US2785130A

US2785130A - Extreme pressure lubricant

Info

Publication number: US2785130A
Application number: US399597A
Authority: US
Inventors: Theodore W Langer
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1953-12-21
Filing date: 1953-12-21
Publication date: 1957-03-12
Anticipated expiration: 1974-03-12

Description

United States Patent 2,785,130 EXTREME PRESSURE LUBRICANT Theodore W. Langer, Butialo, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application December 21, 1953, Serial No. 399,597 3 Claims. (Cl. 252-372) This invention relates to an extreme pressure lubricant, and more particularly to a lead soap gear lubricant adapted for heavy duty service.

One of the principal objects of the invention is to provide an extreme pressure lubricant comprising a mineral lubricating oil compounded with a combination of extreme pressure additives so as to be unusually effective in extreme pressure properties.

Another object of the invention is to provide a lead soap gear lubricant of this type which has a high Timken value.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction With the appended claims.

The compounding of lead soap, such as lead naphthenate, with a mineral lubricating oil to produce a lubricant having improved extreme pressure properties has long been known. Likewise, it has been well recognized that organic compounds containing combined sulfur or halogen or both, wherein the sulfur or halogen is present in a so-called active form, impart extreme pressure characteristics to mineral lubricating oils. A very large number of such organic sulfur-containing compounds, organic halogen-containing compounds and organic compounds containing both combined sulfur and halogen are known for this purpose. Moreover, it has previously been suggested that a combination of an organic sulfur-containing compound of this type with an organic halogen-containing compound of this type provides a synergistic effect in enhancing the extreme pressure properties of a mineral lubricating oil. However, with the increasing speeds and torques provided by modern automotive equipment, resulting in increased bearing pressures or other rigorous service conditions on the gear teeth of hypoid gears or other instances of metal to metal contact in heavy duty service, the extreme pressure requirements for lubricants of this character have steadily risen to the point where the previously known lubricants of this type no longer were suitable in meeting the heavy duty requirements.

In accordance with the present invention, an extreme pressure lubricant of superior quality is provided by compounding with a mineral lubricating oil as a predominating or major constituent, a lead soap and an oil soluble organic extreme pressure agent selected from the group con sisting of halogenated organic extreme pressure compounds, sulfo-halogenated organic extreme pressure compounds and mixtures thereof, together with about 0.1- 3.0% by weight based on the lubricant of an aliphatic polyhydric alcohol, such as a glycol or glycerine. it has.

been found that the aliphatic polyhydric alcohol has a cooperative effect in the presence of the halogenated and sulfo-halogenated extreme pressure agents in unexpectedly and materially increasing the Timken test of the compounded oil, whereby a Timlten test of O. K. at 70 pounds or more can be readily provided.

The aliphatic polyhydric alcohol component of the lead soap gear lubricant does not exert its cooperative efi'ect in materially increasing the Timken test of the lubricant unless at least a portion of the extreme pressure agent is a halogenated or sulfo-halogenated organic compound. If the sole extreme pressure agent in the lead soap lubricant is a sulfurized organic compound such as sulfurized sperm oil, sulfurized lard oil, sulfurized oleic acid, di-

'ice

benzyl disulfide, etc., the incorporation of glycerine decreases the Timken test of the compounded oil. It is absolutely essential that the extreme pressure agent contain a portion of halogenated or sulfa-halogenated organic compound for the glycerine or other aliphatic polyhydr-ic alcohol to exert its cooperative action in increasing the Timken test.

The mineral lubricating oil, which ordinarily constitutes about 50 to 87% by weight of the lubricant, can be derived from either naphthene or parafiin base crude, and can be either residual or distillate oil or a mixture thereof, depending on the viscosity desired for the particular service conditions. For an automotive gear lubricant, a blend of a residual lubricating oil with a distillate lubricating oil has been found particularly suitable in meeting the viscosity requirements for the various grades, the proportion of residual oil being increased and the distillate oil decreased as the viscosity or grade of the lubricant is raised, while the proportions of extreme pressure additives remain essentially constant. For improved color, stability and low temperature performance, both residual and mineral lubricating oils are preferably naphthene base.

The lead soap utilized in the lubricant may be any of the Well-known oil soluble lead soaps of the higher fatty acids, naphthenic acids, rosin acids, or mixtures thereof, which possess extreme pressure properties. Typical examples of soaps of this type are lead naphthenate, lead oleate, lead menhadenate (from fish oil fatty acids), and lead resinate. Lead naphthenate is preferred for this purpose. The lead naphthenate can be prepared from naphthenic acids obtained in the refining of petroleum, particularly the naphthenic acids derived from lubricating oil fractions, although gas oil naphtheuic acids can also be employed. Moreover, the naphthenic acids can contain some non-saponifiable mineral oil which may vary up to 30% or more. A typical lead naphtheuate prepared from lubricating oil naphthenic acids having a non-sap'onifiable content of about 23 has a PbO content of roughly about 20% by weight. In the following description and claims, where lead naphthenate is specified, it will be understood that this refers to a product of this type having a PhD content of about 20%, unless the contrary appears from the text. Lead naphthenate prepared from naphthenic acids essentially freed from non-saponifiable content on the other hand will run about 30% P content; and in calculating the percentage of lead naphthenate of this type to be employed, the quantity is reduced in proportion to the ratio of the PhD content to the 20% PhD content of the typical material specified, so as to provide an equivalent PbO content in the finished lubricant.

Typical examples of the aliphatic polyhydric alcohols which exert a synergistic action on halogenated and sul fohalogenated extreme pressure agents are glycerine, ethylene glycol, diethylene glycol, propylene glycol, and other glycols and polyglycols. From the standpoint or availability and effectiveness, glycerine is preferred. Also, as pointed out hereinbelow, the addition of a small amount of water in the range of about 0.0l-0.5% in conjunction with the aliphatic polyhydric alcohol in certain cases further improves the Timken test, although the presence of water is not essential. Moreover, since these extreme pressure lubricants frequently must withstand high temperatures of the order of 250300 F. and above in service, it is generally preferred to attain the high Timken value without the presence of water in the lubricant.

Halogenated organic extreme pressure agent can be any of the well-known types of organic halogen compounds possessing extreme pressure properties, lists of which are also set forth in the U. S. Patents Nos. 2,208,163 and 2,353,170. These include halogenated and preferably chlorinated aliphatic hydrocarbons, such as paraffins, paraffin wax, foots oil, kerosene, olefins and the like; halogenated aromatic compounds including halogenated compounds of the benzene series, naphthalene, phenan threne, etc.; halogenated heterocyclic compounds, such as pyridine, quinoline, etc.; halogenated oxygen-containing organic compounds, such as fatty acids, esters, and fatty oils, and many others. Since various organic halogen compounds possessing extreme pressure properties are well. known, it is deemed unnecessary to list them in detail; it being understood that any of the known types of organic halogen extreme pressure agents are suitable for purposes of the present invention. From the standpoint of availability, economy and effectiveness, a chlorinated parafiin wax constitutes the preferred material of this organic halogen type, said chlorinated paraffin wax generally having a combined chlorine content of about 35-47% by weight. A commercially available product of this character is sold under the name of Anglamol 40 by Lubrizol Corporation. Preferably, the chlorinated paraflin wax contains a small proportion of an oil soluble corrosion inhibitor of the type disclosed in U. S. Patent No. 2,298,638, which functions to neutralize the effect of any decomposition of the chlorinated extreme pressure agent with the release of free Cl. Anglamol 40 con tains a small amount of phenoxy propylene oxide as a corrosion inhibitor of this type.

It has been found that the polyhydric alcohols of the present invention are particularly effective in raising the Timlcen test of a lead soap extreme pressure lubricant containing an oil-soluble halogenated organic extreme pressure compound. The following is listed as an example of an effective extreme pressure lubricant of this type:

Weight percent Still further improvement in the extreme pressure properties of the lubricant for heavy duty service are obtained by utilizing the polyhydric alcohol in the proportions stated above in a lead soap extreme pressure lubricant containing the oil soluble halogenated organic extreme pressure compound in combination with an oil soluble sulfurized organic extreme pressure compound. In a composition of this type, the lead soap such as lead naphthemate is employed in a proportion of about 345% by weight, the sulfurized organic extreme pressure compound in a proportion of about l-% and the halogenated organic extreme pressure compound in a proportion of about 1-10%. Typical examples of this type of extreme pressure lubricant are more particularly illustrated hereinbel'ow.

In place of or in conjunction with the organic halogen compound, there may be employed in accordance with the present invention any of the well-known oil-soluble organic extreme pressure compounds containing both combined sulfur and combined halogen. These include the various types of sulfurand halogen-containing compounds as listed in U. S. Patent No. 2,208,163, including halogenated sulfides, halogenated aromatic mercaptans, halogenated cycloaliphatic or aromatic thiocyanates and sulfo-halogenated fatty acids, esters and ethers. A very satisfactory group of compounds of this type are obtained by the sulfo-chlorination of fats or fatty oils, such as peanut oil, corn oil, soy bean oil, sperm oil, lard oil and the like. This is conventionally accomplished by reacting the fatty oil with about 1015% sulfur monochloride without added heat, followed by subsequent stabilization of the reaction product by heat treatment at temperatures of about 300-350 5., followed by neutralization of any strong acidity so that the product passes the copper strip corrosion test by passing the treated oil in contact with marble chips. The resulting'products of this type generally contain about 36% of combined chlorine and about 3 8% of combined sulfur, with the sulfur content generally running somewhat higher than the chlorine content.

In order to incorporate a higher proportion of halogen with respect to sulfur in fatty oils of this type, the fatty oil may be first chlorinated as by bubbling chlorine gas through the material at F., and the resulting chlorinated product subsequently treated with ahout 1015%" sperm oil containing roughly about 5% each of combinedsulfur and chlorine.

The organic extreme pressure compound containing both combined halogen and combined sulfur'is employed in accordance with the present invention in a proportion of about 315 by weight, along with the lead soap and the polyhydric alcohol which are utilized in the proportions previously mentioned. An example of an effective extreme pressure lubricant of this type is the following:

Weight percent Mineral lubricating oil 79.5 Lead soap 10 Sulfo-ehlorinated sperm oil l0 'Glycerine 0.5

Still further improvement in the extreme pressure properties of the liquid lead soap lubricant can be obtained by utilizing the polyhydric alcohol in conjunction with an extreme pressure mixture comprising a sulfo-halogenated organic compound and/ or a separate organic halogen extreme pressure compound in combination with a sulfurized organic compound. in order to attain the highest type of extreme pressure lubricant for heavy duty service, it has been found that a combination of the three different types of the foregoing organic sulfur, organic halogen and organic sulfur and halogen extreme pressure agents are used in a lead soap lubricant of this type containing the polyhydric alcohol. This is more particularly illustrated in the examples which follow.

The oil soluble organic sulfur extreme pressure compounds, which may be used in conjunction with the halogenated organic extreme pressure agent or sulfohalogenated organic extreme pressure agents, can be any one of the known extreme pressure agents having combined sulfur, lists of which are disclosed in the aforementioned U. S. Patents 2,208,163 and 2,353,170. These include organic sulfides and disulfides, mercaptans, mercaptoles, esters of thio and dithio acids, sulfones, sulfone amides and xanthates, the organic compounds being either aliphatic, cycle-aliphatic, or aromatic. A typical example of an aromatic sulfur-containing compound which is highly effective in combination with halogenated or sulfohalogenated organic extreme pressure agents is dibenzyl sulfide. From the standpoint of availability and effectiveness, sulfurized fatty acids, sulfurized fatty acid esters and sulfurized fatty oils such as sulfurized oleic acid, sulfurized'methyl linoleate, sulfurized lard oil, and sulfurized sperm oil are commonly used in conjunction with the halogenated or sulfo-halogenated organic extreme pressure agents to increase their effectiveness.

'As has been indicated previously, an aliphatic polyhydric alcohol is effective in increasing the Timken value of lead soap gear lubricants containing an extreme pressure agent which is a mixture of chlorinated organic compound and/ or a sulfo-halogenated organic compound in combination with sulfurized organic extreme pressure agents. However, as will be illustrated hereafter the addition of glycerine or other aliphatic polyhydric alcohol to lead soap a an gear lubricants containing a sulfurized organic compound as the sole extreme pressure agent decreases the Timken test of the lubricant.

It is a characteristic of the polyhydric alcohols of the present invention that they are only sparingly soluble or incompletely soluble in the mineral lubricating oil in the proportions employed. A portion of the polyhydric alcohol is maintained in fine dispersion or colloidal suspen sion in the extreme pressure lubricant, being stabilized by the other extreme pressure additives and the lead soap. Where .the polyhydric alcohol is employed in the upper range of proportions listed, it is found that a portion of the alcohol may settle out on long standing. However, the effectiveness of the polyhydric alcohol in materially increasing the Timken test of the compounded oil remains unimpaired, since there appears to be suflicient of the material remaining in solution and colloidal suspension at all times; and alcohol which settles out may be readily redispersed when the lubricant is subjected to agitation and circulation in service.

In addition to the foregoing ingredients, a small proportion of an anti-foam agent is preferably incorporated in the lubricant. A very satisfactory material of this type is a silicone polymer, such as a dialkyl, diaryl or alkylaryl silicone polymer of known anti-foam properties. A typical material of this type is dimethyl silicone polymer having a kinematic viscosity at 25 C. of about 100-1000 centistokes. The silicone polymer is conveniently handled as a concentrate in a hydrocarbon solvent, such as kerosene. In the specific examples which follow, the concentrate was prepared by dissolving dimethyl silicone polymer in kerosene in the proportion of 10 grams of the polymer with sufiicient kerosene to make up to a volume of 100 ccs. The anti-foam agent, such as the silicone polymer concentrate, is employed in the lubricant in the proportion of about 0.001-0.0l5% by weight, preferably about 50 parts per million.

In addition to the foregoing ingredients, it is to be understood that the extreme pressure lubricant may also include small proportions of known anti-corrosive agents, pour depressants, viscosity index improvers, oxidation inhibitors, dyes and the like. Moreover, effective compositions in accordance with the present invention may include proportions of the order of l5% of a fatty oil or ester having lubricity improving properties, such as menhaden oil, lanolin, sperm oil and the like.

In order to illustrate the eifectiveness of various polyhydric alcohols in raising the Timken test in accordance with the present invention, the following is listed as typical of results which have been obtained. The extreme pressure'lubricant base (omitting polyhydric alcohol) had the following composition:

Percent by weight Mineral lubricating oil 80 Lead naphthenate l Anglamol 40 3 Benzyl disulfide 2 Menhaden oil 5 To the foregoing base composition, various polyhydric alcohols were added in a proportion of 1% by weight, and the resulting lubricants together with the base composition subjected to the standard Timken test with the following result:

Since glycerine represents the preferred material from the standpoints of effectiveness, availability and cost, the following examples employ this particular polyhydric alcohol. However, it is to be understood that other polya hydric alcohols may be substituted therefor with highly satisfactory results.

In order to illustrate the effect of various proportions of the polyhydric alcohol in the lubricant, the following example is listed as typical of test results which have been obtained. The particular extreme pressure lubricant base composition employed in this test had the composition as listed above in connection with Table I. To this composition, glycerine was added in various proportions, and the resulting lubricants together with the base composition subjected to the standard Timken test with the following results:

It has been heretofore suggested that various oxygencontaining organic materials including monohydric alcohols, and particularly the high molecular weight oilsoluble monohydric alcohols such as wool fat alcohols, be included in an extreme pressure lubricant. The following Table 111 sets forth the results obtained upon the addition of the specified oil-soluble materials containing hydroxy groups to the base lubricant composition of Table II, in comparison to the results obtained by the addition of glycerine to that composition:

Table III Concen- Timken Test tration, Material Percent by Wt. O. K., Lbs/sq. in.

Lbs.

Glycerine 1 60 19, 250 Sperm Oil. 5 5O 14, 500 D0 10 35 12,500 Wool Grease 5 35 12, 500 Do 10 40 14, 000

The foregoing results show that the oil-soluble materials containing monohydric alcohols and esters thereof are not the equivalents of the polyhydric alcohols of the present invention, which latter are incompletely soluble in the extreme pressure lubricant.

It has further been found that a small percentage of added water, in addition to the polyhydric alcohol, in a lead soap extreme pressure lubricant containing the organic halogen and/0r organic sulfo-halogenated extreme pressure agents, may effect further increase in the Timken test of the lubricant. This is illustrated in the following Table IV, where the base extreme pressure lubricant composition undertest consisted of the follow- Weight Percent Mineral lubricating oil 86 7 Lead naphthenate 10 Anglamol 40 3 Glycerine 1 The foregoing composition was modified by the addi compositions together with the base composition subjected to Timken't ests with the following results:

Table IV Timken Test Water Added, Percent by \Vt.

Lbs/sq. in.

The following Table V illustrates the efiect or various proportions of an organic halogen extreme pressure agent in a base lubricating composition consisting of mineral lubricating oil containing 10% by weight of lead naphthenate and 1% by weight of glycerine.

Table V V Tinilcen Test Chlorine, Percent Anglamol 40, Percent by Wt. by Wt. in 0. K., Lbs/sq. in. Lubricant Lbs.

The foregoing table indicates that the optimum percentage of the chlorinated paraffin Wax additive in an extreme pressure lubricant of this character is about 34% by weight. The effect of the polyhydric alcohol, such as glycerine, in increasing the Tirnken value of a lubricant of this type consisting of a mineral lubricating oil containing 10% by Weight of lead naphthenatc and 3% of Anglamol 4-0, is evident from the following comparative tests. Thus, the base lubricant containing no glycerine had a Tirnlien O. K. test of 50 pounds, and a p. s. i. test of 16,250 and 18,000. When 1% glycerine was added to this base lubricant, the Timken' test was 0. K. 70 lbs, with a p .s. i. test of 21,750 and 20,500.

The following table illustrates the effectiveness of various extreme pressure lubricant compositions containing lead soap and glycerine with chlorinated and sulfochlorinated fatty oils alone and in combination with sulfurized fatty oils.

Table VI Percent by Wt.

Ingredients:

Mineral Lubricating Oil- Lead Naphtbenate OhlorinatedPeanut Oil. Sulfurized Menhaden Oil zClz Treated Peanut Oil Glycerine Timkenlest:

10 O. K., Lbs LbsJSq. In

8 tive. The base composition employed consisted of the following:

Mineral lubricating oil weight percent. 77

Lead naphthenate do. 10 Sulchlor do 10 Anglamol 40 'do 3 Dimethyl silicone polymer concentrate p. p. m 50 To the foregoing composition, different percentages of glycerine and water were added,'and the resulting compositions subjected to Tirnken tests in comparison to the base composition, and also to a heat stability test wherein the lubricant was maintained 'at an elevated tempera: ture of 250 F. for four hours and the quantity of precipitate settling out was measured. The following Table Vii sets forth the results obtained.

Table VII i Glyccr- Water, Timkon Test inc, Vt. .h Heat Stability Per- Tosh-Depth Percent cent 0. K., Lbs/sq. of Frecipitate Lbs. in.

None None Score As in. white precipitate. 0 5 90 {41,000 P4 in. gray r 28, 500 precipitate. 0.1 Score 70. As in. white 3 9 q $preciplifate. ..,..5\ in. w ite l 90 g3, i9 precipitate. is in. w itc 90 i n: 000 precipitate. 1.0 c0 393,28 Do.

41 500 %u in. white 90 2a500 precipitate. 0.3 90 Do. 0.2 ss Do.

Y 18,500 Mn in. white 25, 250 precipitate.

The mineral lubricating oil employed in the immediately foregoing compositions of Table VII was a blend of a parafiin base residuum which had been propane deasphalted and centrifuge dewaxed, with a paraffin base distillate lubricating oil of SAEZO grade; The table shows that a proportion ofglycerine as low as 0.1% has a pronounced effect on increasing the Timken test of the compounded oil; and that concentrations of glycerine as low as 0.3% without added water are effective to provide a Timken O. K. value or. this lubricant of pounds. While the lubricant shows some sedimentation in the heat stability test, this appears largely attributable to the use of the more highly refined parafiin base lubricating oils in the formula, and can be eifectively overcome by the employment of a naphthene base residual-distillate blend as discussed hereinbelow.

To the foregoing base composition of Table VII containing 1% by weight of glycerine and 0.1% of added water, the following organic sulfur'and sulfo-chlorinated extreme pressure agents were also added and Timken tests obtained on the resulting compositions, as shown in Table VIII.

In the foregoing table, the composition containing the sulfurized sperm oil contained only 0.5% glycerine and no added water, as distinguished from the other compositions of the table which contained 1% glycerine and 0.1% added water. The other materials of all compositions listed were the same as set forth for the base composition of Table VII, except that the Weight percent of mineral lubricating oil was reduced according to the amount of sulfur-containing or sulfo-chlorinated compound added. The table shows that various organic sulfur extreme pressure agents can also be added to the base compositions while still retaining the high Timken values, and that sulfurized sperm oil is particularly effective for this purpose.

The adverse efiect of glycerine on the Timken value of a lead soap gear lubricant containing a sulfurized organic compound as a sole extreme pressure agent was shown by the following data. An extreme liquid pressure lubricant was prepared with the following composition:

Mixed base residual lubricating oil ....weight percent..- 35.0 Mixed base distillate lubricating oil do 48.3 Lead naphthenate ..do 11.7 Sulfurized sperm oil do 5.0 Dimethyl silicone polymer concentrate parts per million-.. 50

fiiflicient glycerine was incorporated in the above mixture to yield another lubricant containing 99.5% of the aforedescribed components and 0.5% glycerine. On comparison of the base composition and the glycerinemodified composition in the Timken test, the base composition showed a Timken O. K. value of 27 pounds, and 11,121 p. s. i., while the glycerine-modified composition had a Timken O. K. value of 17 pounds and 9,700 p. s. i. This data clearly demonstrates that the extreme pressure agent must contain a substantial portion of halogenated or sulfurhalogenated extreme pressure compound for the glycerine to exert its action on the Timken value of the lubricant.

A lead soap gear lubricant containing critical proportions of lead naphthenate, sulfo-chlorinated sperm oil, chlorinated paraffin wax and sulfurized sperm oil which enabled the lubricant to pass the extremely rigorous requirements of U. S. Army specification 2-105B (now designated as M1L-L-2105) is disclosed and claimed in the copending application of Samuel J. Sokol and William 10 J. Coppoc, Serial No. 186,918 filed September 26, 1950, now Patent No. 2,701,237, dated February 1, 1955.

This application is a continuation-in-part of my co pending application, Serial No. 175,482, filed July 22, 1950, now abandoned.

0bviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A lead soap extreme pressure liquid lubricant comprising as the essential ingredients a mineral lubricating oil as the predominating constituent, about 3 to 15% by weight based on the lubricant of lead naphthenate as the sole metal soap in the lubricant, about 1 to 25% by weight of an oil-soluble organic extreme pressure agent selected from the group consisting of chlorinated paraffin wax containing about 35-47% by weight of combined chlorine, sulfa-chlorinated sperm oil containing about 46% of combined sulfur and about 4-6% of combined chlorine, and mixtures thereof, and about 0.1 to 3.0% by weight of added glycerine effective to increase the extreme pressure properties of the said lubricant.

2. An extreme pressure lubricant according to claim 1, in which the extreme pressure agent is a mixture of 1- 10% by weight of said chlorinated parafiin wax and 315% by weight of said sulfo-chlorinated sperm oil.

3. An extreme pressure lubricant according to claim 2, wherein the glycerine is present in a proportion of 0.5 to 1.0% by weight.

References Cited in the file of this patent UNITED STATES PATENTS 2,136,391 Miller Nov. 15, 1938 2,179,062 Smith et al. Nov. 7, 1939 2,208,163 Prutton et al. July 16, 1940 2,255,085 Prutton et al. Sept. 9, 1941 2,264,319 Lincoln et al. Dec. 2, 1941 2,338,613 Zimmer Jan. 4, 1944 2,701,237 Sokol Feb. 1, 1955 OTHER REFERENCES Journal of the Inst. of Petroleum, April 1946, pages 209 and 210.

Performance of Lubricating Oils by Zuidema, Reinhold Pub. Co. 1952, page 15.

Claims

1. A LEAD SOAP EXTREME PRESSURE LIQUID LUBRICANT COMPRISING AS THE ESSENTIAL INGREDIENTS A MINERAL LUBRICATING OIL AS THE PREDOMINATING CONSTITUENT, ABOUT 3 TO 15% BY WEIGHT BASED ON THE LUBRICANT OF LEAD NAPHTHENATE AS THE SOLE METAL SOAP IN THE LUBRICANT, ABOUT 1 TO 25 % BY WEIGHT OF AN OIL-SOLUBLE ORGANIC EXTREME PRESSURE AGENT SELECTED FROM THE GROUP CONSISTING OF CHLORINATED PARAFFIN WAX CONTAINING ABOUT 35-47% BY WEIGHT OF COMBINED CHLORINE, SULFO-CHLORINATED SPERM OIL CONTAINING ABOUT 4-6% OF COMBINED SULFUR AND ABOUT 4-6% OF COMBINED CHLORINE, AND MIXTURES THEREOF, AND ABOUT 0.1 TO 3.0% BY WEIGHT OF ADDED GLYCERINE EFFECTIVE TO INCREASE THE EXTREME PRESSURE PROPERTIES OF THE SAID LUBRICANT.