Patent should be read with these corrections therein that the id may conform to the record 'of the case in the Patent Ofiice.

Signed and sealed this 16th day of October, A. D. 1945.

[sun] LESLIE FRAZER First Assistant C ommisaioner of Patents.