Ester-based lubricant to reduce oil consumption in a thermal engine

Abstract

Ester-based lubricant for reducing the oil consumption of a heat engine The present invention relates to the use of at least one ester in a lubricating composition dedicated to a heat engine, in particular in a vehicle, for reducing the oil consumption of the engine, said ester(s) being formed between a monoalcohol or polyalcohol, saturated or unsaturated, linear or branched, C1 to C16, and one or more monocarboxylic acids, saturated, linear or branched, C6 to C20. Figure for the abstract: none

Description

Title of the invention: Ester-based lubricant for reducing the oil consumption of a thermal engine

[0001] The present invention relates to the field of lubricating compositions, more particularly the field of lubricating compositions for thermal engines or combustion engines, in particular in vehicles, for example for heavy goods vehicles. It relates more particularly to the use of esters in lubricating formulations dedicated to thermal engines, to lower the oil consumption of the engine.

[0002] Lubricating compositions, also called "lubricants", are commonly used in the various components of motor vehicles for the main purpose of reducing the friction forces between the various moving metal parts in these components, in particular in the engine. They are also effective in preventing premature wear or even damage to these parts, and in particular to their surface. To do this, lubricating compositions intended for internal combustion engines are conventionally composed of one or more base oils, in particular mineral base oils, with which are associated several additives dedicated to stimulating the lubricating performance of the base oil, for example friction modifying additives, but also to providing additional performance.

[0003] Current environmental concerns, particularly with a view to reducing carbon dioxide emissions, induce an urgent need to reduce the fuel consumption of motor vehicles. As such, lubricating compositions can represent an effective means of acting on fuel consumption or "Fuel Eco" (FE) properties (for "fuel economy" in English terminology), via their impact on the friction forces generated between the different components of motor vehicles. The more or less fluid grade of the base oil thus makes it possible to impact the Fuel Eco properties of the lubricant. In particular, it is known that the reduction in viscosity of the base oils used in lubricants favorably impacts the Fuel Eco properties ([1], [2], [3]).

[0004] However, base oils conventionally used in lubricants for internal combustion engines, in particular base oils of group I, II and / or III of the API classification, generally exhibit increased volatility as their viscosities decrease. However, the volatility of base oils, which can be characterized by the standardized CEC L-040-093 Noack volatility test, is included in international specifications for lubricant classifications such as API, ILSAC or ACEA. It is thus present in most car manufacturers' specifications, in order to guarantee the durability performance of their engine. In fact, volatility is generally linked to the engine's oil consumption ([4], [5]). This oil consumption over time must necessarily be controlled in order to have a sufficient oil level and thus limit the need to top up oil between two oil change intervals.

[0005] Therefore, controlling engine oil consumption generally involves using Noack low volatility lubricating oil, to the detriment of improving Fuel Eco performance.

[0006] Thus, reducing engine oil consumption, while maintaining or even improving the Fuel Eco properties of lubricants for combustion engines, remains a challenge.

[0007] The present invention aims precisely to propose the formulation of lubricants making it possible to achieve a reduction in oil consumption, while preserving good properties in terms of reducing fuel consumption or Fuel Eco properties.

[0008] To this end, the present invention relates, according to a first of its aspects, to the use of at least one ester in a lubricating composition dedicated to a thermal engine, in particular in a vehicle, to reduce the oil consumption of the engine, said ester(s) being formed between a monoalcohol or polyalcohol, saturated or unsaturated, linear or branched, C1 to C16, and one or more monocarboxylic acids, saturated, linear or branched, C6 to C20.

[0009] In the remainder of the text, and unless otherwise indicated, the term "ester according to the invention" will be used to refer to a monoester or polyester meeting the aforementioned definition. The formulation of a lubricant according to the invention may comprise the use of a single ester according to the invention or a mixture of at least two distinct esters according to the invention. Examples of esters according to the invention are detailed in the remainder of the text.

[0010] In particular, an ester used according to the invention may be chosen from monoesters and diesters formed between a monoalcohol or a dialcohol, saturated or unsaturated, preferably saturated, linear or branched, C1 to C12, in particular C2 to C10, and one or more monocarboxylic acids, saturated, linear or branched, in particular linear, C8 to C16.

[0011] As is apparent from the examples which follow, the inventors have found that the use of an ester or mixture of esters according to the invention in a lubricating composition for a combustion engine advantageously makes it possible to reduce oil consumption.

[0012] Surprisingly, this reduction in oil consumption associated with the implementation of one or more ester(s) according to the invention is not correlated with the characterization of Noack volatility.

[0013] In fact, as illustrated in the examples which follow, with Noack iso-volatility, the use of esters according to the invention makes it possible to achieve improved oil consumption levels compared to the use of conventional base oils of group I, II and / or III, in particular group II or III. In other words, the use of a lubricating composition based on one or more esters according to the invention makes it possible to lower the oil consumption of the engine, compared to a lubricating composition, of similar Noack volatility, based on conventional base oil(s) of group I, II and / or III, in particular group II or III, and not comprising an ester according to the invention.

[0014] The Noack volatility is more particularly determined according to the CEC L-40-A-93 standard, the Noack volatility value indicated according to this standard corresponding to the mass fraction (% by mass) lost after heating in a constant air flow at 250°C for 60 minutes. By "similar Noack volatility" is meant that the relative variation between the respective Noack volatilities of the two lubricants compared is less than 20%, in particular less than 15%. The relative variation of the Noack volatility (noted NV) between a CL lubricant and a comparative lubricant is given by the quotient of the difference between the two volatilities NVcl and NVcc by NV cc ((NVcl - NVcc) / NVcc).

[0015] As detailed in the examples, the engine oil consumption performance can be evaluated by determining the lubricating oil consumption, for different engine operating points, using radioactive tracers incorporated in the lubricating oil, and the amount of radioactive residues of which, measured in the exhaust gases, is directly related to the engine oil consumption. The evaluation of the oil consumption representative of an engine cycle (in g / h eq. WHTC) can be carried out using a mapping of engine operating points, for a dynamic cycle "WHTC" ("Word Harmonized Transient test Cycle"), as explained in more detail in the examples which follow.

[0016] In particular, the use of a lubricant based on ester(s) according to the invention makes it possible to achieve a reduction in oil consumption, estimated on the basis of a WHTC engine cycle, of at least 20%, in particular at least 35%, compared to the engine oil consumption obtained by using a lubricating composition free of ester as defined above, in particular based on conventional base oils of group I, II and / or III, for example base oils of group II or III, and having a Noack volatility, measured according to the CEC L-040-093 standard, equivalent to plus or minus 15% relative variation.

[0017] Advantageously, the reduction in oil consumption makes it possible to limit oil top-ups and / or to extend the oil change interval.

[0018] The present invention also relates to the aforementioned use for extending the oil change interval.

[0019] The present invention also relates to the aforementioned use for reducing engine oil consumption while maintaining good engine fuel economy properties or Fuel Eco properties.

[0020] As mentioned above, the improvement in terms of reduction of oil consumption linked to the implementation of a lubricant based on ester(s) according to the invention is advantageously not associated with Noack volatility or an increase in viscosity of the lubricant.

[0021] Thus, advantageously, the improvement in oil consumption levels through the use of esters in a lubricant formulation according to the invention is not to the detriment of the Fuel Eco properties of the lubricant. Advantageously, the use of esters in an engine lubricant according to the invention makes it possible to obtain a lubricant combining both good properties in terms of reducing oil consumption and Fuel Eco performance.

[0022] Also, it is possible, for the same level of performance in terms of oil consumption, to formulate lubricating compositions based on esters having higher Noack volatilities and lower viscosities, in order to achieve increased Fuel Eco performance, without impacting the oil consumption properties.

[0023] The invention also relates to the use of a lubricating composition based on one or more esters formed between a monoalcohol or polyalcohol, saturated or unsaturated, linear or branched, C1 to C16, and one or more monocarboxylic acids, saturated, linear or branched, C6 to C20, to reduce the oil consumption of a thermal engine lubricated by means of said lubricating composition, in particular in a vehicle.

[0024] Advantageously, a lubricating composition implemented according to the invention, comprising one or more esters according to the invention as defined previously, advantageously combines good properties in terms of oil consumption and good “Fuel Eco” properties.

[0025] The invention also relates to the use of a lubricating composition according to the invention dedicated to an engine, in particular to a vehicle engine, to reduce the oil consumption of the engine, without impacting the fuel economy or Fuel Eco properties.

[0026] It also describes a process or method for reducing the oil consumption of a heat engine, in which said engine is lubricated by means of a com lubricating position based on one or more esters according to the invention, as defined above.

[0027] Furthermore, the use of esters according to the invention, by acting on the reduction of oil consumption, advantageously makes it possible to reduce the carbon footprint, in particular at the level of the lubricant usage phase.

[0028] The invention therefore also relates to the use of a lubricating composition according to the invention for reducing the carbon footprint by reducing oil consumption, in particular compared to a lubricating composition formulated solely from one or more base oils distinct from the esters according to the invention, in particular group II and / or III base oil(s).

[0029] Furthermore, the use of esters according to the invention, by acting on the reduction of oil consumption, advantageously makes it possible to reduce polluting emissions linked to lubricants, in particular at the level of the lubricant usage phase. The use therefore makes it possible to protect exhaust gas post-treatment systems and to extend their service life or to improve their efficiency.

[0030] The invention therefore also relates to the use of a lubricating composition according to the invention for increasing the durability of post-treatment systems and reducing pollutant emissions, in particular compared to a lubricating composition formulated solely from one or more base oils distinct from the esters according to the invention, in particular group II and / or III base oil(s).

[0031] Other characteristics and variants of the use of a lubricant based on ester(s) according to the invention to reduce engine oil consumption will become more apparent on reading the description and examples which follow, given by way of illustration and not limitation of the invention.

[0032] In the rest of the text, the expressions “between ... and ...”, “ranging ... to ...” and “varying from ... to ...” are equivalent and are intended to mean that the limits are included, unless otherwise stated.

[0033] Unless otherwise indicated, the expression “comprising a(n)” must be understood as “comprising at least one(n)”. Ester-based lubricating composition

[0034] As indicated above, a lubricating composition formulated according to the invention comprises at least one ester formed between a monoalcohol or polyalcohol, saturated or unsaturated, linear or branched, C1 to C16, and one or more monocarboxylic acids, saturated, linear or branched, C6 to C20.

[0035] It is understood that, within the framework of the present invention, the lubricating composition formulated according to the invention may use a single ester according to the invention, as defined above, or a mixture of at least two esters according to the invention, as defined previously.

[0036] In the context of the invention, the term “Ct-Cz” where t and z are integers, means a carbon chain which can have from t to z carbon atoms; for example C1-C4 a carbon chain which can have from 1 to 4 carbon atoms;

[0037] The alcohol from which the ester used according to the invention is formed is a monoalcohol, saturated or unsaturated, linear or branched, comprising from 1 to 16 carbon atoms, preferably from 1 to 12 carbon atoms, or a polyalcohol, preferably dialcohol (or diol), linear or branched, comprising from 1 to 16 carbon atoms, preferably from 1 to 12 carbon atoms.

[0038] By “monoalcohol” is meant a compound formed from a hydrocarbon chain of alkyl or alkenyl type, carrying a hydroxyl function.

[0039] By “polyalcohol” or “polyol” is meant a compound formed from a hydrocarbon chain of alkyl or alkenyl type, carrying at least two hydroxyl functions.

[0040] By “alkyl” is meant a saturated, linear or branched aliphatic group; for example, a C1-C4-alkyl group represents a carbon chain of 1 to 4 carbon atoms, linear or branched, more particularly a methyl, ethyl, propyl, isopropyl, butyl, isobutyl or tert-butyl.

[0041] By “diacohol” or “diol” is meant a compound formed from a hydrocarbon chain of alkyl or alkenyl type, carrying two hydroxyl functions.

[0042] Preferably, the polyol used according to the invention comprises 2 to 5 hydroxyl groups, preferably comprises 2 to 3 hydroxyl groups and even more preferably comprises 2 hydroxyl groups. Preferably, the polyol used according to the invention is therefore a di-alcohol or diol.

[0043] An alcohol whose alkyl or alkenyl chain is linear, as opposed to a branched chain, is described as “linear”.

[0044] An alcohol whose hydrocarbon chain is a saturated chain of alkyl type, as opposed to an unsaturated chain of alkenyl type, is described as “saturated”.

[0045] Such alcohols may be commercially available or prepared according to synthetic methods known to those skilled in the art.

[0046] According to one embodiment, the alcohol from which the ester used according to the invention is formed is a monoalcohol, saturated or unsaturated, preferably saturated, linear or branched, in C1 to C12, in particular in C2 to C10.

[0047] According to one embodiment, the alcohol from which the ester used according to the invention is formed is a diol, saturated or unsaturated, preferably saturated, linear or branched, in C1 to C12, in particular in C2 to C10.

[0048] According to one embodiment, the alcohol from which the ester used according to the invention is formed is a branched, saturated or unsaturated, preferably saturated, C4 to C16, in particular C6 to C12, monoalcohol.

[0049] According to one embodiment, the alcohol from which the ester used according to the invention is formed is a diol, linear or branched, saturated or unsaturated, preferably saturated, in C1 to C6, in particular in C1 to C4.

[0050] According to one embodiment, the alcohol from which the ester used according to the invention is formed is a saturated and branched monoalcohol, C5 to C10, for example 2-ethylhexanol.

[0051] According to one embodiment, the alcohol from which the ester used according to the invention is formed is a diol, saturated, branched or linear, C2 to C5, for example propylene glycol.

[0052] The acid from which the ester used according to the invention is formed is chosen from saturated, linear or branched, C6 to C20 monocarboxylic acids.

[0053] By "monocarboxylic acid" is meant according to the invention a compound formed from a hydrocarbon chain of alkyl or alkenyl type carrying at one of its ends a carboxylic acid function.

[0054] A monocarboxylic acid whose alkyl or alkenyl chain is linear, as opposed to a branched chain, is described as “linear”.

[0055] A carboxylic acid whose hydrocarbon chain is a saturated chain of alkyl type, as opposed to an unsaturated chain of alkenyl type, is described as “saturated”.

[0056] Such acids may be commercially available or prepared according to synthetic methods known to those skilled in the art.

[0057] According to one embodiment, the carboxylic acids from which esters used according to the invention are formed may in particular be monocarboxylic acids, saturated, linear or branched, in particular linear, with C8 to C16, in particular with C8 to C14 carbon atoms, preferably with C9 to C13, such as for example nonanoic acid, dodecanoic acid, etc.

[0058] According to one embodiment, the ester used according to the invention is obtained from one or more monocarboxylic acid(s) as defined above.

[0059] Preferably, the ester used according to the invention is a diester obtained from two monocarboxylic acids comprising 8 to 14 carbon atoms.

[0060] According to one embodiment, the ester used according to the invention is chosen from monoesters and diesters formed between a monoalcohol or a dialcohol, saturated or unsaturated, preferably saturated, linear or branched, in C1 to C12, in particular in C2 to C10, and one or more monocarboxylic acids, saturated, linear or branched, in particular linear, in C8 to C16.

[0061] According to one embodiment, the ester used according to the invention is chosen from:

[0062] (i) monoesters formed between a branched, saturated or unsaturated monoalcohol, of preferably saturated, C4 to C16, in particular C6 to C12, and a saturated, linear or branched, preferably linear, C6 to C20 monocarboxylic acid, in particular in C8 to C16;

[0063] (ii) diesters formed between a linear or branched, saturated or unsaturated, preferably saturated, C1 to C6, in particular C1 to C4, dialcohol and one or more saturated, linear or branched, preferably linear, C6 to C20, in particular C8 to C16, monocarboxylic acids;

[0064] and mixtures thereof.

[0065] According to one embodiment, the ester used according to the invention, alone or as a mixture, is chosen from:

[0066] (i) the monoesters of the following formula (I):

[0067] R“-C(O)-O-CH2-CH(R2)-R1 (I)

[0068] in which:

[0069] - Ra represents a saturated, linear or branched hydrocarbon group, of preferably linear, comprising from 7 to 15 carbon atoms, preferably from 8 to 12 carbon atoms; and

[0070] - R1 and R2 represent, independently of one another, a hy group carbon, linear or branched, saturated or unsaturated, preferably saturated, from Cl to C5; or a hydrogen atom;

[0071] (ii) the diesters of the following formula (II):

[0072] Rb-C(O)-O-([C(R3)2]nO)sC(O)-Rc (II)

[0073] in which:

[0074] - Rb and Rc, identical or different, represent hydrocarbon groups, saturated, linear or branched, preferably linear, comprising from 7 to 15 carbon atoms, preferably from 8 to 12 carbon atoms;

[0075] - R3 represent, independently of each other, a hydrogen atom or a (Ci-C5)alkyl group, linear or branched, in particular a methyl, ethyl or propyl group, in particular methyl;

[0076] - s is 1 or 2; preferably s is 1;

[0077] - n is 1, 2 or 3; it being understood that, when s is different from 1, n can be identical or different;

[0078] and mixtures thereof.

[0079] According to one embodiment, the ester used according to the invention, alone or as a mixture, is chosen from monoesters and diesters formed from a saturated and branched monoalcohol, C5 to C10, for example 2-ethylhexanol, or a saturated, branched or linear dialcohol, C2 to C5, for example propylene glycol, and one or more saturated and linear monocarboxylic acids, C8 to C14, in particular C9 to C12.

[0080] In one embodiment, the ester used according to the invention is chosen from the monoesters as defined above.

[0081] According to one embodiment, the ester used according to the invention is chosen from the mo noesters formed between a monoalcohol and a monocarboxylic acid, saturated, linear or branched, in particular linear, C8 to Cl6.

[0082] According to one embodiment, the ester used according to the invention is a monoester formed between a branched, saturated or unsaturated, preferably saturated, C4 to C16, in particular C6 to C12, monoalcohol and a saturated, linear or branched, preferably linear, C6 to C20, in particular C8 to C16, monocarboxylic acid.

[0083] Advantageously, the ester used according to the invention is a monoester of formula (I) as defined above.

[0084] According to one embodiment, in formula (I), Ra represents a saturated group. According to one embodiment, in formula (I), Ra represents a linear group.

[0085] Preferably, in formula (I), Ra represents a linear, saturated hydrocarbon group comprising from 7 to 15 carbon atoms. In particular, in formula (I), Ra represents a linear, saturated hydrocarbon group comprising from 8 to 12 carbon atoms.

[0086] According to one embodiment, in formula (I), Ra is chosen from saturated linear hydrocarbon groups comprising from 7 to 13 carbon atoms, preferably comprising from 8 to 12 carbon atoms. Preferably, Ra represents an n-octyl, n-nonyl, n-decyl or n-undecyl group.

[0087] According to one embodiment, in formula (I), R1 and / or R2 represent, independently of one another, a hydrogen atom.

[0088] According to one embodiment, in formula (I), R1 represents a hydrogen atom and R2 represents a linear or branched, saturated hydrocarbon group comprising from 1 to 5 carbon atoms.

[0089] According to one embodiment, in formula (I), R1 represents a linear or branched, saturated hydrocarbon group comprising from 1 to 5 carbon atoms and R2 represents a hydrogen atom.

[0090] Preferably, in formula (I), R1 and R2 represent, independently of one another, a linear or branched, saturated hydrocarbon group comprising from 1 to 5 carbon atoms.

[0091] According to one embodiment, in formula (I), R1 is a linear and saturated hydrocarbon group comprising from 1 to 5 carbon atoms. Preferably, R1 is chosen from ethyl, propyl or butyl groups.

[0092] According to one embodiment, in formula (I), R2 is a linear and saturated hydrocarbon group comprising from 1 to 5 carbon atoms. Preferably, R2 is chosen from ethyl, propyl or butyl groups.

[0093] According to one embodiment, the ester used according to the invention, alone or as a mixture, is chosen from monoesters formed from a saturated and branched monoalcohol, in C5 to CIO, for example 2-ethylhexanol, and a saturated, linear monocarboxylic acid, C8 to C14, in particular C9 to C12, for example lauric acid.

[0094] According to one embodiment, the ester used according to the invention is chosen from the diesters as defined above.

[0095] According to one embodiment, the ester used according to the invention is chosen from diesters formed between a monoalcohol or a dialcohol, saturated or unsaturated, preferably saturated, linear or branched, in C1 to C12, in particular in C2 to C10, and one or more monocarboxylic acids, saturated, linear or branched, in particular linear, in C8 to C16.

[0096] According to one embodiment, the ester used according to the invention is chosen from diesters formed between a linear or branched, saturated or unsaturated, preferably saturated, C1 to C6, in particular C1 to C4, dialcohol and one or more saturated, linear or branched, preferably linear, C6 to C20, in particular C8 to C16, monocarboxylic acids.

[0097] According to one embodiment, the ester used according to the invention, alone or as a mixture, is chosen from the diesters of formula (II) as defined above.

[0098] Preferably, in formula (II), Rb and Rc, identical or different, represent saturated and linear hydrocarbon groups, comprising from 7 to 15 carbon atoms, preferably from 8 to 12 carbon atoms.

[0099] Preferably, in formula (II), Rb and Rc are different.

[0100] Preferably, in formula (II), R3 represent, independently of each other, others, a hydrogen atom or a linear (Ci-C5)alkyl group, in particular a methyl, ethyl or propyl group, in particular methyl.

[0101] Preferably, in the above-mentioned formula (II), s is equal to 1.

[0102] Preferably, in the above-mentioned formula (II), n is 2.

[0103] According to one embodiment, the ester used according to the invention, alone or as a mixture, is chosen from the diesters of formula (III):

[0104] Rb-C(O)-O-(CH(R4)-CH2-O)-C(O)-Rc (III)

[0105] in which:

[0106] - Rb and Rc are as defined in formula (II), and are preferably different, and

[0107] - R4 is a (Ci-C5)alkyl group, linear or branched, in particular a group methyl, ethyl or propyl, especially methyl.

[0108] Preferably, in formula (III), Rb and Rc are different and are hydrocarbon groups, saturated or unsaturated, linear or branched, comprising from 7 to 13 carbon atoms, preferably from 9 to 11 carbon atoms.

[0109] According to one embodiment, the ester used according to the invention, alone or as a mixture, is chosen from monoesters and diesters formed from a saturated and branched monoalcohol, C5 to C10, for example 2-ethylhexanol, or a saturated, branched or linear, C2 to C5, for example propylene glycol, and one or more monocarboxylic acids, saturated and linear, C8 to C14, in particular C9 to C12.

[0110] According to one embodiment, the lubricating composition used according to the invention comprises a single ester as defined above, in particular a diester as defined above, and more particularly a diester of formula (II), in particular of formula (III) mentioned above.

[0111] According to one embodiment, the lubricating composition used according to the invention comprises a single diester of formula (II) mentioned above, in particular of formula (III).

[0112] According to one embodiment, the lubricating composition used according to the invention comprises a mixture of at least one monoester, in particular of formula (I), and at least one diester, in particular of formula (II), in particular of formula (III).

[0113] According to one embodiment, the lubricating composition used according to the invention comprises a mixture of at least one monoester, in particular of formula (I), and at least one diester, in particular of formula (II) and more particularly of formula (III), preferably in a diester(s) / monoester(s) mass ratio strictly greater than 1, in particular between 1.1 and 1.5.

[0114] According to one embodiment, the lubricating composition used according to the invention comprises a mixture of at least one monoester, in particular of formula (I), and at least one diester, in particular of formula (II) and more particularly of formula (III), in a diester(s) / monoester(s) mass ratio strictly greater than 1, in particular between 1.1 and 1.5.

[0115] Preferably, said ester according to the invention or mixture of esters according to the invention, in particular as described above, is used in an amount of at least 15% by mass, in particular from 20% to 80% by mass, in particular from 30% to 70% by mass, relative to the total mass of the lubricating composition. Other components of the lubricating composition

[0116] A lubricating composition according to the invention may comprise, in addition to one or more esters as defined above, one or more base oils, distinct from said esters according to the invention, in particular one or more base oils of group II and / or III, as well as additives, in particular as defined in the remainder of the text.

[0117] These base oils can be chosen from base oils conventionally used in the field of lubricating oils, such as mineral, synthetic or natural, animal or vegetable oils or their mixtures.

[0118] The base oils used in the lubricating compositions according to the invention may in particular be oils of mineral or synthetic origin belonging to groups I to V according to the classes defined in the API classification, or their equivalents according to the ATIEL classification (table 1), or their mixtures.

[0119] [Tables 1] Saturates content Sulphur content Viscosity index (VI) Group I Mineral oils <90% > 0.03% 80 <VI < 120 Groupement II Huiles hydrocraquées >90% <0.03% 80 <VI < 120 Groupement III Huiles hydrocraquées ou hydro-isomérisées >90% <0.03% >120 Group IV Polyalphaolefins (PAO) Group V Esters and other bases not included in groups I to IV

[0120] Mineral base oils include all types of base oils obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, de-alphatting, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing.

[0121] Mixtures of synthetic and mineral oils, which can be bio-sourced, can also be used.

[0122] In particular, a lubricating composition formulated according to the invention based on one or more esters as described above, may further comprise one or more base oils chosen from group I, II, III and IV oils of the API classification. In particular, a lubricating composition formulated according to the invention may comprise one or more group II and / or III base oils, in particular at least one group III base oil.

[0123] According to a particular embodiment, a lubricating composition formulated according to the invention based on one or more esters as described above, may comprise at least 10% by mass, in particular from 15% to 75% by mass and more particularly from 20% to 60% by mass, of one or more base oils distinct from said ester(s), in particular chosen from group II and / or III oils, in particular group III, relative to the total mass of said lubricating composition.

[0124] Preferably, the group III base oil or oils represent(s) at most 85%, in particular at most 70%, in particular at most 50% and more particularly at most 30% by weight, of the total weight of the base oils of the lubricating composition.

[0125] Preferably, the base oil or mixture of base oils of a lubricating composition formulated according to the invention has a kinematic viscosity measured at 100°C according to ASTM D445 ranging from 2.5 to 8 mm2 / s, in particular from 2.5 to 6 mm2 / s, relative to the total mass of said lubricating composition.

[0126] In a particular embodiment, said ester(s) according to the invention and said base oil(s) distinct from said ester(s), in particular said group II and / or III base oil(s), are used in an ester(s) / additional base oil(s) mass ratio of between 16 and 77, in particular between 50 and 68.

[0127] A lubricating composition implemented according to the invention may further comprise all types of additives suitable for use in an engine lubricant, in particular for a vehicle engine.

[0128] These additives can be introduced in isolation and / or in the form of a mixture like those already available for sale for formulations of commercial lubricants for vehicle engines, with performance levels as defined by the ACEA (Association of European Automobile Manufacturers) and / or the API (American Petroleum Institute), well known to those skilled in the art.

[0129] Such additives may be selected from one or more selected from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index improvers, pour point depressant additives, dispersants, thickeners, corrosion inhibitors, copper passivating agents, and mixtures thereof.

[0130] Anti-wear additives and extreme pressure additives protect friction surfaces by forming a protective film adsorbed on these surfaces.

[0131] There is a wide variety of anti-wear additives. Preferably for the composition used according to the invention, the anti-wear additives are chosen from phosphosulfur additives such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or ZnDTP. The preferred compounds are of formula Zn((SP(S)(OR2)(OR3))2, in which R2 and R3, identical or different, independently represent an alkyl group, preferably an alkyl group comprising from 1 to 18 carbon atoms.

[0132] Amine phosphates are also anti-wear additives that can be used in a composition implemented according to the invention. However, the phosphorus provided by these additives can act as a poison for automobile catalytic systems because these additives generate ash. These effects can be minimized by partially substituting the amine phosphates with additives that do not provide phosphorus, such as, for example, polysulfides, in particular sulfur-containing olefins.

[0133] A lubricating composition used according to the invention may comprise from 0.01% to 6% by mass, preferably from 0.05% to 4% by mass, more preferably initially from 0.1% to 2% by mass, of anti-wear additives and extreme pressure additives, by mass relative to the total mass of composition.

[0134] A lubricating composition used according to the invention may comprise at least one friction-modifying additive. The friction-modifying additive may be chosen from a compound providing metallic elements and an ash-free compound. Among the compounds providing metallic elements, mention may be made of transition metal complexes such as Mo, Sb, Sn, Fe, Cu, Zn, the ligands of which may be hydrocarbon compounds comprising oxygen, nitrogen, sulfur or phosphorus atoms. The ash-free friction-modifying additives are generally of organic origin and may be chosen from monoesters of fatty acids and polyols, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, borate fatty epoxides; fatty amines or fatty acid glycerol esters. According to the invention, the fatty compounds comprise at least one hydrocarbon group comprising from 10 to 24 carbon atoms.

[0135] A lubricating composition used according to the invention may comprise from 0.01% to 2% by mass or from 0.01% to 5% by mass, preferably from 0.1% to 1.5% by mass or from 0.1% to 2% by mass of friction modifying additive, relative to the total mass of the composition.

[0136] Advantageously, a lubricating composition used according to the invention is free of friction modifying additive.

[0137] A lubricating composition used according to the invention may comprise at least one antioxidant additive.

[0138] The antioxidant additive generally makes it possible to delay the degradation of the composition in service. This degradation can notably result in the formation of deposits, the presence of sludge or an increase in the viscosity of the composition.

[0139] Antioxidant additives act in particular as radical inhibitors or hydroperoxide destroyers. Among the commonly used antioxidant additives, mention may be made of phenolic type antioxidant additives, amine type antioxidant additives, phosphosulfur antioxidant additives. Some of these antioxidant additives, for example phosphosulfur antioxidant additives, may be ash-generating. Phenolic antioxidant additives may be ash-free or in the form of neutral or basic metal salts. The antioxidant additives may in particular be chosen from sterically hindered phenols, sterically hindered phenol esters and sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted by at least one C1-C12 alkyl group, N,N'-dialkyl-aryl-diamines and mixtures thereof.

[0140] Preferably according to the invention, the sterically hindered phenols are chosen among the compounds comprising a phenol group of which at least one vicinal carbon of the carbon carrying the alcohol function is substituted by at least one Cr-Cio alkyl group, preferably a C1-C6 alkyl group, preferably a C4 alkyl group, preferably by the tert-butyl group.

[0141] Amino compounds are another class of antioxidant additives that can be used, optionally in combination with phenolic antioxidant additives. Examples of amine compounds are aromatic amines, for example aromatic amines of formula NR4R5R6 in which R4 represents an aliphatic group or an aromatic group, optionally substituted, R5 represents an aromatic group, optionally substituted, R6 represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R7S(O)ZR8 in which R7 represents an alkylene group or an alkenylene group, R8 represents an alkyl group, an alkenyl group or an aryl group and z represents 0, 1 or 2.

[0142] Sulfurized alkyl phenols or their alkali and alkaline earth metal salts can also be used as antioxidant additives.

[0143] Another class of antioxidant additives is that of copper compounds, for example copper thio- or dithio-phosphates, copper salts and carboxylic acids, dithiocarbamates, sulfonates, phenates, copper acetylacetonates. Copper I and II salts, succinic acid or anhydride salts can also be used.

[0144] A lubricating composition used according to the invention may contain any type of antioxidant additives known to those skilled in the art.

[0145] Advantageously, a lubricating composition used according to the invention comprises at least one ash-free antioxidant additive.

[0146] A lubricating composition used according to the invention may comprise from 0.5% to 2% by mass of at least one antioxidant additive, relative to the total mass of the composition.

[0147] A lubricating composition implemented according to the invention may also comprise at least one detergent additive.

[0148] Detergent additives generally make it possible to reduce the formation of deposits on the surface of metal parts by dissolving secondary oxidation and combustion products.

[0149] The detergent additives that can be used in a lubricating composition used according to the invention are generally known to those skilled in the art. The detergent additives may be anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic head. The associated cation may be a metal cation of an alkali or alkaline-earth metal.

[0150] The detergent additives are preferably chosen from alkali metal or alkaline earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates, as well as phenate salts. The alkali and alkaline earth metals are preferably calcium, magnesium, sodium or barium.

[0151] These metal salts generally comprise the metal in a stoichiometric quantity or in excess, therefore in a quantity greater than the stoichiometric quantity. These are then overbased detergent additives; the excess metal providing the overbased character to the detergent additive is then generally in the form of a metal salt insoluble in oil, for example a carbonate, a hydroxide, an oxalate, an acetate, a glutamate, preferably a carbonate.

[0152] A lubricating composition used according to the invention may, for example, comprise from 2% to 4% by mass of detergent additive, relative to the total mass of the composition.

[0153] A lubricating composition implemented according to the invention may also comprise at least one pour point lowering additive.

[0154] By slowing the formation of paraffin crystals, pour point depressant additives generally improve the cold behavior of the composition.

[0155] Examples of pour point lowering additives include polyalkyl methacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, alkylated polystyrenes.

[0156] Also, a lubricating composition implemented according to the invention may comprise at least one dispersing agent.

[0157] The dispersing agent may be chosen from Mannich bases, succinimides and their derivatives.

[0158] A lubricating composition used according to the invention may for example comprise from 0.2% to 10% by mass of dispersing agent, relative to the total mass of the composition.

[0159] A lubricating composition according to the invention may also comprise at least one viscosity index (VI) improving additive. Viscosity index improvers, in particular viscosity index improving polymers, make it possible to ensure good cold resistance and minimal viscosity at high temperature. Examples of viscosity index improving polymers include polymer esters, homopolymers or copolymers, hydrogenated or non-hydrogenated, of styrene, butadiene and isoprene, homopolymers or copolymers of olefin, such as ethylene or propylene, polyacrylates and polymethacrylates (PMA), preferably homopolymers or copolymers of olefin, such as ethylene or propylene.

[0160] In particular, a lubricating composition according to the invention may comprise from 0% to 15% by mass of additive(s) improving the viscosity index, preferably from 0% to 10% by mass, relative to the total mass of the lubricating composition.

[0161] A lubricating composition according to the invention may also comprise at least one dispersing agent. Such dispersing agents ensure the maintenance in suspension and the evacuation of insoluble solid contaminants constituted by the secondary oxidation products which form when the lubricating composition is in service. They may be chosen from Mannich bases, succinimides and their derivatives, such as polyisobutylene succinic anhydride derivatives.

[0162] In particular, a lubricating composition according to the invention may comprise from 0.2% to 10% by mass of dispersing agent(s), relative to the total mass of the composition.

[0163] It may also comprise at least one anti-corrosion agent or copper passivating agent, for example compounds such as succinic polyisobutene anhydrides, thiadiazole sulfonates or mercaptobenzothiazoles. They are typically present in a lubricating composition according to the invention at contents of between 0.01% and 1% by mass, relative to the total mass of the composition.

[0164] Preferably, a lubricating composition formulated based on ester(s) according to the invention has a kinematic viscosity measured at 40°C (KV40) according to the ASTM D445 standard ranging from 15 mm2 / s to 120 mm2 / s.

[0165] Preferably, a lubricating composition formulated based on ester(s) according to the invention has a kinematic viscosity measured at 100°C (KV100) according to the ASTM D445 standard ranging from 4 mm2 / s to 22 mm2 / s.

[0166] Preferably, the viscosity measured at high temperature and high shear, HTHS (for “High Temperature, High Shear”), measured at 150°C, is equal to or greater than 1.7 mPa.s, in particular between 1.7 and 3.7 mPa.s. The HTHS measurement is carried out at high shear (106 s1) and at 150°C according to the standardized methods CEC-L-36-A-90, ASTM D4683 or ASTM D4741.

[0167] Preferably, a lubricating composition formulated based on ester(s) according to the invention has a viscosity index ranging from 120 to 250.

[0168] The viscosity index is calculated by measuring the kinematic viscosities at 40°C and 100°C. Its method of calculation is described in the ASTM D2270 standard.

[0169] As mentioned above, the reduction in oil consumption associated with the formulation of the lubricant based on one or more esters according to the invention is decorrelated from the Noack volatility of the lubricating composition. Therefore, it is advantageously possible to access a lubricating composition having good properties in terms of low engine oil consumption, while having a Noack volatility and a viscosity simultaneously allowing good performance of Fuel Eco.

[0170] Advantageously, a lubricating composition according to the invention has a Noack volatility, determined according to the CEC L-040-093 (or ASTM D5800) standard, of from 10% to 60%, in particular from 12% to 40%.

[0171] The viscosity grade of a lubricating composition according to the invention may in particular be chosen from: - a grade according to the SAEJ300 classification defined by the formulas

[0172] 0W-(Y) 5W-(Y)

[0173] in which Y represents an integer ranging from 8 to 60, in particular ranging from 8 to 40 or from 12 to 40; or - a grade according to the SAEJ300 classification defined by the formulas

[0174] (X)W-8 (X)W-12

[0175] in which X represents an integer ranging from 0 to 25, in particular ranging from 0 to 20 or from 0 to 15.

[0176] According to a particular embodiment, the grade according to the SAEJ300 classification of a lubricating composition formulated according to the invention is chosen from OW-12, 0W-20, 5W-30, 5W-40 and 10W-40.

[0177] For example, the grade of a lubricating composition formulated according to the invention may be OW-12.

[0178] The present invention also relates to the use of a lubricating composition comprising at least one or more esters formed between a monoalcohol or polyalcohol, saturated or unsaturated, linear or branched, C1 to C16, and one or more monocarboxylic acids, saturated, linear or branched, C6 to C20,

[0179] to reduce the oil consumption of a thermal engine lubricated by means of said lubricating composition, in particular in a vehicle.

[0180] The present invention also relates to the use of a lubricating composition comprising at least:

[0181] - one or more esters formed between a monoalcohol or polyalcohol, saturated or unsaturated, linear or branched, C1 to C16, and one or more monocarboxylic acids, saturated, linear or branched, C6 to C20;

[0182] - one or more base oils, distinct from said ester(s), in particular chosen from group II and / or III base oils; in particular group III,

[0183] to reduce the oil consumption of a thermal engine lubricated by means of said lubricating composition, in particular in a vehicle.

[0184] The present invention also relates to the aforementioned use of a lubricating composition, wherein the ester or esters is(are) as defined above.

[0185] The present invention also relates to a method for reducing consumption of oil of a thermal engine, said method comprising a step of lubricating said engine with a lubricating composition based on one or more esters according to the invention.

[0186] All of the specificities described above relating to the lubricating composition in which said ester(s) are used apply to the uses and methods according to the invention.

[0187] The lubricating compositions used according to the invention find a particularly interesting application as lubricants for vehicle engines, in particular for heavy vehicles and light vehicles, in particular for heavy goods vehicles.

[0188] The present invention also describes the use of a lubricating composition as defined above, for lubricating the parts of an internal combustion engine.

[0189] The lubricating composition as defined above can be used to lubricate the parts of an internal combustion engine, preferably a hydrogen, gas, gasoline, diesel or even hybrid engine, and more particularly to lubricate the parts of a diesel engine.

[0190] The invention will now be described by means of the following examples given of course by way of illustration and not limitation of the invention. EXAMPLES

[0191] Example 1: Formulation of lubricating compositions Preparation of the compositions

[0192] Four lubricating compositions, CL1, CL2, CCI and CC2, were prepared by simple mixing, at room temperature, of the following components, in the mass proportions indicated in Table 2.

[0193] [Tables2] Components CCI CL1 CC2 CL2 Group II Base Oil 85.5 - - - Group III Base Oil - 20 89.7 20 Ester 1 (Propylene Glycol Diester) - 30.7 - 68.3 Ester 2 (2-Ethylhexyl Laurate) - 34.5 - - Pour Point Depressant (Acrylic Polymer) 0.3 0.3 0.3 0.3 Viscosity Index Improver (PISH Polymer) 4.2 4.5 - 1.4 Additive Package* 10 10 10 10

[0194] Table 2, Lubricating compositions tested

[0195] *includes an anti-wear agent, a dispersant, a detergent, an anti-foaming agent, an antioxidant.

[0196] Measurement of the rheological properties of lubricating compositions

[0197] Noack volatility was determined according to CEC L-040-093 standard.

[0198] The kinematic viscosities at 40°C and 100°C (KV40 and KV100) of the compositions prepared above were measured according to ASTM D445.

[0199] The viscosity index of the lubricating compositions was calculated from the kinematic viscosities at 40°C and at 100°C measured for each of the lubricating compositions.

[0200] The viscosity measured at high temperature and high shear, HTHS (for “High Temperature, High Shear”), was measured at 150°C according to ASTM D4683.

[0201] The BOV or "Base Oil Viscosity" in English, corresponds to the KV100 viscosity of the base oil or mixture of base oils. In the case of a mixture of base oils, the KV100 of the mixture of base oils is calculated according to the following equation (Arrhenius rule), for a mixture of 2 base oils:

[0202] log (visco mixture) = xi*log(viscol) +x2*log(visco2), with

[0203] visco mixture the viscosity of the mixture of oils 1 and 2,

[0204] visco 1 the viscosity of base oil 1, visco2 the viscosity of base oil 2,

[0205] Xi and x2 the respective molar fractions of base oil 1 and base oil 2 (Xj+X^l),

[0206] the same equation can be implemented and extrapolated for a mixture of n base oils.

[0207] The results are collected in the following table 3.

[0208] [Tables3] CCI CL1 CC2 CL2 Characteristics Noack Volatility (% by mass) 35.7 32.1 11.9 10.8 BOV (mm2 / s) 2.9 2.7 4.2 3.4 HTHS 150°C (mPa.s) 2.0 2.0 2.0 2.0 KV100 (mm2 / s) 6.04 5.37 5.62 5.01 KV40 (mm2 / s) 27.13 20.09 26.65 20.11 Viscosity Index 180 226 157 192

[0209] Table 3: Properties of the lubricants tested

[0210] It can be noted that the lubricants tested CCI and CL1 on the one hand, and the lubricants tested CC2 and CL2 on the other hand, have similar Noack viscosities. All of the lubricants tested also have the same HTHS viscosity values. The lubricants in this example correspond to an OW-12 grade according to the classification of the SAE J300 standard.

[0211] Example 2: Evaluation of oil consumption over an engine cycle

[0212] 2.1. Principle of the method for determining oil consumption

[0213] The method used to measure the oil consumption of the engine is based on the use of radiotracer compounds derived from Germanium-69 (69Ge). Such methods for determining the lubricating oil consumption of an engine, based on the use of radioactive tracers, are for example described in application WO 2004 / 23084 or in the publications of T. Delvigne et al. [6] and AE Gilles et al. [7]. Choice of radiotracers

[0214] The radiotracers are chosen so as to be representative of the distillation curve of the lubricant compositions studied. These radiotracers do not modify the intrinsic properties and are perfectly miscible with the tested lubricants. 69Ge emits gamma radiation from 511 keV to 1336 keV with a short half-life (39 hours), and can be combined with different organic compounds to obtain organic derivatives characteristic of the distillation curve of the base oil or mixture of base oils contained in the engine lubricant studied.

[0215] The four types of molecules labeled with Germanium-69 to represent oils are tetrapentylgermane (Gel, T°eb = 330°C), tetrahexylgermane (Ge2, T°eb = 385°C), tetraheptylgermane (Ge3, T°eb = 430°C) and tetraoctylgermane (Ge4, T°eb = 480°C).

[0216] Firstly, the distillation curves of each formulation were produced, according to a distillation process simulated by gas chromatography according to the ASTM D-228 standard, on the fractions of the base oils which make up each of the formulations studied.

[0217] The proportions of radiotracers are determined according to the distillation curve profile obtained, for each of the lubricating compositions tested, as specified in the following table.

[0218] [Tables4] Radiotracers (% by mass) CCI CL1 CC2 CL2 Gel 5 Ge2 45 55 5 25 Ge3 50 30 45 65 Ge4 15 50 10

[0219] Table 4, Composition (in mass %) of the mixtures of radiotracers added to the lubricating compositions

[0220] The mixture of radiotracers is then injected into the lubricant loads before the start of the tests, the overall quantity of radiotracers introduced into each of the lubricant compositions remains constant (20 mL of the mixture of radiotracers added to 24 L of lubricant tested, i.e. an addition of approximately 0.01% by volume of radiotracers), only the proportions within the mixture of radiotracers varying from one lubricant to another, in order to have a constant activity (20 MBq, i.e. 1000Bq / g of lubricant) for all the lubricants tested.

[0221] Homogenization of the lubricant labeled by the addition of the tracers is achieved by operating the engine for a short period of a few minutes after the addition of the radiotracers.

[0222] Device for determining oil consumption

[0223] The radioactive particle detection system comprises a system of filters and detectors sensitive to the radiation emitted by the radioactive tracers, at the exhaust line and at the outlet of the oil sump decanter.

[0224] The mixture of radiotracers injected into the lubricant charges is burned during the combustion of the lubricant during the engine test in proportion to the corresponding oil fractions, producing ash which is found in the combustion gases and which is trapped in the particulate filter systems. The filters used thus serve to trap the radiotracer residues whatever their combustion levels (burned in the form of germanium oxide (GeO2), partially burned or unburned in the form of germanium alkyl).

[0225] Particle filters make it possible to trap and accumulate these residues present in very small quantities compared to the combustion gases, in order to make the detection sufficiently sensitive to obtain a quantification of gamma emissions.

[0226] A first particulate filter system, installed downstream of the oil decanter, makes it possible to characterize the blow-by gases (also called crankcase gases, approximately 10% of the combustion gases) coming from leaks at the engine segmentation. A second particulate filter system (equipment composed of six particulate filters designed not to impact the proper engine operation), installed on the engine exhaust line, makes it possible to characterize the majority of the combustion gases (approximately 90%) emitted during combustion.

[0227] The detection devices integrate detectors sensitive to the radiation emitted by the radioactive tracers, and making it possible to evaluate the number of gamma rays detected as a function of time at the level of the particle filters, for a given engine operating point, with a given speed (rpm) and a given load (% of the maximum engine torque).

[0228] The oil consumption (g / h) can be directly deduced from the value of the slope (expressed in number of strokes / second per hour of engine operation) of the activity curve measured by the device, according to the following formula:

[0229] Oil consumption (g / h) = measured slope (Cps / h) * conversion factor (g / Cps)

[0230] with conversion factor (g / Cps) = 100 / (Specific activity (Bq / g) * Efficiency (Cps / 100 Bq),

[0231] the specific activity of each lubricant tested being known as indicated above and the effectiveness of each device being previously determined by calibration.

[0232] The total oil consumption value corresponds to the sum of the oil consumptions of each device.

[0233] 2.2, Engine test - determination of representative operating points of a WHTC motor cycle

[0234] The test vehicle used is a Medium-Duty engine with a displacement of 8L and a power of 320 horsepower. This engine includes all the latest technological advances in order to meet the EURO VI - Step e standard, which regulates pollutant emissions.

[0235] An evaluation of the oil consumption representative of a dynamic cycle “WHTC” (“Word Harmonized Transient test Cycle”) was carried out from the measurement of the oil consumption for thirteen stabilized engine operating points, previously chosen, so as to allow a good comparison of the oil consumption representative of a WHTC cycle.

[0236] The thirteen operating points are as follows, using the notation [Speed ​​(rpm)-Load (%)]: [1200-25%], [1600-25%], [1200-50%], [1600-50%], [2000-50%], [1200-75%], [1600-75%], [2000-75%], [1200-100%], [1400-100%], [1600-100%], [1800-100%], [2000-100%].

[0237] More particularly, these operating points were chosen following the complete mapping of 1003 points of the WHTC dynamic cycle, so as to be the most representative of the oil consumption during the WHTC cycle, to allow a homogeneous comparison according to the load or the engine speed and to study a fairly wide engine operating field.

[0238] [Fig. 1] [Fig. 1] represents the oil consumption for each of these thirteen engine operating points for composition CL1.

[0239] The oil consumption for each of the thirteen engine operating points can thus be determined with each of the lubricating compositions studied, as shown in [Fig.l] for composition CL1.

[0240] The thirteen oil consumption points obtained are then weighted, using empirical data, to obtain an oil consumption equivalent to what it would be in a dynamic WHTC type cycle.

[0241] The set of measurements is repeated twice.

[0242] As an example, the oil consumption results obtained for the thirteen engine operating points with the CL1 lubricant are shown in [Fig.l].

[0243] The results of the determination of the equivalent oil consumption for a WHTC dynamic cycle, obtained as described above, for each of the lubricating compositions, are gathered in the following table: Lubricating composition CCI CL1 CC2 CL2 Total oil consumption (g / h eq. WHTC) 7.8 5.1 5.5 4.4 (*)

[0244] (*' average value on the two measurement maps

[0245] It can be observed that, for lubricants having similar Noack volatilities (CCI and CL1, CC2 and CL2), the use of an ester or mixture of esters according to the invention makes it possible to significantly reduce oil consumption on an engine cycle, compared to lubricants based on group II or group III base oils, and devoid of esters according to the invention. References

[0246] [1] Vicente Macian et al., Tribology International, vol.79, 2014, pages 132-139;

[0247] [2] MJS de Carvalho et al., Tribology International, vol.43, issue 12, 2010, pages 2298-2302;

[0248] [3] Anderson and Guinther, “Engine Oil Fuel Economy: Benefits and Potential Flow Rates of Low Viscosity Engine Oil," SAE Int. J. Adv. & Curr. Prac. in Mobility 2(1):368-375, 2020;

[0249] [4] Koyama et al. "Research on Ultra-High Viscosity Index Engine Oil: Part 2 - Influence of Engine Oil Evaporation Characteristics on Oil Consumption of Internai Combustion Engines," SAE Int. J. Adv. & Curr. Prac. in Mobility 4(4):1217-1227, 2022 ;

[0250] [5] Review of Oil Consumption Aspects of Engines, D.C. Roberts, Engine Oils and Automotive Lubrication;

[0251] [6] Delvigne et al., « A New Methodology for On-Line Lubricant Consumption Mea- surement », Journal of fuels and lubricants (2005), vol. 114, Section 4, pp. 1028-1033;

[0252] [7] A-E Gilles, « Influence of Lubricant Formulations on Engine Oil Consumption using Radionuclide Technique », SAE International in US, 2007-01-1981.

Claims

Claims

1. Use of at least one ester in a lubricating composition dedicated to a thermal engine, in particular in a vehicle, to reduce the oil consumption of the engine, said ester(s) being formed between a monoalcohol or polyalcohol, saturated or unsaturated, linear or branched, C1 to C16, and one or more monocarboxylic acids, saturated, linear or branched, C6 to C20.

2. Use according to the preceding claim, for extending the drain interval.

3. Use according to claim 1 or 2, for reducing engine oil consumption while maintaining good engine fuel economy properties or Fuel Eco properties.

4. Use according to any one of the preceding claims, for reducing oil consumption, estimated on the basis of a WHTC engine cycle, by at least 20%, in particular by at least 35%, compared to the engine oil consumption obtained with an ester-free lubricating composition as defined in claim 1, in particular based on group II or III base oils, and having a Noack volatility, measured according to CEC standard L-040-093, equivalent to plus or minus 15% relative variation.

5. Use according to any one of the preceding claims, in which said ester(s) are used in an amount of at least 15% by mass, in particular from 20% to 80% by mass, in particular from 30% to 70% by mass, relative to the total mass of said lubricating composition.

6. Use according to any one of the preceding claims, in which the ester is chosen from monoesters and diesters formed between a monoalcohol or a dialcohol, saturated or unsaturated, preferably saturated, linear or branched, C1 to C12, in particular C2 to C10, and one or more monocarboxylic acids, saturated, linear or branched, in particular linear, C8 to C16.

7. Use according to any one of the preceding claims, in which the ester is chosen from: (i) monoesters formed between a branched, saturated or unsaturated, preferably saturated, C4 to C16, in particular C6 to C12, monoalcohol and a saturated, linear or branched, preferably linear, C6 to C20, in particular C8 to C16, monocarboxylic acid; (ii) diesters formed between a linear or branched, saturated or unsaturated, preferably saturated, C1 to C6, in particular C1 to C4, dialcohol and one or more saturated, linear or branched, preferably linear, C6 to C20, in particular C8 to C16, monocarboxylic acids; and mixtures thereof.

8. Use according to any one of the preceding claims, in which the ester is chosen from: (i) the monoesters of the following formula (I): R“-C(O)-O-CH2-CH(R2)-R1 (I) in which: - Ra represents a saturated, linear or branched, preferably linear, hydrocarbon group comprising from 7 to 15 carbon atoms, preferably from 8 to 12 carbon atoms; and - R1 and R2 represent, independently of each other, a linear or branched, saturated or unsaturated, preferably saturated, C1 to C5 hydrocarbon group, or a hydrogen atom; (ii) the diesters of the following formula (II): Rb-C(O)-O-([C(R3)2]nO)sC(O)-Rc (II) in which: - Rb and Rc, identical or different, represent saturated, hydrocarbon groups, linear or branched, preferably linear, comprising from 7 to 15 carbon atoms, preferably from 8 to 12 carbon atoms;- R3 represent, independently of each other, a hydrogen atom or a linear or branched (Ci-C5)alkyl group, in particular a methyl, ethyl or propyl group, in particular methyl; - s is 1 or 2; preferably s is 1; - n is 1, 2 or 3; it being understood that, when s is different from 1, n may be identical or different; and mixtures thereof.;

9. Use according to any one of the preceding claims, in which the ester is chosen from monoesters and diesters formed from a saturated and branched C5 to C10 monoalcohol, for example 2-ethylhexanol, or a saturated, branched or linear C2 to C5 dialcohol, for example propylene glycol, and one or more saturated and linear C8 to C14, in particular C9 to C12, monocarboxylic acids, and mixtures thereof.

10. Use according to any one of claims 1 to 8, in wherein the lubricating composition comprises a single ester as defined in any one of claims 1 and 6 to 9, in particular a diester as defined in any one of claims 6 to 9, and more particularly a diester of formula (II) according to claim Q

11. O. Use according to any one of claims 1 to 9, in which the lubricating composition comprises a mixture of at least one monoester, in particular of formula (I) and at least one diester, in particular of formula (II) as defined in claim 8, preferably in a diester(s) / monoester(s) mass ratio strictly greater than 1, in particular between 1.1 and 1.

5.

12. Use according to any one of the preceding claims, in which the lubricating composition comprises at least 10% by mass, in particular from 5% to 75% by mass, and more particularly from 20% to 60% by mass, of one or more base oils, distinct from said ester(s), relative to the total mass of said lubricating composition, said base oil(s) being more particularly chosen from group II and / or group III base oils.

13. Use according to any one of the preceding claims, wherein the lubricating composition further comprises one or more additives selected from friction modifying additives, anti-wear additives, extreme pressure additives, detergents, antioxidants, viscosity index improvers, pour point depressants, dispersants, thickeners, corrosion inhibitors, copper passivators and mixtures thereof.

14. Use according to any one of the preceding claims, in which the lubricating composition has a Noack volatility, determined according to CEC standard L-040-093, of from 10% to 60%, in particular from 12% to 40%.

15. Use according to any one of the preceding claims, wherein the lubricating composition has a kinematic viscosity measured at 100°C (KV100) according to ASTM D445 ranging from 4 mm2 / s to 22 mm2 / s.

16. Use of a lubricating composition comprising one or more esters formed between a monoalcohol or polyalcohol, saturated or unsaturated, linear or branched, C1 to C16, and one or more monocarboxylic acids, saturated, linear or branched, C6 to C20. to reduce the oil consumption of a thermal engine lubricated with means of said lubricating composition, in particular in a vehicle.

17. Use of a lubricating composition according to the preceding claim, wherein the ester or esters are as defined in any one of claims 5 to 11.

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