US2144469A - Lubricating oil - Google Patents

Description

' oils, the treatmentsometimes including oxidation nut oil and caoutchouc) employed, differ widely 20 Rial PatentNo iflszgop castor oil is subjected to the use oi colloidal grinding to homogenize 17, 1939 g Q Q 2,144,469

UNITED STATES PATENT olu-uca f t 2,144,469 4 wamcarmo on.

William E. Townsend, Brooklyn, N. Y., and Robert 0. Maxwell, Elizabeth, N. 1., assignors, by mesne assignments, to A. G. Richardson 8a 00., Inc., New York, N. Y., a corporation of New York No Drawing. Application March 31, 1938,

' Serial No. 71,879

16 Claims. (Cl. 87-9) This inve tion relates to lubricating oils, and petroleum oil. These processes do not appear to relates mo particularly to the compunding of have gone into commercial use, and it would seem petroleum lubricating oilswith non-mineral that the compounded oils produced would be unoils. 1 l I p suitable for use in modern internal combustion It haslong been recognized that petroleum engines. lubricatingoils are deficient in valuable qualities The present invention relates to yet a fourth which are found to a pronounced degree in class, in which amixture of 'castor oil and of a certain non-mineral oils, such, for example, as non-mineral oil miscible therewith and also with castor oil. Numerous attempts have been made petroleum oiL s mpl y d. as n th s nd class heretofore to blend mineral oils with castor oil above, and there is also used a comparatively 10 in an effort toobtaln a l bri ant having the adminute quantity of a stabilizing agent, which not vantages of both. Castoroil in its natural state, only tends to prevent separation-of the nonhowever, is not miscible with petroleum oils, and mineral oils from the mineral oil, but exerts an various expedients have, therefore, been devised important influence on the characteristics of the for the intended purpose of overcoming this difresultant compounded lubricating oil. So far as flculty. I we are aware, the only prior process of this gen- -In one class 01' compounded oils, reliance has eral character is disclosed in Higgins Patent No. been placed upon-heating and partial distillation 1,780,157. in wh h. h w v r. t sp fi p p of castor oil to'render itmiscible with petroleum tions and the specific stab l g agents 5- by blowing with air. Processes of this type are from those of our invention. disclosed in Dodge Patent No. 1,477,635, Rosen- According to the presen invention. a b en i baum Patent No. 1,773,203 and Clough Patent No. mp und is pr du ed whi h onsists ess ntial y 1,782,801. The difllculty with such processes has of a mixture of nonne al o ls. ncludi t rbeen that the castor oil'losesa large part of its a d a Sta zin a e t. and which is miscible lubricating characteristics during the treatment, n a l des b e proporti ns w t Pet e ub n he r sulting compounded oils have not been eating oil to improve the characteristics thereof, satisfactory inpractical us thereby producing a compounded lubricating oil A second class of compounded oils involves the whi is Stable, n on y p n long stan ing. but use of a vegetable oil,: suchas rapeseed oil or under the conditions of operation 01' modern incorn oil, which is miscible both with castor oil ternal combustion engines, and which is superior and with petroleum oil, in order to get castor oil to the petroleum 0 1 used as a a e. o n y in ts into solution in the mineral oil. Processes of this lubricating qua t in other quall Valuable class are disclosed in Banker Patent No. 255,096, p op rti s to be Pointed out below- Rice Patent No. 1,163,856 and Mackle Patent No. The stabilizing agent of our invention consists 1,677,244. While the resulting compounded oil of-a comparatively minute amount of a waterhas at first the appearance of complete solution, insoluble metallic soap, such as zinc stearate. We stratification will usually take place upon long are aware that it is not broadly novel to use such standing, and the compounded lubricating oils metallic soaps in lubricating'oils, examples of this produced are not stable or satisfactory under the being found in Doell et al. Patent No. 1,781,167 40 conditions of internal combustion engine, operaand Rosenbaum Patent No. 1,860,622, but, so far tion. Y I as we are informed, such metallic soaps have Still a third class of compounded oils comprises never been used in the manner norfor the purthose in which castor oil is subjected to a chemi- 1 Dose o o invention, I101 With oomparable cal reaction to render it miscible with-mineral sults. I v oil. In these processes, relatively large quantities Subsidiary but to some extent independent feaof the chemical reagents in proportion tothe tures of our invention relate to the specific kinds quantityuof castor oil were employed. Thus, in and proportions of the non-mineral blending oils; to the action of oi 1e-"flfthfto two-fifths of its and stabiliz compounded lub cat g o d volume of cresylic acid, and in Reizenstein Patent to the use of a naphthol to control and reduce No. 1,715,785, castor oil is treated with six per the corrosive tendencies of lubricating oils comcent by weight of aluminum sulphate. In both pounded in accordance with our invention. cases, the castor oil apparently undergoes some our invention and its objects and advantages chemical change which renders it miscible with will beclearly understood by those skilled in this art from the following detailed description thereof.

Our blending compound comprises essentially castor oil and a non-mineral oil miscible therewith and with petroleum oil, such as rapeseed oil, and a small amount of a water-insoluble metallic soap, such as zinc stearate, which acts as a stabilizer. The proportions of these ingredients may be varied over a wide range. The blending compound may be mixed with the petroleum lubricating oil which it is desired to improve in the amount of from one to fifteen percent or more by volume of the mixture. We have found it desirable to use an amount of the blending compound ranging from two to eight percent of the finished compound lubricating oil to produce an oil for use in automobile or other watercooled internal combustion engines, and from six to ten percent to produce a compounded oil for use in air-cooled aviation internal combustion engines. Moreover, we have found that the properties of the compounded oil may be improved by'including an animal oil such as spermaceti oil in the blending compound. Furthermore, when the oil is to be used in engines provided with modern alloy bearings, as distinguished from the conventional Babbitt bearings, we have found it desirable to include a small quanttiy of alpha-naphthol or beta-naphthol in the blending compound, which greatly decreases the corrosion producing tendencies of the compounded lubricating oil with such bearings.

I The following are given as specific examples of satisfactory oils produced in accordance with our invention:

Example N0. 1

Solution A (the blending oil) is prepared by mixing highly refined edible rapeseed oil and highly refined medicinal castor oil, preferably in the proportion of four parts by volume of the former to one partof the latter. The mixing is preferably accomplished by agitating and heating to a temperature of from 100 to 125 F. for fifteen minutes.

Solution B (the stabilizing agent) may be made up by adding to 16 quarts of a light neutral petroleum lubricating oil, for example one having a viscosity of 150 to 200 seconds at 100 degrees F., three quarts of Solution A, 1 pound of zinc stearate (chemically pure) and 1 quart of pure ethyl. alcohol. This mixture is agitated and heated slowly to from 300 to 400 degrees F., during which heating all or most of the alcohol is evaporated. The alcohol appears to serve as a dispersion agent and aids in getting the zinc stearate into solution in the mineral oil. The heatingis then. discontinued and 5 pounds of lanolin may be added to the still hot solution. The solution is then filtered while still warm through a one hundred mesh screen, which serves to remove and retain a small quantity of undissolved lanolin. The solution is then allowed to cool. It is faintly hazy'but appears to contain no suspended solids.

Solution C (the final blending compound) may then be prepared by mixing Solution A with Solution By in the proportion of one gallon of the former to one-half ounce of the latter.

A lubricating oil for automobile engines may be made by mixing the blending compound, Solution C, with a high grade Pennsylvania petroleum lubricating 011, preferably one that has been de-waxed by a cold settling process, in the proportion of six gallons of the blending compound to 100 gallons of the Pennsylvania oil.

The procedure that we have employed to mix the mineral oil and the blending compound involves the use of a mixing kettle of standard design heated by closed steam coils and provided with a mechanical paddle agitator and a circulating pump which draws liquid out near the bottom and sprays it back into the top of the kettle. A mineral lubricating oil of viscosity such as to produce the desired viscosity in the finished compounded lubricant (which may readily be determined by experiment), is introduced into the kettle and the agitation by means of the paddles and the circulating pump is commenced. The predetermined percentage of the blending compound is then added to the kettle, and the mixture is heated by means of the closed steam coilsto a temperature of from 100 F. to 120 F. Extreme heating of the oils is unnecessary to effect a thorough combination thereof. This heating and agitation should be continued forfrom 30 to 45 minutes when using a 700 gallon kettle filled practically to capacity with the paddles rotating at from 50 to 100 revolutions per minute and a rate of circulation through the pump from 50 to 100 gallons per minute.

During this blending operation, a considerable quantity of small bubbles is formed in the oil. While these are eliminated upon standing, we consider it preferable to perform a further operation to break down these bubbles and insure a thorough. and complete intermixture of the blending compound and the mineral oil. This we do by passing the compounded oil through a colloid mill of standard type, such as that known as the Charlotte colloid mill, having closely spaced cone-shaped members, one of which revolves rapidly with respect to the other. We have used satisfactorily spacings of from 0.005 to 0.10 inch and speeds of from 2000 to 3000v R. P. M. We believe that this colloidal grinding operation is very valuable in insuring that the compounded lubricating oil is reduced to a condition of complete homogeneity and in stabilizing the oil. It may be omitted without detriment where the oil is to be used in relatively light service, but we prefer to employ it for an oil to be subjected to heavy duty as in airplane engines.

Example No. 2

Solution A is prepared by mixing the following oils in the proportions by volume indicated as below:

Percent Highly refined edible rapeseed oil 80 Highly refined medicinal castor oil 12 Spermaceti oil (technical) 8 Solution B is prepared as described in Example No. 1, with the following ingredients and proportions:

Lightneutral petroleum lubricating oil quarts" 14 Rapeseed oil--. quarts 2 Castor oil quarts 2 Spermaceti oil quarts 2 Zinc stearate lb 1 Ethyl alcohol (absolute) quart 1 Lanolin lbs.. 5

Solution C (the blending compound) is preparedby mixing Solution.A with Solution B in the proportion of one gallon of the former to one and five-eighths ounces of the latter.

An excellent automobile lubricating oil may be made in the same manner as described under Example No. 1.

"An aviation oil that has been commercially used in this country and exhaustively tested with remarkably successful results, was made by compounding a 100% Pennsylvania. lubricating oil with Solution C above. In the table below, the properties of this oil are shown under the heading Oil No. 3, and are compared with the properties of two related oils. Oil No. 1 is a 100% Butler County, I by blending a bright stock de-waxed by cold settling and a neutral oil in such amounts asto obtain a viscosity of 100 seconds at 210 degrees F. Oil No. 2 is a different blend of the same bright stock and the same neutral oil, mixed with Solution A abovein the proportion of 92 parts by volume of the Pennsylvania oil blend to 8 parts of volume of Solution A, the amounts of the bright stock and the neutral oil being so chosen as to give, after the addition of the Solution A, the same viscosity of 100 seconds at 210 degrees F. Oil No. 3 is the same Pennsylvania oil blend as in Oil' No. 2 mixed with Solution C, in the same proportion of 92 parts of the former to 8 parts of the latter. Oil No.3 was subjected to the colloidal grinding operation described above, being passed directly from the mixing kettle to the colloid mill while still Warm and filled with air bubbles.

Table N0. 1

Property Oil No. 1 Oil No. 2 Oil No. 3

Baume gravity 28. 6 2S. 3 28. 3 Flash (F.) 490 510 510 Fire ("F.) 560 570 570 Viscosity 100 F 1,120 1,050 i, 050 Viscosity 210 F 100 100 100 Visoosity-index 104. 109 109 Film strength 8, 000 9, 400 10, 000 Coeflicient of friction 0. 110 0. 103 0. 100

In the foregoing table the first six items are all ascertained in accordance with the standard lubricating oil testing procedure. The film strengths shown in on a standard Timken testing machine, developed and made by Timken Roller Bearing Company, Canton, Ohio. The film strength is measured in terms of the number of pounds pressure between the bearing block and the test ring of the machine before seizure takes place when operating at 400 feet per minute rubbing speed. The coefiicient of friction was determined on a Herschel machine, developed by Dr. W. H. Herschel of the United States Bureau of Standards, and made by American Instrument Company, Washington, D. C. This was the improved Herschel machine introduced early in 1936, of the direct reading type provided with a variable speed drive.

The tests described herein were made at the maxi mum speed of the severe condition.

It will be noted that machine, which is the most Oil No. 2 is greatly improved in its various characteristics over the Pennsylvania Oil No. 1, and the compounded Oil No. 3 is slightly better than Oil No. 2 as to its film strength and coeflicient of friction. The principal advantages of the treatment with the stabilizing agent (Solution B), however, relate to the .stability of the oil, particularly under engine operating conditions, and this is not reflected in the data given in the foregoing table.

As above stated, this lubricating oil compoundaccording to our invention has been exhaustively tested in airplane engines under conditions of actual flying with remarkable results. It has shown an oil consumption considerably less than Pennsylvania lubricating oil made' this table were determined half of that of the standard commercial oils previously employed by the air line that made the test. At the same time, the oil displayed extremely low gum-forming and sludge-producing tendencia, produced a comparatively small amount of carbon, and the engines showed an astoundingly small amount of wear on their moving parts. The present regulations of the Department of Commerce require an airplane engine to be completely overhauled, cylinders reground, and the like, after 350 hours of operatests above referred to, which were made by special permission of the Department of Commerce, the two engines being tested have erated for 600 hours without a complete overhaul, and the tests are still being continued. The engines have, of course, been periodically partially disassembled, checked for wear, and the usual minor repairs and adjustments made, but the wear has been so slight that no complete overhaul has been indicated as necessary.

Example No. 3.

Solution B is prepared bymixing the following ingredients in the proportions indicated:

Light neutral petroleum lubricating oil qts 6 Zinc stearate 1h 1 Ethyl alcohol (absolute) qt 1 The above mixture is agitated and slowly heated up to 400 F., during which heating and agitation most or all of the alcohol is evaporated. The solution is then filtered while warm through ordinary filter paper or the like, and then cooled.

a saturated solution at room in lieu of beta-naphtha], but is-more expensive, and, hence, the latter is preferred. Both of these naphthols dissolve readily in alcohol. If not used immediately, the solution should be kept in a sealed container.

The blending compound, Solution 0, is prepared by mixing Solution A with Solutions B and 3-1 in the proportion of one gallon of' Solution A to one-half ounce of Solution Solution B-l. Solutions B'and.B1 should be added separately and one incorporated thoroughly-in the mixture before the other is added, but the order of addition is unimportant. If both are added together, a slight cloudiness will result, which is undesirable.

Anautomobile oil specially suited for modern automobile engines having alloy bearings of the cadmium silver type, which are especially subject to-corrosion by conventional lubricating oils, may be prepared by blending a hlgh grade Pennsylvania lubricating oil such as described above with Solution C in the proportions of 95 gallons of the former to 5 gallons of the latter.

The following table shows the improvement in the properties of such a Pennsylvania oil which results from the treatment above described, and the same comparative data is given as in the preceding table. Thus, Oil No. 1 is a'100% Butler County Pennsylvania lubricating oil blended from neutral oil and bright tling; Oil No. 2 is a different blend of the same stock dewaxed by cold setthe Solution B of Example ume; and Oil No. 3 is the same Pennsylvania oil blend as in Oil No. 2 mixed with Solution C in the same proportion and subjected to colloidal grinding as described above. The Pennsylvania blends were so chosen as to maintain the same viscosity at 210 degrees F. for Oils Nos. 1 and 3.

Table No. 2

Property Oil No. 1 Oil No. 2 Oil No. 3

Banm gravity- 30. 6 29. 9 29. 9

155 (F 435 450 450 Fire F.) .l 485 510 510 Viscosity at F- 410 370 360 Viscosity at 210 F. 59 60 59 Viscosity index 100 114 Film strength 7,000 8, 100 8, 500 Coemcient of friction 0. 0. 113 0. 110 Corrosion- 1. 7502 0. 8358 0. 0028 The corrosion figures shown in the foregoing table were determined on commercial cadmium silver hearings in a modified Underwood corrosion testing apparatus manufactured by Scientific Instrument Company, of Detroit, Michigan. The apparatus and the procedure used were those described in a bulletin of The General Motors Corporation Research Division, dated August 8, 1935, and entitled The Modified Underwood Corrosion Testing Apparatus. The figures above given were obtained in tests run for a period of 12 hours at a temperature of 350 degrees F. and represent the grams loss of weight of the cadmium silver bearings tested.

It will be observed that the oil compounded according to our invention, Oil No. 3, shows a phenomenal decrease in corrosion under this test, as compared either with 011 No. 1 or Oil No. 2. Were the beta-naphthol solution (Solution 3-1) to be omitted from the blending compound, Oil No.3 would still be superior to Oil No. 1 and Oil No. 2 in its corrosion producing tendencies, but the marked superiority shown in the foregoing table is due to the addition of the beta-naphthol solution. In a further corrosion test on Oil No. 3, a cadmium silver hearing was subjected to a test for 22 hours at 280 degrees F. and showed a loss of weight of 0.0028 gram. Another test of Oil No. 3 for 12 hours on a similar bearing at 325 degrees F. showed a loss of weight of 0.0008 gram. In another test of 12 hours at 350 degrees F., a cadmium silver bearing showed a loss of weight of 0.0024 gram. This bearing was then removed from the machine, a new cadmium silver bearing put in, and the oil that had already been tested for 12 hours at 350 degrees F. was run against the new bearing for an additional 22 hours at 280 degrees F. This test showed a loss of weight of the second bearing of 0.2562 gram.

Although definite proportions have been given in the foregoing three examples, it will be under-' stood that the proportions of the various ingredients may be varied within a fairly 'wide range, and that the proportions given above are merely by way of illustration. For instance, we have successfully used in formulas of the general character of Example No. 3, proportions of Solution B ranging from one-half to 2 ounces to 1 gallon of Solution A, and proportions of Solution B-1 ranging from 2 ounces to 32-ounces to 1 gallon of Solution A. v a

It will be noted that no lanolin is employed in No'. 3, and that this solution also omits" the vegetable and animal oils used in Solution B of Examples No. 1 and No. 2.

neutral oil and bright stock mixed with Solution .A above in the proportion of 95 to 5 parts by vol- Recent experiments have convinced us that this simplification of Solution B produces results equally as satisfactory as those obtained with the more complicated formulas of Examples Nos. 1

and 2. However, we have reported Examples Nos.

1 and 2 as they stand for the reason that oils made according to these formulas have been successfully used commercially. Our present belief is, however, that the lanolin contributes nothing of value to the stabilizing agent (Solution B), and that the zinc stearate may advantageously be added to the blending compound in the desired quantity simply by preparing an alcohol solution of zinc stearate in light mineral oil, as described under Example No. 3, or, highly refined edible rapeseed all might be substituted for the light mineral oil.

With respect to the various Solutions A described in the foregoing examples, it has already been noted that the proportions of the constituent non-mineral oils named can be varied within fairly wide limits. Moreover, other vegetable oils which are miscible both with mineral oil and castor oil, such as cottonseed oil, may be substituted for the rapeseed oil. We have found the latter, however, to be completely satisfactory and to be commercially feasible, and it is preferred because it has in and of itself desirable lubricating qualities'that are lacking in cottonseed oil. Furthermore, suitable substitutes for the sperm oil may be found in other animal oils or greases, such as lard oil or lanolin. We are not aware of any vegetable oil non-miscible with mineral oil having the desirable lubricating qualities of castor 011.

Our preferred composition for the non-mineral blending oils, however, is a mixture of rapeseed oil, castor oil and spermaceti oil. The spermaceti 011 gives exceptional spreading and penetrative qualities to the finished lubricant, while the castor oil and the rapeseed oil lend extra adhesiveness and oiliness. The rapeseed 011, due to its greater miscibility with petroleum oils than the other two, enables the mixture to be readily blended with petroleum oils in the needed proportions of the blending oils to the petroleum oil,

. which, as pointed out above, may be from one to fifteen percent or more of the finished compounded lubricant. We prefer to have the rapeseed oil constitute not less than 50 percent nor more than 80 percent of the mixture and to have the castor oil present to the amount of not more than 25 percent nor less than 10 percent of the total and the spermaceti oil present to the amount of not more than 25 percent nor less than 5 percent. As will be noted from the Oils Nos. 2 in the two tables given above, non-mineral blending oils within the foregoing limits are capable, when added to petroleum lubricating oils in relatively small amounts. of producing a marked improvement in their properties, even without the use of a stabilizing agent.

For many lubricating purposes, such'oils would be proportions just described is novel, and it is likewise novel to subject a compound lubricating oil to a colloidal grinding operation to render it more homogeneous and more stable. The application duce corrosion,

of these features of our invention, therefore, we do not desire to limit to compounded lubricating oils stabilized by the use of a water-insoluble metallic soap'as above described.

With respect to the stabilizing agents (Solutions B) described above, we have already noted that lanolin is not an essential ingredient. In

place of the zinc stearate, which we prefer, we-

have successfully used aluminum 'oleate, and there is no reason to doubt that zinc oleate and aluminum stearate could also be used, and per- -haps other water-insoluble metallic soaps. While we have called the zinc stearate a stabilizer, its action is somewhat obscure. It appears not only to resist the tendency of the compounded oil to separate, but also to decrease its tendency to progum and carbon, as well as to improveits lubricating 'qualities and to increase its life under engine operating conditions. This may possibly be due to some catalytic or inhibiting effect of the so-called stabilizing agent upon substances in the oil which would otherwise decompose under engine operating conditions, but as to this, we express no definite opinion.

While we have described our invention specifically in connection with the improvement of paraflin base oils, it is to be distinctly understood that our blending compound is equally useful in improving the properties of mixed base or asphaltic base lubricants, and we have successfully employed it for so doing. Furthermore, althoughour description recites the preparation of a blending compound which is thereafter mixed with the lubricating oil to be improved, and this is our preferred procedure, it is likewise possible to blend the various constituents of the blending compound directly with the mineral oil without preparing a separate blending compound as such.

Although we have described our invention specifically in the preferred embodiments now known to us, we do not desire to be limited thereto, but

desire to be limited only by the prior art and the scope of the appended claims, in which our invention and its various features are clearly and definitely pointed out.

We claim:

1. A compounded lubricating oil suitable for use g in internal combustion engines consisting princonstitutes less than cipally of petroleum lubricating oil, said petroleum oil constituting not more than 99 percent and not substantially less than 85 percent by volume of the total compound, and having in admixture therewith, castor oil, rapeseed oil and a stabilizing agent, said rapeseed oil being present in an amount considerably in excess of the amount of said castor 01], said stabilizing agent being a water-insoluble metallic soaplof the group consisting of zinc and aluminum stearates and oleates, and said soap constituting less than one percent by weight of said compounded lubricating oil.

2. A compounded lubricating oil as claimed in claim 1 in which the v in addition spermaceti oil.

3. A compounded lubricating oil as claimed in claim 1 in which said soap is zinc stearate and ,5 of one percent by weight of said compounded lubricating oil.

4. A blending compound adapted to improve petroleum lubricating oil and form a compounded lubricating; oil suitable for use in internal combustion engines by admixture therewith in prov portions ranging from one percent to fifteen percent by volume of said compounded lubricating oil, comprising castor oil, rapeseed oil and a nil admixed materials include 7 stabilizing agent, said rapeseed oil being present in an amount considerably in excess of the amount of said castor oil, said stabilizing agent being a water-insoluble metallic soap ofthe group consisting of zinc and aluminum stearates and oleates, and said soap constituting less than one percent by weight of said blending compound.

5. A blending compound as claimed in claim 4 which includes in addition spermaceti oil.

6. A blending compound as claimed in, claim 4 in which said soap constitutes less than V of one percent by weight of said blending compound.

7. A blending compound as claimed in claim 4 in which said soap is zinc stearate and constitutes less than $5 blending compound.

of one percent of said 8. A compounded lubricating oil suitable for use and not substantially less than 85 percent by volume of the total compound, and having in admixture therewith, castor oil, rapeseed oil,

and spermaceti oil, the rapeseed oil constituting not less than 50 percent nor more than percent of the total of said last three oils, the

castor oil constituting not less than 10 percentnor more than 25 percent of said total, and the spermaceti oil constituting not less than 5 percent nor more than 25 percent of said total.

9. A compounded lubricating oil as claimed in 'claim 8 that has been homogenized by subjecting it to a colloidal grinding operation.

10. A compounded lubricating oil as claimed in claim 8, and containing in addition a waterinsoluble metallic soap of the group consisting of zinc and aluminum stearates and oleates, said soap constituting less than one percent by weightof said compounded lubricating oil.

11. A compounded lubricating oil as claimed in claim 8, and containing'in' addition zinc constituting less than stearate said zinc stearate l of one percent of said compounded lubricating 12. The method of preparing a compounded lubricating oil, water-insoluble metallic soap of the group consisting of zinc and aluminum stearates'and oleates in a mixture of alcohol and petroleum oil, removing the alcohol by evaporation and mixing the resulting oil-soap solution with petroleum lubricating ofl, castor oil and rapeseed oil, in such proportions as to form a compounded lubricating oil in which said petroleum lubricating oil constitutes not more than 99, percent and not substantially less than percent by volume of the total compound, in which said rapeseed oil is present in an amount considerable in excess of the amount of said castor oil, and in which said soap constitutes less than one percent by weight of said compounded lubricating oil.

13. The method of preparing'a compounded lubricating oil as claimed in claim 12 in which said soap is zinc stearate and constitutes less than 2 of one percent by weight of said compounded lubricating oil.

14. The method of preparing a blending compound adapted to improve petroleum lubricating oil and form a compounded lubricating oil suitable for use in internal combustion engines by admixture therewith in proportions ranging from one percent to fifteen percent by volume of said compounded lubricating oil, which comprises dissolving a water-insoluble metallic soap of the which comprises dissolving agroup consisting of zinc and aluminum stearates and oleates in a mixture of alcohol and'petroleum oil, removing the alcohol by evaporation, and mixing the resulting oil-soap solution with castor oil and rapeseed oil in such proportions as to form a blending compound in which said rapeseed oil is present in an amount considerably in excess of the amount of said castor oil, and in which said soap constitutes less than one percent by weigh 10 of said blending compound. r