US3274820A

US3274820A - Test for engine oil contamination

Info

Publication number: US3274820A
Application number: US332356A
Authority: US
Inventors: Julius M Komarmy
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1963-12-23
Filing date: 1963-12-23
Publication date: 1966-09-27
Anticipated expiration: 1983-09-27

Description

Sept. 27, 1966 J. M. Kon/:ARMY 3,274,820

TEST FOP?- ENGINE OIL CONTAMINATION Filed Dec. 25. 1963 l l l v 0 e a I ATTO 5)/ United States Patent O 3,274,320 TEST EUR ENGINE UIL CONTAMNATIGN Julius M. Komarmy, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Dec. 23, 1963, Ser. No. 332,356 3 Claims. (Cl. 73-61) The present invention relates generally to a method of testing for the presence of solids contamination in lubricating oils. More particularly, the present invention relates to methods of measuring the degree of solids contamination in a lubricating oil, such as is present in the cranlccase of an automobile internal combustion engine, to determine -if the oil should be replaced.

` As is Wellaknown, lubricating oil used in automobile internal combustion engines and similar devices must be replaced due to the contamination of the oil from internal sources `after various periods of engine operation and lubricant use. The contamination may -be due to a number of factors. Small insoluble dust and dirt particles are absorbed or picked up from the `atmosphere and various engine parts which contact the oil. Also, the oil chemically deteriorates or degrades because the oil molecules a-nd the various additives, such as detergents, used in modern-day engine lubricating oils, tend to oxidize and polymerize during use to form oil-soluble resinous material or complex molecular particles of varying size colloidally suspended in the oil. =In addition, insoluble fuel gums, lmetallic residues from fuel additives and products of incomplete fuel oxidization, such as carbon particles, also contribute to the contamination of an engine oil. These various contaminating substances are commonly referred t-o as solids contamination, since they may be separated from the oil by centriftuging techniques.

Of course, the presence of the aforementioned contaminating substances in the oil has a very detrimental effect on the lubricating qualities of the oil and engine operation. For instance, when the oil becomes contaminated with relatively large amounts of resinous matter and solids particles, its lubricity characteristics are detrimentally affected due to the increase in the viscosity of the oil and the abrasive character of the entrain/:d

solids particles. Also, the insoluble solids contaminants in the oil usually form sludge deposits on various engine parts, which are very detriment-al to engine operation. Thus, it is generally desirable to change the lubricating oi-l in the internal combustion engine of an automobile or other vehicle When the solids `contamination content of the oil exceeds about 3%. -by Weight, of the oil.

It Will be appreciated, of course, that some vehicle engines may be satisfactorily lubricated with oils containing greater than 3%, by weight, `solids contamination Without necessitating an oil change. Conversely, in other engines, the degree of solids contamination in the oil must be appreciably less than 3%, by Weight, in order to achieve satisfactory engine lubrication and operation. ,Consequentlyg the limit of 3%, by IWeight, solids contamination in engine lubricating oils is arbitrary. However, 1 have found that most commonly used lubricating oils for use in automobile engines preferably should be replaced when this limit is exceeded to obtain maximum engine performance.

Usually, the determination as to Whether an automobile engine lubricating oil should be replaced is made by observing the color of the oil. l-f the color of the oil has darkened considerably due to the contaminati-on of the oil, visual inspection of the oil indicates that it should be replaced. Of course, this visual inspection technique is a relatively inaccurate guide as to the necessity for replacing the oil, due to the inherent human error ele- Patented Sept. 27, 1966 ICC ment in judging the degree of contamination of the cil. Consequently, costly and unnecessary replacement of automobile engine lubricating oil is frequently made by a vehicle operator.

In the past, various scientific techniques of testing engine oils for the presence and degree of solids contamination, such as solvent extraction and centrifuging have been employed. However, these tests arel often rather time consuming and usually require special equipment, such as centrifuges, which are relatively expensive. Also, some of these methods are rather complicated and require special training in chemical analysis technique on the part of the motorist or service station attendant in order to satisfactorily perform the test. Thus, it is desirable to provide a simple, inexpensive, scientific method to accurately determine the degree of contamination of an automobile engine lubricating oil vvllich can quickly and easily be .performed by the vehicle operator or by a service station attendant to ascertain if the oil should be changed.

Therefore, it is a principal object of the present invention to provide la simple, `inexpensive testing kit which may be used to test lubricating oils, such as the type used in internal combustion engines, for the solids contamination content of the oil to determine if the oil is sufliciently contaminated to Warrant replacement.

=It is another object of the present invention to provide a simple, inexpensive method for determining the degree of solids contamination in an engine lubricating oil, such as is used in automobiles and other vehicles, which can quickly and easily be performed by the automobile operator or a service station attendant to ascertain Whether the engine lubricating oil should be replaced in an autobile or -other vehicle.

These and other objects are accomplished by placing a small quantity of the contaminated lubricating oil to be tested on the surface of Ia liquid medium contained; in a transparent bottle or vessel. The properties of the liquid medium are such that it is substantially immiscible with the contaminated oil 'and less dense than the oont-aminated oil so that the oil Will sink las a droplet in the liquid medium. By observing the capacity of the oi-l to sink in the liquid medium and relating it to a known standard, a determination of the solids contamination content of the oil may be made, thereby indicating Whether the lubricating oil is suiliciently contaminated to Warrant replacement.

As will hereinafter be more fully explained, the present invention contemplates two embodiments which function in accordance with the general procedure described above but which vary in other respects. 'In the first einbodiment of the subject invention, the liquid medium may consist of mineral oil or similar liquid in which a drop of pure lubricating -oil will dissolve, but a drop of contaminated oil Will sink :at a rate which is indicative of the degree of solids contamination of the oil. In this embodiment, the rate of descent of the contaminated oil droplet is observed to determine if the oil is suiciently contaminated to Warrant replacement.

In the second embodiment of the present invention, the liquid medium may comprise an alcohol-Water solution or similar liquid lwhich is substantial-ly immiscible with the lubricating oil and has a certain specific gravity such that a sample droplet of the contaminated lubricating oil will sink in the liquid medium only if the solids contamination content of the oil exceeds a predetermined degree of solids contamination, but will float. in the liquid medium if the solids contamination content of the oil droplet is not greater than the predetermined degree of contamination. lIn this embodiment, the capacity of the contaminated oil droplet to either float or sink in the liquid medium is observed to determine if the lubricating oil is suiciently contaminated to warrant replacement.

Other features and advantages of the present invention will be apparent from the following description of certain embodiments thereof taken in conjunction with the accompanying drawing, in which:

FIGURE 1 illustrates a simple testing kit which may be satisfactorily used to perform the lubricating oil contaminati-on test in accordance with the present invention.

FIGURE 2 is a qualitative graphical illustration of the irst embodiment of the subject invention in which the rate of descent of a droplet of contaminated lubricating oil in a liquid medium is related to the degree of solids contamination of the oil; and

FIGURE 3 is a qualitative ygraphic illustration of the second embodiment of the invention in which the capacity of a droplet of contaminated lubricating oil to sink in a liquid medium is related to the specific gravity Iof the liquid medium.

Referring to FIGURE l of the drawing, the testing kit may consist of a small bottle 12 or vessel which may be made of glass or other suitable transparent material, such as polyethylene. The rubber bulb dropper 14 may be used to place a small quantity of the contaminated lubricating oil to be tested on the surface of the liquid medium 16 contained in the bottle. The dropper has a cap portion for sealing the liquid medium in the bottle. In the aforesaid rst embodiment, the bottle preferably is indexed -or graduated, as shown at 18, whereby the rate of descent of the contaminated oil droplet may be measured by a stop watch or other suit able timing device, as will hereinafter be more fully explained.

A-s previously mentioned, this first embodiment operates Ion the principle that a droplet of pure 0r relatively uncontaminated lubricating oil will dissolve in a liquid medium of a certain type, such as mineral oil, which is also less dense than the lubricating oil, but a droplet of contaminated lubricating oil will be substantially immiscible in the liquid medium and will sink at a rate which indicates the degree of solids contamination of the lubricating oil. It is believed that the immiscibility of contaminated lubricating oil in a liquid medum, such as mineral oil, is due to the fact that the solids particles in the contaminated oil exert cohesive forces on the lubricating oil molecules which prevent the dispersion and dissolution of the oil from globule form when it is placed in the liquid medium.

In the preferred form of the aforesaid rst embodiment, .pure mineral oil U.S.P. grade is employed as the liquid medium, since it has the desired property of being substantially immiscible with most commonly used grades of lubricating oils which are contaminated with solids particles up to about one percent, by weight, of the oil. Also, it is less dense than most commonly used grades of lubricating oils which are used in automobile internal combustion engines. Other liquids, such as glycerol or any refined petroleum base product, which possess these desired properties also may be used to perform the subject oil contamination test of the present invention.

It should be appreciated, of course, that one type of oil which has the same degree of solids contamination as another type of oil will not sink at exactly the same rate in a particular liquid medium if the specific gravity of the two types of oils in their pure states differ. Also, the rate of descent of droplets of the same contaminated oil in two dierent types of liquids will vary if the specific gravity of two types of liquid mediums differ. Consequently, the subject test is empirical and the rate of descent of a contaminated droplet of a specific type of oil in a specific liquid medium must be related to an established standard in order that the test may properly the rates of descent of droplets of specific contaminated lubricating oils, such as a used SAE lO-W-lO engine lubricating oil, in a specic liquid medium, such as mineral `oil. This may be conveniently accomplished by taking several samples of the oil, each of which is contaminated to a different degree with insoluble solids particles, placing droplets of the various samples on the surface of the liquid medium and measurin-g the time req-uired for each droplet to sink through a certain distance in the liquid medium. The degree of solids contamination of the several oil samples may be measured by any suitable technique, such as the Pentane Insolubles Test and Benzene Insolubles Test as set forth in ASTM Test Procedure No. D-893T entitled Tentative Method of Test for Insolubles in Used Lubricating Oils as revised and approved in 1960.

In accordance with the above procedure, FIGURE 2 of the drawing graphically illustrates in a qualitative man ner a typical curve which may be established by plotting the rates of descent of droplets of contaminated oil in a liquid medium versus the percent, by weight, solids contamination of the oil droplets. The rate of descent may be expressed in terms of time, i.e. minutes, since the distance through which the contaminated oil droplets sink in the liquid medium is constant. It will be noted that the rates of descent of the contaminated oil droplets and the degree of solids contamination of the oil are not directly proportional but the rates of descent decrease progressively faster as the degree of solids contamination of the oil is increased.

A specific example of the first embodiment of the subject invention comparing the time required for several sample droplets of an SAE lO-W-3O engine lubricating `oil, each of which is contaminated with solids particles to a different degree, to sink through a distance of about one inch in pure mineral 'oil U.S.P. .grade is listed in Table I below. The percent solids contamination of the oil was determined in accordance with the Pentane Insolufbles Test Procedure as set forth in ASTM D-893-T.

TABLE I Percent by Weight Solids Contamination of Time, in Minutes, for SAE 10W30 Engine Lubricating Oil Droplet of Oil to Descend in Mineral Oil USP. Grade Droplet Dissolved. Droplet Dissolved. 24.

As previously mentioned, the dropper bottle 12 preferably is indexed or graduated, as shown at 18, in FIG- URE 1 of the drawing, so that the time of descent of the contaminated oil droplet may be accurately measured with a stop watch or other suitable timing device. The index markings may be suitably positioned on the bottle by duplicating the conditions used to establish the standard values for rate of descent and degree of solids contamination for `a specific lubricating oil in a specic liquid medium by the procedure described above. For example, an upper and lower index mark one inch apart might be placed on the bottle containing pure mineral oil U.S.P. grade to test SAE l0-W-30 engine oil, thereby duplicating the conditions used in reference to Table I above.

The subject test may quickly and easily be performed by an automobile operator or service station attendant using the test kit 10 to determine if the engine lubricating oil in the operators automobile is suiciently contaminated to warrant replacement. ln performing the test, a

sample droplet of the oil is taken with the dropper 14 and placed on the surface of the liquid medium 16 contained in the bottle 12. The time for the contaminated oil droplet to sink in the liquid medium between the 'upper and lower index markings is then measured. Of course, the relationship between the rate of descent of that particular type of oil in the particular liquid medium in the bottle must be known. This can be ascertained from a chart in which this relationship is set forth. For instance, if the chart sets forth the relationship as shown in FIGURE 2 of the drawing, and the contaminated oil droplet is observed to take two minutes to sink the meas- :ured distance through the liquid medium, it can readily be ascertained from the chart that the solids contamination content of engine lubricating oil is about 3%, by weight, as illustrated by point A in FIGURE 2.

As previously mentioned, the second embodiment of `the present invention operates on the principle that a droplet of lubricating oil is substantially immiscible in a liquid medium of a certain type, such as an ethyl alcohol-water solution, so that the droplet of oil will oat when its specific gravity is less than the specific gravity of the particular liquid medium used in the subject test, but will sink when its specific gravity exceeds that of the liquid medium. Of course, the specific gravity of the lubricating oil is directly related to the degree of solids contamination of the oil. Thus, in accordance with the second embodiment, the bottle 12 is filled with a liquid medium 16 having a certain specic gravity so that a droplet of the contaminated lubricating oil to be tested will sink in the liquid medium only when the solids contamination content of the oil exceeds a predetermined degree of contamination which would warrant replacement of the oil. A sample droplet of the lubricating oil to be tested is thenA placed on the surface of the liquid medium and observed to determine whether the oil droplet floats or sinks. If the oil droplet sinks, the lubricating oil is suiciently contaminated to warrant replacement, since the oil droplet will float if its solids contamination content is not in excess of the predetermined degree of contamination.

As is well known, water and ethyl alcohol have distinctly different densities and surface dimensions but are miscible in practically all proportions while being substantially immiscible with most commonly used lubricating oils. Also, a droplet of almost any commonly used engine lubricating oil will float in water but will rapidly sink in alcohol due to the differences in the specific gravities of the three liquids. Thus, a solution of ethyl alcohol and water may readily be prepared which has a certain specific gravity such that a sample droplet of lubricating oil having a certain predetermined degree of solids contamination will just sink in the solution, if the concentration of the alcohol in the solution or the degree of solids contamination of the oil is increased slightly.

Hence, we have found that ethyl alcohol-water solutions are particularly suitable for use as the liquid medium, and the known standard to which the capacity of the oil droplet to sink may be related in performing the subject test in accordance with the second embodiment of the invention. Also, the specific gravity of an ethyl alcohol-water solution may easily be adjusted to meet the desired test results, as Will hereinafter be more fully explained. In the preferred form of this second embodiment, a solution of distilled water and regularly denatured ethyl alcohol, such as is commercially marketed under the trade name Solex by United States Industrial Chemicals Company is used. Of course, other liquid materials or solutions, such as methanol, having the above-mentioned properties in relation to lubricating oils comparable to ethyl alcoholwater solutions may be satisfactorily used to perform the test.

It should be appreciated that different types of lubricating oils, such as SAE l0-W-1O and SAE 10-W-30 oils,

have diderent specic gravities in their pure states. Hence, a droplet of one type of lubricating oil which is contaminated with solids particles may float in a liquid medium, such as an ethyl alcohol-water solution having a certain specific gravity, but another denser type of lubricating oil which is contaminated to the same degree with solids particles will sink in the same liquid medium. Also, different lubricant suppliers use different additives in the same grade of lubricating oil which also affects the specific gravity of the oils in their pure state. Consequently, in performing the subject test in the eld, the type of oil which is being tested preferably should be known so that a liquid medium may be used which has the appropriate specific gravity for testing that particular type of oil lfor solids contamination in excess of a predetermined degree of contamination.

For instance, if a particular type of internal combustion engine lubricating oil, such as an SAE lO-W-SO oil, should be replaced when the oil is contaminated with solids particles in excess of about 3%, by weight, of the oil, the liquid medium which is employed in the second embodiment must have a specific gravity such that a droplet of the oil will just sink in the liquid medium when the degree of solids contamination of the oil is at least about 3%, by weight. In other words, the specific gravity of each liquid medium used in performing the subject test must be standardized for each type of lubricant which is tested for solids contamination.

This may be conveniently accomplished by conducting tests on various samples of different types of lubricating oils, each of which is contaminated to a certain degree of solids contamination. The degree of solids contamination of the samples may be measured by any suitable technique, such as the Pentane Insolubles Test and the Benzene Insolubles Test as set forth in ASTM Test Procedure No. D-893-T. An ethyl alcohol-Water solution may then be prepared for each oil sample and the concentration of the alcohol adjusted so that the specific gravity of the solution is such that the sample oil droplet will just sink in the solution. Thus, a standardized solution for testing various types of lubricating oils for a predetermined degree of solids contamination may readily be prepared.

FIGURE 3 of the drawing graphically illustrates in a qualitative manner the relationship between the specic gravity of a typical liquid medium and the degree of solids contamination of a typical lubricating oil used in performing the subject test in accordance with the second embodiment. The curve on the graph represents the capacity of a sample droplet of the contaminated lubricating oil of a certain degree of solids contamination to just sink in the liquid medium having a certain specific gravity. For instance, point B on the curve indicates that a certain lubricating oil which has a solids contamination of 3%, by Weight, will just sink in a certain liquid medium having a specific gravity of 0.89.

It will be noted that this relationship between the specie gravity of the liquid medium and the degree of solids contamination is essentially a straight line function. This is generally true of most commonly used lubricating oils, since the capacity of a contaminated oil droplet to sink in a liquid medium is directly related to the: specific gravity of the oil which in turn is essentially directly proportional to the degree of solids contamination of the oil. Table II below lists a specific example of the second modification of the present invention in which sample droplets of a contaminated SAE l0-W-30 oil, each having a different degree of solids contamination, will just sink in specitc solutions of distilled water and denatured ethyl alcohol. The degree of solids contamination of the samples of lubricating oil was measured in accordance with the Pentane Insolubles Test Procedure as set forth in ASTM D-893-T.

TAB LE II Speciiic Gravity of Alcohol-Water Solution Percent, by Weight, Solids Contamination in SAE -W-30 Engine Lubricating Oil Similar results may be obtained for other types of lubricating oils, although they will vary somewhat depending on the specific gravity of the oil and the liquid medium which is used.

The subject test may quickly and easily be performed by an automobile operator or a service station attendant using the testing kit 10 to determine if the engine lubricating oil in the operators automobile is suiliciently contaminated to Warrant replacement. The test is conducted by placing a sample droplet of the engine lubricating oil With the dropper 14 on the surface of the appropriate liquid medium 16 contained in the bottle 12. Of course, the liquid medium must have the proper specific gravity for use with the particular type of lubricating oil which is being tested so that the droplet Will just sink in the liquid medium if its solids contamination content is in excess of the predetermined degree of contamination which would Warrant replacement of the oil in the motorists automobile. The droplet of -the contaminated oil is then observed -to determine if it sinks or floats in a liquid medium. Thus, if the droplet of oil sinks, the lubricating oil is suiciently contaminated to Warrant replacement.

While I have described my invention in terms of certain preferred embodiments and specific examples, it is not to be limited thereby, and it should be understood that other variations may be apparent to those skilled in the art and are Within the intended scope of the invention as defined by the following claims.

I claim:

1. A method of `testing -a lubricating oil for the presence of solids contamination in excess of a predetermined degree of contamination which warrants replacement of said oil, said method comprising the steps of placing a droplet of the contaminated lubricating oil to be tested into a liquid medium, said liquid medium being substantially immiscible with said oil and having a speciiic gravity such that said droplet will oat in said liquid medium when the degree of solids contamination of said lubricating oil is not greater than said predetermined degree of contamination, but said droplet will sink in said liquid medium when -the solids contamination content of said droplet exceeds said predetermined degree of contamination, the sinking yof said droplet in said liquid medium indicating that said oil is sufficiently `contaminated to warrant replacement, and observing the capacity of said oil to sink in said liquid medium.

2. A method of testing an automobile engine lubricating oil for the presence of solids contamination in excess of a predetermined degree of contamination which Warrants replacement of said oil, said method comprising the steps of placing a sample droplet of the contaminated lubricating oil to be tested into a transparent bottle containing an alcohol-Water solution, said solution being substantially immiscible With said oil and having a specific gravity such that said droplet will oat on said solution when the degree of solids contamination of said oil is not greater than said predetermined degree of contamination, said droplet having a specific gravity greater than said solution when the solids contamination of said oil is in excess of said predetermined degree of contamination so that said droplet will sink in said solution, and observing the capacity of said oil to sink in said solution to determine if said oil is sufliciently contaminated to Warrant replacement.

3. A method of testing an :automobile engine lubricating oil for the presence of solids contamination in excess of about 3 by weight, of said oil, said method comprising the steps of placing a sample droplet of said oil into a transparent bottle containing a solution of ethyl alcohol and distilled water, said solution being substantially irnmiscible with said oil, said oil droplet having a specific gravity less than the specific gravity of said solution when the degree of solids contamination of said oil droplet is not greater than about 3%, by Weight, of said oil so that said oil droplet will float in said solution, said oil having a spe- 'cic gnavity greater than the specific gravity of said solution When the degree of solids contamination of said oil exceeds about 3%, by weight, of said oil so that said droplet of said oil will sink in said solution, and `observing the capacity of said oil to sink in said liquid medium to determine if the solids contamination of said `oil exceeds 3%, by Weight, of said oil.

References Cited bythe Examiner UNITED STATES PATENTS 270,489 1/ 1883 Schubert 73-61 1,600,250 9/1926 Sartakofr 73-57 2,471,861 5/1949 Cahn 23-253 X OTHER REFERENCES Guthrie: Journal of Lab. land Clinical Medicine, Reprint of Article An Apparatus for Quickly Measuring The Specific Gravity of Body Fluids, August 1932, pp. 1, 3, 4, 5, 6, 7.

DAVID SCHONBERG, Primary Examiner.

Claims

1. A METHOD OT TESTING A LUBRICATING OIL FOR THE PRESSURE OF SOLIDS CONTAMINATION IN EXCESS OF A PREDETERMINED DEGREE OF CONTAMINATION WHICH WARRANTS REPLACEMENT OF SAID OIL, SAID METHOD COMPRISING THE STEPS OF PLACING A DROPLET OF THE CONTAMINATED LUBRICATING OIL TO BE TESTED INTO A LIQUID MEDIUM SAID LIQUID MEDIUM BEING SUBSTANTIALLY IMMISCIBLE WITH SAID OIL AND HAVING A SPECIFIC GRAVITY SUCH THAT SAID DROPLET WILL FLOAT IN SAID LIQUID MEDIUM WHEN THE DEGREE OF SOLIDS CONTAMINATION OF SAID LUBRICATING OIL IS NOT GREATER THAN SAID PREDETERMINED DEGREE OF CONTAMINATION, BUT SAID DROPLET WILL SINK IN SAID LIQUID MEDIUM WHEN THE SOLIDS CONTAMINATION CONTENT OF SAID DROPLET EXCEEDS SAID PREDETERMINED DEGREE OF CONTAMINATION, THE SINKING OF SAID DROPLET IN SAID LIQUID MEDIUM INDICATING THAT SAID OIL IS SUFFICIENTLY CONTAMINATED TO WARRANT REPLACEMENT, AND OBSERVING THE CAPACITY OF SAID OIL TO SINK IN SAID LIQUID MEDIUM.