CA1205451A

CA1205451A - Glycerol esters with oil-soluble copper compounds as fuel economy additives

Info

Publication number: CA1205451A
Application number: CA000426360A
Authority: CA
Inventors: Phillip W. Brewster; Clinton R. Smith
Original assignee: Imperial Oil Ltd
Current assignee: Imperial Oil Ltd
Priority date: 1982-04-22
Filing date: 1983-04-21
Publication date: 1986-06-03
Also published as: EP0092946A3; JPS58191795A; DE3376016D1; JPH0377837B2; EP0092946A2; EP0092946B1

Abstract

ABSTRACT OF THE DISCLOSURE

Lubricating oil compositions are disclosed exhibit-ing improved fuel economy which contain 0.05 to 0.2 wt. % of a glycerol partial ester of a C16-C18 fatty acid and 5 to 500 ppm of copper in the form of an oil-soluble organic copper compound, the two components exhibiting a combined effect in improving fuel economy of internal combustion engines.

Description

S45~

This invention relates to lubricating oil composi-

2 tions which exhibit marked improvements in fuel economy. More

3 particularly, this invention relates to lubricating oil com-

4 positions which contain very minor proportions of a glycerol fatty acid ester fuel economy additive in combination with an 6 oil-soluble organic copper compound.
7 It is a current objective of the industry to provide 8 lubricating oil compositions which exhibit improvements in 9 fuel savings in gasoline and diesel engine vehicles. To meet that current goal, a new category of additives commonly refer-11 red to as fuel economy additives are being developed which 12 function primarily to increase the miles or kilometers obtained 13 per unit volume of fuel. Since modern day lubricating oil 14 compositions are complex Eormulations, such additives must be compatible with the other components of such compositions and 16 should not adversely affect the numerous other functions of 17 conventional lubricant additives such as dispersancy, vis-18 cosity stability, corrosion and oxidation inhibition, and the 19 like.
Illustrative of recent patents reflecting develop-21 ments in this field are U.S. Patents 4,201,684 and 4,208,293.
22 These patents show the use of fatty acid amides and sulfurized 23 amides as additives which have fuel economy benefits as demon-24 strated by friction reducing data.
The present invention concerns the use of glycerol 26 fatty acid esters as such fuel economy additives, specifically 27 glycerol es1:ers of C16-C18 fatty acids in combination with oil-28 soluble copper organic compounds. There is prior art disclosing 29 the use of each of these materials in lubricating oil composi-tions which is discussed hereinbelow.
31 British Application 2097313A, published November 10, 32 1982, discloses the use of 0.05 to 0. 2 w1:~6 glycerol partial 33 esters Of C16-C18 fatty acids as fuel economy additives. ~he 34 present invention is an improvement over said British applica-tion.
36 West German Application P-2949940 and P-2949910 of ~.b . .`'i ~5~

1 Chevron Research Company, both published July 3, l9aO, disclose 2 the use of glycerol ~atty esters as ~uel economy additives.
3 These references state that the addition of 0.25 to 2 weight 4 percent, preferably 0.40 to 1.25 weight percent, of a fatty acid ester will offer a fuel economy credit of 2-3 percent in both 6 gasoline and diesel engines. Glycerol oleic acid esters are 7 preferred. ~est German Application P-2949940 illustrates the 8 preferred embodiment showing the use of the glycerol ester at 9 the same ~reat level in combination with zinc dihydrocarbyl dithiophosphate additives. Similarly U.S. Patent 4,304,678 11 discloses hydroxyl-containing esters including glycerol ole-12 ates as being effective friction modifiers only at levels of 1-13 4 wt% with no benefit observed at levels less than 1~ by wt. in 14 oil.
In contrast to the teachings of these references, the 16 present invention is based upon the discovery that very low 17 levels of glycerol esters; that is, up to about 0.2 percent by 18 weight, in combination with certain amounts of oil-soluble 19 organic copper compounds, provide enhanced performance of these fuel economy lubricating oils. No benefit is obtainable 21 in using relatively higher amounts and in some cases sub-22 stantial debits in terms of formulation stability ox adverse 23 performance may occur.
24 Another reference disclosing the use of polyol-carboxylic acid esters in lubricating oil compositions is U.S.
26 Patent 3,933,659, which shows a multi-component ~unctional 27 Eluid, one component of which can be a polyol ester friction 28 modifier or a fatty acid amide friction modifier. The primary 29 us~ disclosed in that re~erence is for automatic transmission fluids. U.S. Patent 3,273,981 discloses antiwear additives 31 comprising a mixture of dimer acids and a partial ester of a 32 polyhydric alcohol, the additive being noted as improving 33 lubricity as well as ~unctioning in the anti-wear category.
34 U.S. Patent 3,112,271 discloses glycerol mono-oleate as an extreme pressure additive as does U.S. 3,112,269 and U.S.
36 3,041,284. U.S. 2,493,483 discloses marine engine lubricants 37 which contain a partial ester of glycerol or other polyol fatty 1 acid esters in amounts of from 0.05 to 1 percent.
2 Other re~erences disclosing polyol esters of fatty 3 acids are represented by U.SO 2,788,326, which discloses these 4 compounds as being useful in extreme pressure lubricants and U.S. Patent 2,527,889, which shows the same polyol esters, such as glycerol monooleate, being useful as anti-corrosion agents 7 in turbine oils and diesel fuels.
8 The use of oil-solu~le copper compounds at levels of 9 about 5 to 500 parts per million (ppm) of copper by weight, based on the total weight of lubricating oil composition,as a 11 highly effecti~e antioxidant is a relatively recent develop-12 ment of additive technology and is disclosed in European 13 Published Application No. 0024146, published on February 25, 14 1981.
The present invention is based on the discovery that 16 these copper compounds, when used in an oil in combination with 17 glycerol esters, e.g. oleates, act cooperatively with the 18 glycerol ester in substantially increasing the fuel economy of 19 the formulated oil. The cumulative effect observed would not be expected by adding the fuel economy credit obtained in oils 21 which contain one or the other of the glycerol ester or copper ~2 compound. Data obtained therefore provide the basis for an 23 unexpected additive effect upon fuel economy due to more 24 effective lubrication of an internal combustion engine oper-ated using the oils of the present invention.
26 The prior art also recognizes that copper components 27 per se can be favorable friction reducing agents in certain 28 circumstances. German Democratic Republic Patents 145,469 and 29 145,470 disclose the reduction of wear and friction in iron/iron and iron/bronze friction interfaces using polyol or 31 mineral oil lubricants containing copper compounds such as 32 copper naphthenate, copper octoate, copper stearate and reac-33 tion products of lubricants themselves with copper, copper 34 oxide and copper salts of inorganic acids. These references indicate that the friction reduction is achieved by deposition 36 on the substrate being lubricated of a film reaction layer of 37 copper with adequate adhesion properties. It is recommended in ~ Q~

1 these references that the concentration of the copper compound 2 in the lubricant provide a copper content of 0.001 to 5 volume 3 ~ relative to the lubricant. These references however did not 4 evaluate lubricating oil compositions for internal combustion engines.
6 In accordance with the present invention, there are 7 provided fuel economy improving lubricating oil compositions 8 for internal combustion engines which comprise an oil of 9 lubricating viscosity and, as the fuel economy additive, a combination from 0.05 to 0.20 weight percent of a glycerol 11 partial ester of a C16-Clg fatty acid with from 5 to 500 ppm 12 (parts per million) copper present in the form of an oil-soluble 13 copper compound, preferably about 60 to 200 ppm copper being 14 present, based upon the weight of the total composition, the copper compound also functioning as an antioxidant.
16 The lubricating oil compositions of the present 17 invention comprise both straight grade and multigrade lubri-18 cating oil formulations for both gasoline and diesel (compres-19 sion ignition) engines. Thus, in the practice of the present invention the lubricating oil compositions will contain those 21 additive systems formulated to meet the viscosity requirements 22 or other specifications as required for qualification as a 23 gasoline engine or diesel lubricating oil. A straight grade 24 lubricating oil formulation will normally contain conventional amounts of an ashless dispersant, a normal or basic metal 26 detergent, an anti-wear additive and an antioxidant and a 27 multi-~rade oil will contain, in addition to the foregcing, a 28 viscosity ind~x improver or viscosity modifier. In addition to 29 these pri~cipal additives, very small proportions of other special puxpose additive~, such as pour depressants, rust 31 inhibitors, anti-foamants and the like are conventionally 32 blended into lubricating oil compositions.
33 The ester component of the fuel economy additive of 34 the present invention is preferably a glycerol mono- or di~
ester of a saturated or unsaturated C16-C1g fatty acid, such as 36 oleic or linoleic acid. Optimum efficiency has been found to ~2~

1 be at about the 0.1 to 0.2 weight percen~ level and use in the 2 excess of this amount may even be detrimental to the overall 3 performance of the lubricating oil composition.
4 Oil-soluble copper components useful herein include S both cuprous or cupric compounds which are oil-soluble under 6 normal blending conditions in the oil additive package. Parti-7 cularly preferred ar~ the copper salts of C10-C22 fatty acids~
8 such as stearic or palmi~ic acid, but copper salts of un-9 saturated acids, such as oleic acid, linoleic acid, naphthenic acid of 200-500 molecular weight or synthetic carboxylic acids 11 are preferred. The particularly preferred embodiment is copper ~2 ~cupric) oleate when present in an amount to provide about 100 13 to 150 ppm copper in the lubricating oil composition.
14 Other suitable cop~er compounds include the same as thos~ disclosed in said European Published Application 0024146 16 and these include copper dithiocarbamates of the formula 17 ~RR'NCSS)nCu where n is 1 or 2 and R and R' are the same or 18 different Cl-Clg hydrocarbyl radicals, preferably C2-C8 alkyl, 19 copper sulphonates, coppex phenates and acetyl acetonates as well as copper dihydrocarbyl dithiophosphate, the hydrocarbyl 21 being Cl-Clg and preferably C2-Cg alkyl, such as a hexyl or iso-22 octyl.
23 Crankcase oil formulations to which the present ~4 invention relates are those which contain a major amount of lubricating oil and effective amounts of conventional ad-26 ditives in addition to the aforesaid fuel economy additive, the 27 copper compound serving the dual function of being both an 28 antioxidant and, in combination with the glycerol oleate, a 29 fuel economy additive. Percentages of additives as described herein are by weight based on the total weight of lubricating 31 oil formulation unless otherwise indicated.
3~ These conventional additives comprise ashless dis-33 persants typically nitrogen-containing dispersan~ additives 34 which are oil-soluble salts, amides, imides and esters made from high molecular weight mono- or di-carboxylic acids and ~s~

1 various amines having an amino or heterocyclic nitrogen with at 2 least one amido or hydroxy group capable of salt, amide or ester 3 formation. Preferred are the reaction products of polyolefin 4 (C2-Cs olefin), such as polyisobutenyl, succinic anhydride with an alkylene polyamine such as tetraethylenepentamine. The 6 polyisobutenyl portion has between 50 and 250 carbon atoms. The 7 alkylene polyamines are those represented by the formula:
8 NH2(cH2)n(NH(cH2)n)m-NH2 9 where n is 2 to 3 and m is a number from 0 to 10. Mixtures of alkylene polyamines which approximate tetraethylenepentamine 11 are commercially available materials. Dispersants are used 12 generally in amounts of from about 0.1 to 10 wt.%, preferably 13 in the range of about 0.5 to 5 wt %, based on the weight of the 14 lubricating oil composition.
Detergents useful in the formulations include the 16 normal, basic or overbased metal, that is, calcium, magnesium 17 and so forth, salts of petroleum naphthenic acids, petroleum 18 sulfonic acids, alkyl benzene sulfonic acids, alkyl phenols, 19 alkylene-bis-phenol, oil-soluble fatty acids and the like. The preferred materials are the normal or overbased calcium or 21 magnesium phenates, sulfurized phenates and/or sulfonates, and 22 these metal-containing detergent additives are typically used 23 in amounts of from 1 to 3 wt ~ based on the total weight of 24 lubricatin~ oil compositions.
Suitable pour point depressants, which are usually 26 present in amounts of about 0.01 to 1 wt~, include wax 27 alkylated aromatic hydrocarbons, olefin polymers and copo-28 lymers, acrylate and methacrylate polymers and copolymers.
29 Anti-wear additives gene~ally are the oil~soluble zinc dihydrocarbyl dithiophosphates having a least a total of 31 5 carbon atoms, the alkyl group being preferably C2-C8. These 32 are typically present in amounts of from 0.01 to 5 wt. ~, 33 preferably 0.5 to 1.5 wt. %, in the lubricating oil.
34 Suitable conventional viscosity index improvers, or viscosity modifiers, are the olefin polymers such as poly-36 butene, ethylene-propylene copolymers, hydrogenated polymers ~L2~5~

1 and copolymers and terpolymers of styrene with isoprene and/or 2 butadiene, polymers of alkyl acrylates or alkyl methacrylates, 3 copolymers of alkyl methacrylates with N-vinyl pyrrolidone or 4 dimethylaminoalkyl methacrylate, post-grafted polymers of e-thylene-propylene with an active monomer, such as maleic anhy-6 dride, which may be further reacted with an alcohol or an 7 alkylene polyamine, styrene-maleic anhydride polymers post-- 8 reacted with alcohols and amines and the like. These additives 9 are used in amounts of about 1.5% to 15% by wt., depending on the exact viscosity specifications desired.
11 Conventionally used antioxidants include phenols, 12 hindered phenols, bis-phenols, sulfurized phenols, catechol, 13 alkylated and sulfurized alkylated catechols, diphenylamine, 14 alkylated diphenylamines and phenyl l-naphthylamines, alkyl and aryl borates, phosphites and phosphates, trialkyl and 16 triaryl dithiophosphates and the like.
17 Suitable hydrocarbon base stocks are those mineral 18 oils of lubricating viscosity as measured by ASTM D-455 of from 19 about 2 to 40, preferably 5 to 20 centistokes at 99C.
These conventional additives are used in amounts 21 noxmally necessary to provide their attendant functions in a 22 formulated crankcase lubricating oil composition. Very small 23 proportions of additional special purpose additives, such as 24 anti-foam agents or rust inhibitors, may also ~e present in a fully formulated lubricating oil composition.
26 The invention is further illustrated by the follow-27 ing Examples.

29 The reference oil used in this example was a formula-ted straight grade 20W30 crankcase mineral lubricating oil 31 (corresponding to ASTM "HR" oil) to which was added 0.2 weight 32 percent of a glycerol monooleate (GMO) fuel economy additive or 33 0.2 weight percent of a fuel economy additive being a mixture 34 (GMO/GDO) of glycerol monooleate and glycerol dioleate in a weight ratio of 3 parts of GMO to 2 parts of GDO in said mixture.
36 The reference oil contained 2.10 wt ~ dispersant, 1.10 wt. %

~2C)S~S~

antioxidant, 1.00 wt. % basic metal detergent, 1.95 wt. % anti-2 wear additive, 0.21 wt ~ pour depressant and 0.001 wt. % anti-3 foam agent. This type of reference oil, which is generally 4 accepted by the industry for establishing fuel economy data, provides a reproducible baseline against which fuel economy 6 credits may be measured and is considered to provide test 7 results which accurately reflect the effect of a given fuel 8 economy additive.
g Fuel economy was evaluated using the Laboratory Engine Fuel Economy Test (LEFET) summarized below:
ll The fuel economy test used is a fired engine pro-12 cedure. The engine is a 5.0 liter, V~8 Chevrolet engine coupled 13 to a water ¢ooled electric dynamometer. The engine is run with 14 a dry sump by the use of external oil pumps. One pump supplies oil to the oil gallery from an external sump and a second pump 16 scavenges the sump and returns the oil to the external sump.
17 The conditions that the engine runs at are as follows:
18 Condition Speed Load Temperature (C) l9 (rpm) (in kg.) Coolant Oil l (idle)a 800 182 80 98 21 2 (48 kph)b1200 205 ~0 98 22 ~ (48 kph)a1200 409 80 98 23 4 (88 kph)h2200 409 80 98 24 a - engine load higher than road load.
b - engine load equivalent to road load.
26 The results are expressed as a percentage fuel e-27 conomy credit with respect to the referenced oil, as are all 28 fuel economy credit results reported in the Examples. ~esults ~9 at the 0.2 wt. ~ treat level for ~oth GMO and the GMO/GDO mixture are set fc rth in Table I.

5~S~
g 2 Fue 1 Economy Credi t, 96 3 Engine Condition GMO GMO/GD0 4 1 4.Q 2.6 2 2.5 3.0

6 3. 1.5 1.8

7 4 0.9 0.5

8 Weighted Average 1.9 1.8 g EXAMPLE 2 ~o (a) Compara~ive evaluations utilizing increased a-11 mounts of the GMO/GDO mixture, that is, at the 0.3 weight 12 percent and 0.5 weight percent levels showed no increase in fuel 13 economy credit for treatment at these levels and in some cases, 14 an adverse effect on fuel economy credits or other lubricating oil performance criteria, such as increas2d piston deposit 16 formation tendencies or poor results in bearing corrosion 17 tests.
18 (b) Coeffirient of friction (CF) testing using a 19 Roxana Four-ball wear tester in acordance with the procedure described in ASTM D2266-67 at 110C, 2.5 RPM at both 15 kg and 21 3 kg was carried out with a formulated mineral oil (Base oil) 22 containing conventional amounts of dispersant (2.12 %)~ basic 23 metal sulfonate (1.02~), antioxidant (0.72%), anti-wear ad-24 ditive (1.96%) and viscosity index improver (only present at 8.7 wt. ~ in test oils 5 and 6 to evaluate compatibility) to 26 which was added varying amounts of the GDO/GMO mixture. The 27 results in Table II below show essentially no additional 28 friction reducing benefit at levels in excess of 0.2 wt. % and, 29 at 0.9 wt. ~ in the test, potential instability or incompa-tibility was observed since the samples appeared hazy.

~os~s~

1 TABLE II_- CF RESULTS
2 Test Oil CF (15 kg) CF (3 kg) Compatibility 3 1. Base Oil 0~3 0.19 Clear 4 2. Base Oil + C.18 C;.14 Clear 0.1% GDO/GMO
6 3. Base Oil + 0.11 0.11 Clear 7 0.2% GDO/GMO
8 4. Base Oil ~ 0.11 0.11 Clear

9 0.3% GDO/GMO

10 5.* Base Oil + 0.11 0.11 Clear

11 0.4~ GDO/GMO

12 6.* Base Oil + 0.10 0.10 Hazy

13 0.9% GDO/GMO

14 * 8.7 wt. % of a V.I. improver was present only in formula-tions 5 and 6 since compatibility was important at these 16 concentrations.

18 (a) The Laboratory Fuel Economy Test of Example 1 was 19 repeated utilizing a 10W40 multigrade mineral oil containing 0.09 wt. ~ of the GMO/GDO mixture as the fuel economy additive.
21 The oil contained about 14~ by wt. of a multifunctional disper~
22 sant viscosity index improver (acryloid 1155), 0.5% disper-23 sant, 1.85% of basic metal detergent, 0.75 wt.% of anti-wear 24 additive and 0.75% antioxidant.
Table III shows the fuel economy credits over the oil 26 used as the reference in Example 1.

28Engine Condition Fuel Economy Credit, %
29 1 5.9 30 2 0.5 31 3 0.9 32 4 1.1 33Weighted Average 1.8 34 (b) Utilizing the same oil as Example 3(a) the ~2~S~L

1 Laboratory Fuel Economy results were confirmed in the Proposed 2 ASTM S Car Interim Fuel Economy Procedure which utilized the EPA
3 car certification cycle in 5 automobiles having engine sizes of 4 2.3 liter, 2.8 liter, 3.7 liter, 3.8 liter and 5.0 liter. Five 5 Car average fuel economy credit of 1.64% was obtained in one 6 series of fuel economy tests.
7 Based upon these results one would expect that the 8 fuel economy credits attributed to a glycerol mono-oleate to be g non-cumulative when the treatment level is increased above the 10 range of about 0.1 wt. % to 0.2 wt. % and the inventors hereof 11 have found this principle is generally true in fuel economy ad-12 ditives technology, i.e., increasing the amount of friction 13 modifier additive does not result in a concomitant straight 14 line proportional increase in the observed fuel economy. For

15 example, combining the glycerol oleate mixed esters described

16 above with a known fuel economy additive such as a dimerized

17 linoleic acid ester as described in U.S. Patent 4,105,571 has

18 been found to offex no better fuel economy than when either

19 compound is used alone. This will be demonstrated in Example

20 6. Thus~ as a general rule increasing the treat level of the

21 friction modifier itself or increasing the treat level by

22 adding another friction modifier known to have fuel economy

23 benefits has not heretofore been found to offer a fuel economy

24 improvemant. Examples 1-4 and 6 are presented here to il-

25 lustrate these principles.

26 EXAMPLE 4

27 Evaluation of Copper Compounds for Fuel Economy

28 The LEFET test was carried out using an Oil* equiva-

29 lent to the ~R straight grade oil of Example 1 except that 0.3

30 wt. ~ of a 40 wt% solution of copper oleate in mineral oil, which

31 is equivalent to 120 ppm copper was used in place of the anti-

32 oxidant reported in Example 1. The LEFET results for this test

33 are below in Table IV:

~2~
~12-2 Engine Condition Fuel Economy Credit 3 1 4.9 4 2 2.5 3 1.5 6 4 0.0 7 Weighted Average l.9 %
8 * Oil contained 2.7 wt. ~ dispersant, l.0 w~. %
9 overbased metal detergent additlve, 1.4 wt. ~
antiwear additive and 120 ppm copper as copper 11 oleate formulated to a straight grade 20W30.
12 This example establishes that copper does provide a significant 13 fuel economy credit in addition to i~s antioxidant effective-14 ness The foregoing examples, carried out in fired engine 16 tests using a 5.0 liter 8-cylinder engine demonstrate that the 17 oil-soluble organic coppPr compounds offer a beneficial fuel 18 economy credit and that the glycerol ester offers a fuel economy 19 credit which does not increase to any significant degree above 20 the 0.2 wt. % treat level.
21 EXAMPLE 5 - Evaluation of Combination of Copper 22 Compound and Glycerol Ester 23 To determine if oils containing both the oil-2~ soluble organic copper compound and glycerol ester friction 25 modifier would exhibit any complementary effect, different 26 oils were formulated and tested in Ford 2.3 liter 4-cylinder 27 engine. The purpose of these tests was to evaluate the increase 28 in fuel economy credits when the copper compound and the 29 glycerol ester were combined over the credits obtained with 30 these additives separately in the same engine. Fuel economy 31 credit values will vary among engines of differing sizes. This 3~ is due to the inherent differences in engine design and oper-33 ating conditions. It is known therefore that the values for a

34 2.3 liter 4-cylinder engine will be lower than fuel economy

35 credit values for a 5 liter 8-cylinder used in these examples.

36 The additive content in weight percent of the oils

37 evaluated is given below, balance is basestock mineral oil.

~s~

1 Oil _ Oil B o i 1 c Oil D Oil E Oil 2 Dispersant 5.5 5.5 5.5 5.5 5 5 5 5 3 Anti-Wear 1~0 1.0 1.0 1.0 1.0 1.0 4 overbased Metal 1.4 1.4 1.4 1.4 1.4 1.4 5 Detergent 6 GMD/GDO* ~ - _ 0.2 _ 0.2 7 Cupric oleate ~ - 0.118 0.118 0.118 8 Cupric Stearate - 0.065 g * Same as Example 1 Fuel economy results for these oils are given in 11 Table V below. Percentage credits are calculated again with 12 respect to the same reference oil used in Example 1.

13 T BLE V_ % F.E. Credit, 14 EngineEngine Weighted 15 O_ Condition 1Condition 4 Average 16 A - 0.25 0.07 0.08 17 B 0.90 0.40 0.63 1~ C 1.4 0.20 0.50 19 D 2.1 0.40 0.90 E 1.0 -0.42 C~.20 21 F 1.1 0.13 0.20 22 Oil D represents the advantage of this invention.
23 Oils B, C, E show the maximum values one can expect to 24 obtain based on the credits due only to the copper compound.
25 Oil D, however, achieves a value of 0.9%. This result is not ~6 expected because it is known, as a general principlet that 27 merely increasing the treatment level of a given fuel economy 28 additive does not increase the credit obtained.
2~ EXAMPLE 6 To demonstrate the principle that fuel economy ad-31 ditives, when combined together, cannot be expected to have 32 a combined effect. The following oils G, H, I and J were 33 evaluated for fuel economy in the 5.0 L engine using the same 34 LEFET procedure of Example I. Oil G WdS a formulated lubricating 54~i;3L

1 oil having 4 wt~ dispersant, 1 wt% overbased metal sulfonate, 2 1.5 wt% antioxidant and 2 wt~ anti-weax additive. oil H was the 3 same as Oil G, except for the inclusion of 0.1 wt% dimerized 4 linoleic acid ester of diethylene glycol as disclosed in U.S.
5 Patent 4,105,571. Oil I was the same as Oil G exceplt: 0~2 wt%
6 of the GMO/GDO ester was added. Oil J was the same as Oil G
7 except both 0.1 wt% of the dimerized linoleic acid ester and 0.2 8 wt% of the GMO/GDO were added. Fuel economy results for these 9 four oils are shown below in Table VI.
TABLE VI
11 % Fuel Economy credit, Weighted 12 Oil Average 13 G 1.2%
14 H 2.4%
I 2.2%
16 J 2.4%

18The positive effect on fuel economy attributable 19 to use of the two component fuel economy additive of this 20 invention is further demonstrated by LEFET results in the 5.0 21 L engine and th~se data confirm the results shown above in 22 Example 5. Here Oil K contained 5.5 wt% dispersant, 1 wt%
23 overbased metal sulfonate, 1.4 wt% anti-wear additive and 1 wt~
24 anti-oxidant. Oil L was the same as Oil K with 0.3 wt% of a 40 25 wt% solution of copper oleate (120 ppm copper) included and Oil 26 M was the same as oil L except 0.1 wt% of the GMO/GDO glycerol 27 oleate was included. Fuel economy credits are in Table VII
28 below.

Oil% Fuel Economy Credit, Wei~hted Average 31 K - 0.1 32 L 1.4~
33 M 2.2%

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE
IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A lubricating oil composition comprising a major amount of an oil of a lubricating viscosity which has incorporated therein (a) from about 0.05 to about 0.20 weight percent of a glycerol partial ester or mixtures thereof of a C16-C18 fatty acid, and (b) about 5 to 500 ppm of copper in the form of an oil-soluble organic copper compound, said (a) and (b) components exhibiting a combined effect improving the fuel economy of an internal combustion engine.

2. The composition of claim 1 wherein the fatty acid is oleic acid.

3. The composition of claim 1 wherein said partial ester is a mixture of glycerol monooleate and glycerol dioleate.

4. The composition of claims 1-3 wherein there is present 0.1 to 0.2 weight percent of said partial ester.

5. A lubricating oil composition comprising a major amount of an oil of a lubricating viscosity which has incorporated therein (a) from about 0.05 to about 0.20 weight percent of a glycerol partial ester or mixtures thereof of a C16-C18 fatty acid, and (b) about 5 to 500 ppm of copper in the form of an oil-soluble organic copper compound, said (a) and (b) components exhibiting a combined effect improving the fuel economy of an internal combustion engine, and wherein said lubricating oil composition further comprises an ashless dispersant, a metal detergent additive and a zinc dihydrocarbyl dithiophosphate anti-wear additive in conventional amounts to provide their normal attendant functions.

6. The composition of claim 5 wherein said lubricating oil composition contains a viscosity index improver.

7. The composition of claims 5 or 6 where said copper compound is copper oleate.

8. The composition of claims 5 or 6 where there is present 60 to 200 ppm of copper.

9. A method of improving the fuel economy of an internal combustion engine by lubricating the internal portion thereof with a lubricating oil composition containing (a) 0.05 to 0.2 wt % of a glycerol partial ester of a C16-C18 fatty acid or mixtures thereof and (b) about 5 to 500 ppm of copper in the form of an oil-soluble organic copper compound, said (a) and (b) components exhibiting a combined effect in improving the fuel economy of said engine.

10. The method of claim 9 wherein said (a) component is a mixture of glycerol monooleate and glycerol dioleate present in an amount of from 0.1 to 0.2 wt %, and said (b) component is copper oleate present in an amount to provide 60 to 200 ppm copper.