US3426738A - Method of operation and lubricant for closed emission internal combustion engines - Google Patents

Description

Feb. 11, 969 J. K. GOODWINE, JR 3,426,733

METHOD OF OPERATION AND LUBRICANT FOR CLOSED EMISSIQN INTERNAL COMBUSTION ENGINES Filed Oct. 16, 1967 LUBRICATING OIL cRANKCASt INVENTOR JAMES K. GOODWINQJ United States Patent 3,426,738 METHOD OF OPERATION AND LUBRICANT FOR CLOSED EMISSION INTERNAL COMBUSTION ENGINES James K. Goodwine, In, San Rafael, Califi, assignor to Chevron Research Company, San Francisco, Calif., a Corporation of Delaware Continuation-impart of application Ser. No. 580,892, Sept. 21, 1966, which is a continuation-in-part of application Ser. No. 468,517, June 30, 1965, now abandoned. This application Oct. 16, 1967, Ser. No. 681,041 U.S. Cl. 123-119 4 Claims Int. Cl. F02m 7/10; F02!) 29/02; C10m 1/32 ABSTRACT OF THE DISCLOSURE Spark ignition internal combustion engine equipped with valve-controlled positive crankcase ventilation system is operated with crankcase lubricating oil composition containing diethylene glycol monobutyl ether whereby said diethylene glycol monobutyl ether is withdrawn continuously in vapor form and introduced into the positive crankcase ventilation system. Mineral lubricating oil composition contains the combination of nitrogenous ashless detergent and ethylene glycol monoalkyl ether.

CROSS REFERENCES TO RELATED APPLICATIONS This application is a continuation-in-part of application Ser. No. 580,892, now abandoned, filed Sept. 21, 1966 which in turn is a continuation-in-part of application Ser. No. 468,517, now abandoned, filed June 30, 1965.

BACKGROUND OF THE INVENTION In recent years spark ignition, internal combustion engines have been equipped with a positive crankcase ventilation (PCV) system to reduce the fumes normally produced by the operation of such engines. This system commonly comprises a tube or other conduit connecting the crankcase to the air-fuel intake system such as the carburetor or intake manifold of the engine. Since the pressure conditions in both the carburetor and the crankcase may vary widely, it is the usual practice to connect the crankcase and intake system through a control valve orifice or other pressure control means. This control prevents abnormally high vacuums which occur from time to time during normal engine operation from imposing a vacuum on the crankcase which might pull oil along with the fumes from the crankcase.

In the normal operation of PCV systems, particularly those including control valves, the systems become plugged with carbon deposits and sludges due to the condensation of oil vapors and other materials found in crankcase fumes. This plug results in improper carburetor mixtures, causing poor idling and stalling. Also, crankcase ventilation is reduced, leading to increased engine sludge.

In the past, maintenance of PCV systems has required that the motorist either replace the valve periodically or remove it and clean it in a suitable solvent. In practice this was not often done due to the expense and inconvenience usually associated with any sort of engine overhaul, as well as lack of understanding for the need for periodic servicing.

SUMMARY OF THE INVENTION In accordance with the present invention, it has now been found that the operation of a spark ignition internal combustion engine equipped with valve-controlled positive crankcase ventilation system whereby fumes are withdrawn from the crankcase and introduced into the airfuel intake system may be surprisingly improved by the method which comprises operating said engine with a crankcase lubricating oil composition containing from about 2 to about 10% by weight of diethylene glycol monobutyl ether.

Also in accordance with the present invention, a superior new ashless detergent lubricating oil composition has been discovered which comprises a major proportion of mineral lubricating oil, a minor proportion sutficient to improve the detergent characteristics thereof of a nitrogenous ashless detergent obtained by the acylation of alkylene polyamines having from 2 to 20 carbon atoms and from 2 to 10 nitrogen atoms with alkenyl succinic acid or alkenyl succinic anhydride having from about 30 to about 400 carbon atoms in the alkenyl group and from about 2 to about 10% by weight of ethyleneglycol monoalkyl ether having 1 to 3 ethyleneglycol units and from 1 to 8 carbon atoms in the alkyl group.

By the practice of the present invention, the engine operation is greatly improved. Proper fuel-air ratios are maintained thus resulting in easier starting, better warm up without stalling and improving idling. Furthermore, good crankcase ventilation is maintained resulting in less carbonaceous or sludge type deposits on oil screens, piston rings and other engine parts. The more efiicient re moval of fumes from the crankcase also reduces the presence of corrosive materials and thereby decreases ring and cylinder wear.

The ashless detergent lubricating oil compositions of the present invention provide particularly improved opration. There is also a remarkable improvement in prevention of carbonaceous or sludge-type deposits on oil screens, piston rings and other engine parts, as well as decreases in ring and cylinder Wear.

The lubricating oil composition of the present invention is composed of a lubricating oil base and from about 2 to about 10% by weight of ethylene glycol ether, more particularly diethylene glycol monobutyl ether. Lubricating oils which can be used as base oils are preferably the class of oils known as mineral lubricating oils. The preferred crankcase lubricating oil base compositions from the standpoint of improved engine operation comprise a major proportion of mineral lubricating oil and a minor proportion sufficient to improve the detergent characteristics thereof of a lubricating oil detergent, more particularly a polymeric detergent. Usually such detergents are employed in amounts of from 0.1 to 10% by weight of the total composition. Other additives may also be present such as pour point depressants, oiliness and extreme pressure agents, anti-oxidants, corrosion inhibiting agents, blooming agents, thickening agents, foam inhibitors and/ or other compounds for enhancing the physical and chemical characteristics of the oil.

Illustrative lubricant compositions of the above type containing the glycol additives of the invention in combination with other agents may include, for example, from about 0.1 to 10% by weight of alkaline earth metal higher alkylphenate detergent and wear reducing agents, such as calcium alkylphenates having an average of approximately 14 carbon atoms in the alkyl group. Also included are organic thiophosphate corrosion and high temperature oxidation inhibitors such as the reaction product of pinene and P 8 and the bivalent metal dihydrocarbyl dithiophosphates, Zinc butyl hexyl dithiophosphate and zinc tetradecylphenyl dithiophosphate in amounts of from about 0.1 to 10% by weight of the composition. Temperature-viscosity improving agents which may be employed in the compositions, usually in amounts of from about 1 to 10% by weight, include by way of example the homopolymers of alkyl methacrylates such as the dodecyl methacrylate polymers known to the trade as Acryloid 710 and Acryloid 763, products of Rohm & Haas Company, and high molecular weight butene polymers such as Paratone ENJ P, a product of the Enjay Company.

Illustrative lubricating oil detergents for use in the preferred composition in accordance with the present invention include the nitrogenous, ashless detergents obtained by acylation of ethylene polyamines with alkenyl succinic acid or alkenyl succinic anhydride. An example of this type of detergent is the polyisobutenyl succinic acid reaction product of tetraethylene pentamine in which the polyisobutenyl group contains from 30 to 300 carbon atoms and preferably from about 40 to 200 carbon atoms. Other suitable ashless detergents include the macromolecular polyester detergents such as the copolymer of alkyl methacrylates and vinyl pyrrolidone.

The nitrogenous ashless detergents are prepared by heating the alkylene polyamine and alkenylsuccinic acid or alkenylsuccinic anhydride with the removal of water. The temperature of the reaction will generally be from about 200 to about 500 F more particularly from about 225 F. to about 400 F. The mol ratio of the polyamine to the succinic acid or anhydride will generally be in the range of from about 0.5:1 to about 1.5:1, more particularly from about 0.8:1 to about 12:1. The time for the reaction will generally be from about 10 minutes to about 12 hours or more, usually in the range of about minutes to about 6 hours. If desired, the reactants may be employed with an inert reaction medium, such as a hydrocarbon, for example, mineral lubricating oil. In such case, the concentration of the reactants may range from about 1 to 90% by weight, but will usually be from about to 75% by weight of the total reaction mixture. During the reaction, it may be desirable to remove water formed from the reaction, as for example by distillation. Subatmospheric pressures may be used for this purpose with advantage.

The amine with which the alkenylsuccinic acid or alkenylsuccinic anhydride reacted preferably has at least one primary amino group. The nitrogen atoms are joined by alkylene groups of from 2 to 6 carbon atoms, preferably of from 2 to 3 carbon atoms, except the primary amino groups will be substituted with hydrogen or lower alkyl groups of from 1 to 6 carbon atoms, more usually from.1 to 3 carbon atoms. Nitrogen atoms may be present as a heterocyclic ring.

The polyalkyl polyamine reactant is illustrated by the following general formula:

H N(ANR) [AN(CH CH N] (ANR) R wherein A is an alkylene radical containing from about 2 to 6 carbon atoms, R is a member of the group consisting of hydrogen and alkyl radicals containing from about 1 to 6 carbon atoms, x is a number from 0 to 10, y is a number from 0 to 2, and z is a number from 0 to l, the total of x+y+z being a number from 1 to 10.

Illustrative alkylene polyamines of the foregoing types are ethylenediamine, diethylenetriamine, triethylenetetramine, dipropylenetriamine, dimethylaminopropylamine, tetraethylenepentamine, N-aminoethyl piperazine, pentaethylenehexamine, nonaethy-lenedecamine, etc.

The alkenylsuccinic acid or alkenylsuccinic anhydride reactant is illustrated by the following structural formula for the anhydride:

CHrfi 0 wherein R is a hydrocarbon radical having from to 400 carbon atoms, preferably from about 50 to about 200 carbon atoms.

The R radical of the above formula, that is, the alkenyl radical, is readily obtained by polymerizing olefins of from 2 to 5 carbon atoms, such as propylene, ethylene, isobutylene, pentene, etc., and mixtures thereof. Methods of polymerization are well known in the art, e.g., US. Patents Nos. 3,024,237, 3,024,195, and 3,018,291.

The preferred acylated alkylene polyamines are the monoalkenyl succinimides of tetraethylenepentamine of the formula:

H n-orr-o wherein R is a polyolefin radical of from 30 to 200 carbon atoms and is derived from an olefin of 2 to 5 carbon atoms.

The nitrogenous ashless detergents of the lubricating oil compositions of the invention are employed in amounts sufficient to improve the detergent characteristics. Ordinarily, amounts of from about 0.1 to about 15% by weight are satisfactory for this purpose.

The ethyleneglycol monoalkyl ether is preferably the diethylene monobutyl ether. However, other glycol ethers or mixtures thereof within the aforementioned general class may be employed. Such glycol ethers include diethyleneglycol monoethyl ether (Carbitol), diethyleneglycol monomethyl ether (Methyl Carbitol), diethyleneglycol monobutyl ether (Butyl Carbitol), ethyleneglycol monoethyl ether (Cellosolve), ethyleneglycol monomethyl ether (Methyl Cellosolve), and ethyleneglycol monobutyl ether (Butyl Cellosolve).

Although the base oil in the lubricant composition of the invention is preferably mineral lubricating oil, it may be any oil of lubricating viscosity. Thus, the base oil can be a refined paraflin-type base oil, a refined naphthenictype base oil, or a synthetic hydrocarbon or synthetic nonhydrocarbon oil of lubricating viscosity. As synthetic oils, suitable examples include oils obtained by polymerization of lower molecular weight alkylene oxides, such as propylene oxide and/or ethylene oxide employing alcohol or acid initiators, such as lauryl alcohol or acetic acid. Still other synthetic oils include esters, e.g., di 2-ethylhexyl)-sebacate, tricresylphosphate and silicate esters, such as tetra 2 ethylhexyl) orthosilicate and hexa 2- ethylbutoxy)-disiloxane. For present purposes the mineral lubricating oils are preferred, since they show the greatest improvement.

BRIEF DESCRIPTION OF THE DRAWING In further illustration of the present invention, reference is invited to the accompanied drawing. This drawing represents a schematic diagram of a system for withdrawing fumes from the crankcase to the air-fuel intake system. The figure shows the body of an automobile engine with the corresponding locations of the crankcase and the lubricating oil. Also shown are the air breather 1, air cleaner 2, and dip stick tube 3. The travel of blowby, past piston 4 and piston rings 5 of one of the cylinders 6 to the crankcase, is indicated by arrows 7. Draft tube 8, in the instant illustration, is removed from the body of the crankcase as shown by dotted lines, and, in lieu thereof, adaptor 9 with check valve 10 is fitted onto the crankcase. Pipe 11 connects valve 10 with the intake system which comprises the carburetor, throttle body 12, heat riser 14, the manifold and its several branches 15. Arrows 13 indicate the path of the ventilation air arriving through breather 1 into the crankcase and thence, on becoming mixed together with the blowby, passing through valve 10 and piping 11 into the intake system at throttle body 12. The exact location of adaptor 9 and the valve 10 on the crankcase is not critical, and it may be placed closer or farther away from the location of the draft tube in which case this tube will be either non-existent as in many new engines or plugged tight, in the case of conversion of older model engines.

In the operation of the valve-controlled positive crankcase ventilation system as described above, the presence of the glycol ether in the crankcase lubricating oil composition removes and/or prevents the formation of deposits in the system, particularly in the pressure control portion. Crankcase lubricants without the glycol ether, especially in older engines where excessive blowby gases occur, are unable to prevent the deposits in conventional engine operation.

The glycol ether mixes with the lubricating oil composition with no harmful eiTect on its lubricant function, and at the same time provides a continuing source of vaporized or entrained glycol ether which minimizes the tendency of the fumes to form deposits in the ventilation system. Also, previously formed deposits are eifectively removed. Although the glycol ether over a lengthy period of time may be used up, the desired concentration in the crankcase lubricating oil composition may be maintained by the addition of more glycol ether at any time during engine operation. However, for practical purposes, operation of the engine with the crankcase lubricant containing glycol ether need not be employed all of the time since trouble-free service of the crankcase ventilation system is obtained through periodic operation with the glycol ether on an intermittent basis. A suitable period on a mileage basis is found to be on the order of 1,000 to 3,000 miles which is, incidentally, consistent with recommended lubricating oil drain periods.

DESCRIPTION OF THE PREFERRED The operation of a spark ignition, internal combustion engine with positive crankcase ventilation (PCV) em ploying a crankcase lubricating oil containing glycol ether is also illustrated in a series of tests. In the tests, a 1964 Ford car with a 6-cylinder engine was employed. A variety of lubricating oil compositions were evaluated, including acrylate, polyethyleneglycol (1800 molecular weight) methacrylate and N-aminoethyl piperazine-glycidylmethacrylate copolymer as ashless detergent in combination with zinc butyl hexyl dithiophosphate oxidation-corrosion inhibitor. Oil C was a typical MIL-L-2104B SAE 30 lubricating oil containing polyisobutenyl succinimide of tetraethylenepentamine ashless detergent, calcium petroleum sulfonate, calcium tetradecylphenate, zinc di-(tetradecylphenyl) dithiophosphate and zinc butyl hexyl dithiophosphate. Oil D was similar to Oil A except that it contained in addition about 3% of the polyisobutenyl succinimide of tetraethylenepentamine, having about 65 carbon atoms in the polyisobutenyl group. Oil E was a solvent-refined mineral lubricating oil base containing calcium petroleum sulfonate, calcium tetradecylphenate and zinc butyl hexyl dithiophosphate as detergent and oxidation-corrosion inhibitor. Oils F and G were used, conventional spark ignition, internal combustion engine lubricating oils of undetermined constitution.

The tests were carried out in general on the basis of 10 miles city-type service. In addition, a test was made with the car operating on so-called Aunt Minnie service with short trips of /2 to 2 miles with intermittent cold soaking, during which the engine was allowed to cool to ambient temperatures. In still another test the performance was evaluated on a chassis dynamometer where the car had been cold soaked at F. for 12 hours prior to adding the glycol ether. Also, the clean-up eifect of one hour of idling of the engine was determined. In each case the glycol ether was diethyleneglycol monobutyl ether, and was employed in an amount of about 3% by weight based on the total crankcase lubricating oil composition.

Briefly summarized, the essential procedure of the tests involved measuring the initial flow rate of the PCV control valve and the final flow rate, each in cubic feet per minute at 14 inches of mercury differential pressure, the latter being approximately the pressure differential (vacuum) obtained in normal engine operation with the valve closed. The test results are shown in Table I below.

TABLE I Flow rate at 14 in. Oil Net miles Type service Hg Ap, c.i.m.

Initial Final (A) Multigrade SAE 1OW-30. 10 1.80 2. 63 10 1. 35 2. 60 (B) Single grade SAE 30 l0 1. 60 2. 60 10 0. 2. 60 (C) MIL-L-2104B SAE 30---- 10 1.70 2. 65 10 1. 00 2. 60 (D) MS quality SAE 10W-30... 10 1. 70 2. 60 10 1. 20 2. 65 (E) ML single grade SAE 30-. 10 1.82 2. 65 10 1. 2.62 (E) MS single grade SAE 30.- 10 0.30 2. 50 (11)) MS multigrade SAE 10 0. 30 2. (F) Used test oil N o. 1 from 10 1. 72 2. 60

Lab Eng. (G) Used test oil No. 2 from 10 1. 40 2. 60

Lab Eng. (A) Muitigrade SAE low-30-- 7 Aunt Minnie (short 1. 55 2. 60

trips of 0.5 to 2.0 mi. in length). (A) Multigrade SAE low-30.- 7. 6 Chassis Dyna. at 1. 80 2. 60

40 F. after 12-hr. soak at 40 F. (A) Multigrade SAE 10W30 0 1 hr. of idling 1. 25 2.30

1 Clean Flow Rate at 14 In. Hg. Ap=2.60 c.f.m.

The above test results show that the PCV systems of spark ignition, internal combustion engines are markedly improved by the operation of the engine with crankcase lubricating oil compositions containing diethyleneglycol monobutyl ether. A satisfactory clean-up which returns the PCV system to practically new performance is obtained within 10 miles of operation under normal types of service. Thus, it was not necessary for the system to be removed for cleaning or replacement.

Additional tests were carried out to determine other effects of the engine operation in accordance with the lubricating oil containing copolymer of dodecylmethpresent invention employing crankcase lubricating oil compositions containing glycol ether. In these tests 4 ounces of diethylene glycol monobutyl ether were added to approximately 4 quarts of conventional detergent mineral lubricating oil, namely Oil B as described above. The gasoline was a premium grade fuel containing tetralkyl lead antidetonant. Metropolitan taxi fleet cabs were used in the tests. Five cabs without the glycol ether were evalu- Solvent ated as were cabs using the glycol ether. The cabs using Initial Final the glycol ftlger each relceived 14, 4-o1ilnce doses to the g gg glycolmonobutylether Zg i3 s in o a e on a m1 a e 1 crailkca e u neat g Sp ced qua y e g Tetrachlorethylen 1.83 1.88 basis over the test period. The vanous engine parts were Bpomobenzene 1. 1. 0 examined and deposits rated on a numerical basis of O methylene to 10, with 10 being clean. The test results are shown in 1 Clean flow rate at 14 in. Hg. Ap=2.60 c.f.m. Table H below 2 Dimethyl sulfoxide.

TABLE II Miles Rocker Rocker Cab No Glycol Cab on arm arm Valve Side Push rod Doses her mileage test cover 1 assembly 1 deck 1 cover 1 chamber 1 The above test results show that operation of actual taxi cab engines results in a substantial reduction in the formation of engine deposits. This reduction in engine deposits in turn provides reduced corrosion and decreases in ring and cylinder .wear.

In still other tests the effectiveness of various solvents in crankcase lubricating oil in removing and reducing the formation of PCV plugging deposits was evaluated in a series of simulated engine tests. These tests were carried out by maintaining a typical mixture of lubricating oil and solvent at approximately the temperature range encountered in actual engine operation during which vapors or fumes from the crankcase lubricating oil were withdrawn through an actual PCV valve of the General Motors AC type. The valves had been previously fouled and plugged in actual engine service. The results of these simulated engine tests were found to correlate well with actual engine tests.

In the tests, approximately 1,200 milliliters of oil were mixed with 80 milliliters of the solvent to be evaluated. The oil was a typical multi-grade SAE l0W-30 oil, the same as Oil A in the preceding test. The mixture of oil and solvent was placed in a two-liter round bottom flask equipped with a glass mantle heating cover and a ther mometer well. A two-hole rubber stopper was placed in the neck of the flask. One hole of the rubber stopper was fitted with the PCV valve, while the other hole was fitted with a sintered glass sparger element to diffuse and moderate the air flow. A vacuum was applied to the PCV valve causing air to enter the sintered glass diffuser and pass down over the oil and solvent mixture after which it was withdrawn through the PCV valve. The oil was maintained at a temperature in the range of about 190 to about 200 F. During the test, the vacuum was maintained at about 3 of mercury for about 2 hours and then at about 14" of mercury as in the preceding tests for about 1 hour. Each test was carried out over a period of about three hours.

Before the tests, the initial flow rates of the fouled valves were determined by placing them in a test system containing a rotameter by which the flow rates in cubic feet per minute at the 14" of mercury differential pressure were determined. After the tests, the valves were From the above tests it is seen that the glycol ether solvent as illustrated by the diethylene glycol monobutyl ether is outstanding in removing and reducing the formation of PCV plugging deposits when employed in crankcase lubricating oil in the operation of typical PCV systems. Other well known solvents including the usually effective chlorinated hydrocarbons are found to give little or no clean up.

In addition to the foregoing tests, the effect of ethyleneglycol monoalkyl ether in combination with nitrogenous ashless detergent as the sole detergent in lubricating oil compositions was determined. The lubricating oil composition is mixed with pyruvic acid at a concentration of grams of acid per kilogram of oil. The mixture is heated at 284 F. for /2 hour. After standing about 20 hours, the weight of sedimented insoluble resin formed is measured. Low values indicate good detergency, and the procedure is found to correlate with actual spark ignition internal combustion engine operation.

Using the aforementioned procedure, the addition of a typical nitrogenous ashless detergent additive package to a solvent-refined SAE 30 mineral base oil was found to give 13.4 grams per kilogram of insoluble resin, whereas the addition of nitrogenous ashless detergent in combination with ethyleneglycol monoalkyl ether actually lowered the insoluble resin formation to 8.8 grams per kilogram. This is surprising, since the presence of polyglycol ethers usually detracts from the effectiveness of detergents in lubricating oil compositions. The polyglycol ether in similarly compounded mineral oil omitting the detergent gave 67.7 grams per kilogram resin.

The nitrogenous ashless detergent additive mentioned above was polyiso-butenyl succinimide of tetraethylenepentamine having about 65 carbon atoms in the polyisobutenyl group. The compound lubricating oil composition contained 1.2% by weight alkenyl succinimide, 6 mm./ kg. zinc butyl hexyl dithiophosphate oxidation-corrosion inhibitor and 1 mm./kg. zinc di-(tetradecylphenyl) dithiophosphate oxidation-corrosion inhibitor. The similarly compounded mineral oil omitting detergent was solvent-refined mineral base oil containing 12 mm./kg. zinc butylhexyl dithiophosphate. The ethyleneglycol monoalkyl ether was the diethylene monobutyl ether and was used in an amount to provide a concentration of 3.2% by weight in the lubricating oil composition.

As illustrated above, a particular embodiment of the present invention lies in the combination of nitrogenous ashless detergent and ethyleneglycol monoalkyl ether as a new additive combination for lubricating oil compositions for spark ignition, internal combustion engines. In this new combination the weight ratio of nitrogenous ashless detergent t-o ethyleneglycol monoalkyl ether is generally from about 0.01:1 up to about 15:1 and preferably from about 0.3:1 up to about :1 for most effective engine cleanliness and PCV system operation.

While the character of this invention has been described in detail with numerous examples, this has been done by way of illustration only and without limitation of the invention. It will be apparent to those skilled in the art that numerous modifications and variations of the illustrative examples may be made in the practice of the invention within the scope of the following claims.

I claim:

1. In the operation of a spark ignition internal combustion engine equipped with a valve-controlled positive crankcase ventilation system whereby fumes are with-. drawn from the crankcase and introduced into the airfuel intake system, the improvement which comprises adding to said engine crankcase lubricating oil composition from about 2 to about percent by weight of diethylene glycol monobutyl ether, withdrawing from the crankcase continuously a portion of said diethylene glycol monobutyl ether in vapor form, introducing it into the positive crankcase ventilation system and thereby contacting said valve.

2. The operation in accordance with claim 1 wherein the crankcase lubricating oil composition contains polymeric ashless detergent in addition to the diethylene glycol monobutyl ether.

3. The operation in accordance with claim 1 wherein the crankcase lubricating oil composition contains about 3% by weight of diethylene glycol monobutyl ether.

4. In the operation of a spark ignition internal combustion engine equipped with a valve-controlled positive crankcase ventilation system whereby fumes are withdrawn from the crankcase and introduced into the airfuel intake system, the improvement which comprises operating said engine with a lubricating oil composition which is comprised of a major proportion of mineral lubricating oil, a minor proportion sufficient to improve the detergent characteristics thereof of a nitrogenous ashless detergent obtained by the acylation of alkylene polyamines having from 2 to 20 carbon atoms and from 2 to 10 nitrogen atoms with alkenylsuccinic acid or alkenylsuccinic anhydride having from about 30 to about 400 carbon atoms in the alkenyl group and from about 2 to about 10% by weight of ethyleneglycol monoalkyl ether having 1 to 3 ethyleneglycol units and from 1 to 8 carbon atoms in the alkyl group, and withdrawing from the crankcase continuously a portion of said ethyleneglycol monoalkyl ether in vapor form and introducing it intothe positive crankcase ventilation system and thereby contacting said valve.

References Cited UNITED STATES PATENTS 2,260,341 10/1944 Schott 252-52 X 2,334,158 11/1943 Von Fuchs et al 44-70 2,355,591 8/1944 Flaxman. 2,383,915 8/ 1945 Morgan. 2,489,300 11/1949 Leyda 252-52 X 2,602,048 7/1952 Michaels et al. 252-427 2,914,479 11/1959 Tom et al. 252-52 X 3,024,195 3/1962 Drummond et al. 3,173,408 3/1965 Brenneman. 3,192,910 7/1965 Coffield et a1. 123-1 3,202,678 8/1965 Stuart et al.

OTHER REFERENCES Georgie: Motor Oils and Engine Lubrication, Reinhold Publishing Corporation, New York, N.Y., copyright 1950, pp. 337-340.

AL LAWRENCE SMITH, Primary Examiner.

US. Cl. X.R.

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