FR2924439A1 - LUBRICATING COMPOSITION FOR FOUR-STROKE ENGINE WITH LOW ASH RATES - Google Patents

Abstract

The present invention relates to a lubricant composition for a low ash four-stroke engine comprising: a) one or more base oils selected from Group I to V oils, preferably from Group III or IV oils of the API classification. b) at least one compound (b) chosen from the group of heavy PAOs having a kinematic viscosity at 100 ° C. of between 75 and 3000 ° C., or in the group of polyisobutene (PIB) type polynomeric compounds, or a mixture thereof , etc.) at least one ester of formula R (OH) m (COOR '(OH) p) n in which m is an integer from 0 to 8, preferably from 1 to 4, n is an integer of 1 to 8, preferably from 1 to 4 and p is an integer from 0 to 8, preferably from 1 to 4 and where the sum p + m is strictly greater than zero, R and R 'independently represent one of the another a linear or branched, saturated or unsaturated hydrocarbon group, optionally substituted by one or more their aromatic groups. and having 1 to 30 carbon atoms, and its borated derivatives, said composition having a sulfated ash level of less than or equal to 0.5% measured according to ASTM D874 standard, a phosphorus level of less than or equal to 500 ppm measured according to ASTM D5185 standards, and a sulfur content of less than 0.2% measured according to ASTM D5185. The composition has good detergency properties, the use of which promotes fuel economy.

Description

LUBRICATING COMPOSITION FOR FOUR-STROKE ENGINE WITH LOW ASH RATES.

Field of the invention

The present invention relates to a lubricant composition for a low ash four-stroke engine having good detergency properties, the use of which promotes fuel economy and comprises at least one hydroxyl ester or derivative thereof. Technological Background of the Invention

Due to environmental concerns, there is increasing interest in reducing pollutant emissions and fuel savings in vehicles. The nature of the engine lubricant has an influence on these two phenomena. On the one hand, the lubricant's behavior in reducing friction will have an impact on fuel consumption. It is primarily the quality of the lubricating bases, alone or in combination with viscosity index improvers and friction modifier additives, which gives the lubricant its fuel eco properties. On the other hand, because of the dilution of the fuel by a portion of the engine lubricant, some components of the lubricant will end up, after combustion, in the vehicle exhaust. These components, in particular certain additives, can generate sulfur, phosphorus, sulphated ash which will damage the post-treatment systems installed on the vehicles. Ashes are harmful to particulate filters and phosphorus acts as a poison for catalytic systems.

It will therefore be sought, in engine applications, to adapt accordingly the lubricant formulations, whether in the choice of lubricant bases or additives. For automotive engines, the use of lubricants specifically formulated in compliance with certain specifications, in particular the low ash specifications ACEA-C4 (so-called low saps), or ACEA-CI (so-called low saps and fuel eco ), developed by the Association of European Automobile Manufacturers. These specifications impose lubricant limits on sulphated ash (generated by the presence of metals), sulfur and phosphorus, hence the name low saps for Sulfated Ashes, Phosphorus, Sul fur .. Lower ash content, sulfur and phosphorus in engine lubricants maintaining the required high performance levels is a challenge as these elements are present in the most commonly used base oils and additives, for example detergent additives, avoiding the formation of deposits on the surface. metal parts by dissolving oxidation and combustion by-products, which are key compounds in the formulation of a motor oil, contain metal salts which generate ash, usually sulphonates, phenates, salicylates of metals alkalis such as calcium, magnesium, overbased or not, in order to lower the rate of lubricant detergents to In order to reduce its ash content, while maintaining an adequate cleanliness of the engine parts, it is necessary to act on the ability of the other lubricant compounds to form a minimum of deposits. A possible way to obtain lubricants with low ash content, maintaining a good detergency behavior despite a reduced rate of detergent, and having good fuel eco properties, is to favor the use of certain unconventional mineral base oils or synthetic bases.

These bases have the advantage of better resistance to temperature and resistance to oxidation compared to conventional bases, which minimizes the formation of deposits. It is thus possible to lower the rate of treatment of the lubricants with detergent and to lower the ash content. Their naturally high viscosity index (VI) leads to lubricants with good fuel eco properties, and makes it possible to limit the amount of VI improving polymers that generate deposits in lubricants. In addition, the sulfur content of unconventional mineral bases is comparatively lower than that of conventional mineral bases because they undergo extensive hydrotreatment, and the synthetic bases are free of sulfur, which facilitates compliance with the sulfur limits imposed by ACEA specifications. Unconventional mineral bases are group III bases according to the American Petroleum Institute (API) classification. having a high viscosity index value VI (typically greater than 130), commonly referred to as Group III + bases, or bases derived from GTL (Gas to Liquid) processes. The unconventional mineral bases called Group III + are prepared in order to improve their cold properties, to reduce their volatility and to increase their viscosity index (VI), to reach values greater than 130. These are hydroisomerized bases, which can be prepared from residues resulting from hydrocracking treatment, optionally with the addition of waxes or slack wax, and subjected to a high catalytic dewaxing.In the following description, and in the absence of precision, the term group III bases refers to any type of Group III mineral base according to the API classification, while the term unconventional Group III base, or Group III + base refers to Group III bases of VI greater than] 30. Synthetic bases are, for example, polyalphaolefins, esters and Poly internat olefins (respectively Group 1V, V and V according to the API classification). Despite their advantages, the aforementioned bases require a number of complex refining operations for groups III +, and synthesis for groups IV and V, which affects their price and availability.

The present invention relates to lubricant compositions for a four stroke engine, low saps and fuel eco, comprising an additivation system allowing the use of a larger number of lubricating bases, including in particular conventional Group III bases. Summary of the invention.

The subject of the present invention is lubricant compositions for a four-stroke engine, containing additives that in themselves provide a minimum of ash, sulfur and phosphorus, totally or partially substituting for conventional additives used in this type of application, and which, in combination with each other, allow said lubricant compositions to retain detergency properties and eco-optimal fuel with a low or very low rate of ash, sulfur, phosphorus. When it comes to preserving or improving the detergency properties of a lubricant, it is particularly, at constant detergent rate, to minimize the formation of deposits by the various components of the lubricant, including high temperature deposits. The compositions according to the invention are lubricating compositions for a four-stroke engine comprising: a) one or more base oils chosen from oils of group I to V, preferably from oils of group III or IV of the API classification. b) at least one compound (b) chosen from the group of heavy PAOs, with a kinematic viscosity at 100 ° C of between 75 and 3000 ° C, or in the group of polyisubutene (PIB) type polymeric compounds, or a mixture thereof and c) at least one ester of formula R (OH) n, (COOR '(OH) p) n in which m is an integer from 0 to 8, preferably from 1 to 4, n is an integer of 1 to 8, preferably 1 to 4 and p is an integer of 0 to 8, preferably 1 to 4 and where the sum p + m is strictly greater than zero, R and R 'independently represent one of the other a linear or branched, saturated or unsaturated hydrocarbon group, optionally substituted with one or more aromatic groups, and comprising from 1 to 30 carbon atoms, and its borated derivatives; said composition having a sulphated ash content of less than or equal to 0.5% measured according to ASTM D874 standard, a phosphorus level of less than or equal to 500 ppm measured according to ASTM D5185 standard, and a sulfur content of less than 0.2% measured according to ASTM D5185. According to a preferred embodiment, the ester (c) contains at least one free OH hydroxyl group belonging to the R group, said OH group being located in the alpha, beta or gamma position with respect to the carbon of the CO function of a function ester on which the group R is attached, and / or contains at least one free OH hydroxyl group belonging to the group R 'said OH group being located in the beta, gamma or delta position with respect to the COO group oxygen of a function ester on which the group R 'is attached. Preferably, the group R 'of the ester (c) represents a C 1 to C 10, preferably C 2 to C 6, group.

According to one embodiment, p is strictly greater than zero and the group R of the ester (e) represents a C8 to C2 group, preferably a C12 to C18 group. Preferably, at least one ester (c) will be selected from the monoesters or diesters of glycerol, preferably chosen from glycerol monoleate, glycerol stearate or isostearate and their borated derivatives. According to one embodiment, n is an integer between 1 and 4 and the group R of the ester (c) represents a C 1 to C 5 group, preferably C 1 to C 3. Preferably, at least one ester (c) is chosen from citrates, tartrates, malates, lactates, mandelates, glycolates, hydroxypropionates, hydroxyglutarates or their borated derivatives. The composition according to the invention leads to a minimum fuel economy measured on test M111 FE of at least 2.5% and satisfying the specifications ACEA-C 1 defined by the Association of European Automobile Manufacturers. According to a preferred embodiment, the composition has a kinematic viscosity at 100 ° C., measured by the ASTM D445 standard of between 5.6 and 16.3 Cst, preferably between 9.3 and 12.5 Cst. According to a preferred embodiment, the composition has a grade 5W30 according to the classification SAEJ300. According to a preferred embodiment, the composition has a VI viscosity index greater than or equal to 130, preferably greater than 150, preferably greater than 160.

According to a preferred embodiment, in the composition, the base oil or the base oil mixture (a) represents at least 70% by weight of said composition. According to a preferred embodiment, in the composition, the base oil or the mixture of base oils (a) comprises: at least 60% by weight, relative to the total weight of lubricant, of one or more base oils Group III - at least 10% by weight, based on the total weight of lubricant, of one or more Group IV base oils. According to one preferred embodiment, the composition comprises a compound (b) chosen from the group of heavy PAOs, and a compound (b) chosen from the group of polymeric compounds of the PIB type. According to one preferred embodiment, the composition comprises from 0.1 to 6%, preferably from 2 to 4% of at least one compound (b) and from 0.1 to 2.5%, preferably from 0.5 to 1.5%. % of at least one compound (c). P It r. 1. According to one preferred embodiment, the composition comprises at least one anti-wear compound of the Zith dithiophosphate type, in optional combination with an amine phosphate.

According to one preferred embodiment, the composition comprises at least one anti-wear compound of the type of Zinc dithiophosphates in an amount of less than or equal to 1%, preferably less than or equal to 0.5%. In a preferred embodiment the composition is free of amine phosphate additive.

In a preferred embodiment the composition is free of Molybdenum friction modifier additive. According to one preferred embodiment, the composition comprises at least one antioxidant compound, preferably without ash, preferably of phenolic or amine type.

In a preferred embodiment the composition comprises from 0.01 to 5% of one or more antioxidant additives. According to one preferred embodiment, the composition has a BN, determined according to the ASTM D 2896 standard, less than or equal to 8 milligrams of potassium hydroxide per gram of lubricant, preferably less than or equal to 6.5 milligrams of potassium per gram of lubricant. comprises between 0 and 3%, preferably between 0 and 2.5% of an improvement polymer of VI selected from among polymeric esters, copolymer olefins (OCP), homopolymers or copolymers of styrene, butadiene or isoprene polymethacrylates (PMA).

According to another subject, the invention relates to a process for the manufacture of a composition according to the invention by diluting an additive package comprising at least one compound (b) and at least one compound (c), in an oil base or a mixture of base oils (a), and optionally adding a VI improving polymer.

According to a preferred embodiment, the additive package is diluted to represent from 10 to 30%, preferably from 15 to 20% by weight of the lubricating composition, and wherein the VI improving polymer represents from 0 to 3% by weight. of the lubricating composition. R Hic •. and. Another object of the invention is to provide a package of additives for four-stroke engine lubricant having a sulfated ash level. less than or equal to 0.5% according to ASTM D874, a phosphorus level of less than or equal to 500 ppm measured according to ASTM D5185, and a sulfur content of less than 0.2%, measured according to ASTM D5185, characterized in that it comprises: - at least one compound (b), heavy PAO and / or (PIB) - at least one hydroxylated ester (c) - optionally, anti-wear and extreme pressure additives, friction modifiers, detergents, antioxidants, overbased or non-overbased detergents, pour point depressants, dispersants, anti-foam additives, thickeners, viscosity index improvers, etc. Preferably, the additive package comprises: from 0.5 to 30% by weight, preferably from 10 to 25% by weight, of at least one compound (b), heavy PAO and / or (PIB) - from 0.5 to 15% by weight, preferably from 2.75 to 8.75% by weight of at least one hydroxylated ester (c). According to another object, the invention relates to the use of a composition according to the invention as a lubricant for a four-stroke engine. According to another subject, the invention relates to the use of at least one ester of formula R (OH) n, (COOR '(OH) p) in which m is an integer from 0 to 8, preferably from 1 to 4, n is an integer from 1 to 8, preferably from 1 to 4 and p is an integer from 0 to 8, preferably from 1 to 4 and where the sum p + m is strictly greater than zero, R and R 'represent, independently of each other, a saturated or unsaturated linear or branched hydrocarbon group, optionally substituted by one or more aromatic groups, and comprising from 1 to 30 carbon atoms, and its borated derivatives, as a friction modifier for the preparation of a four-stroke lubricant composition having a sulfated ash content of less than or equal to 0.5% measured according to ASTM D874, a phosphorus level of less than or equal to 500 ppm measured according to ASTM D5185, and a sulfur level less than or equal to 0.2% measured according to e ASTM D5185. DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION The lubricating composition for a four-stroke engine according to the invention has a sulfated ash content of less than or equal to 0. The composition of the invention is as follows: ## STR1 ## , 5% measured according to ASTM D874, a phosphorus level less than or equal to 500 ppm measured according to ASTM D5185, and a sulfur content of less than 0.2% measured according to ASTM D5185.

Preferably, the compositions according to the present invention are of ACEA C4 type, preferentially ACEA-Cl, according to the specifications established by the European Association of Automobile Manufacturers for gasoline and diesel engine oils for light vehicles. The table below lists the sulfur, phosphorus and sulphated ash content and the fuel economy performance required by these specifications. ACEA-ACEA-ACEA-ACEA-Cl C2 C3 C4 Maximum Ash Content 0.5% 0.8% 0.8% 0 Sulphated% (ASTM D874), 5% Maximum Sulfur Content% 0.2% 0.32 % 0.3% 0.2% (ASTM D 4294) Maximum Phosphorus Content 500 ppm 900 ppm 900 ppm 500 ppm (ASTM D5185) Minimum fuel economy 2.5% 2.5% 1% 1 0/0 (measured on engine test M1 1 IFE, CEC L54-T-96) According to one embodiment, the compositions according to the present invention have a sulphated ash content less than or equal to 0.30%, preferably less than or equal to 0.25. %, and a phosphorus content of less than or equal to 300 ppm, preferably less than or equal to 200 ppm. 1) Base oils or base oil mixture (a) The lubricating compositions according to the present invention comprise one or more base oils, generally representing at least 50% by weight of the lubricating compositions, generally greater than 70% and up to 90% and more.

The base oil (s) used in the compositions according to the present invention may be oils of mineral or synthetic origin of groups I to V according to the classes defined in the API classification (or their equivalents according to the ATIEL classification) as summarized herein. below, alone or mixed. Saturated content Content in Viscosity index sulfur Group I Mineral oils <90%> 0.03% 80 S VI <120 Group II Oils> _ 90% 0.03% 80 VI <120 hydrocracked Group III 90% 0.03% 120 Hydrocracked or hydrophilic oils isomerized Group IV PAO Polyalphaolefins Group V Esters and other bases not included in bases groups I to IV These oils may be oils of vegetable, animal or mineral origin. The mineral base oils according to the invention include all types of bases obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, desalting, solvent dewaxing, hydrotreatment, hydrocracking and hydroisomerization. , hydrofinishing. The base oils of the compositions according to the present invention may also be synthetic oils, such as certain esters of carboxylic acids and alcohols, or polyalphaolefins. The polyoa-olefins used as base oils, and which are distinguished from the heavy polyalphaolefins (b) also present in the compositions according to the present invention, are for example obtained from monomers having from 4 to 32 carbon atoms (for example octene, decene), and a viscosity at 100 ° C of between 1.5 and 15 Cst. Their weight average molecular weight is typically between 250 and 3000. Mixtures of synthetic and mineral oils may also be employed. There is no limitation to the use of this or that base oil for producing the compositions according to the present invention, except that their quantity and their nature

P (3: e ~ cis'6l pu'n C'-i ~ u: _ • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •• sulfur less than 0.2% measured according to ASTM D 5185, a viscosity grade and Viscosity Index or VI values compatible with use as a four-stroke engine oil.

Preferably, the compositions according to the present invention have a kinematic viscosity at 100 ° C. of between 5.6 and 16.3 Cst, measured by the ASTM D445 standard (grade SAE 20, 30 and 40), preferably between 9.3 and 12.5 Cst (grade 30). According to a particularly preferred embodiment, the compositions according to the present invention are grade 5W30 according to the SAEJ300 classification.

The compositions according to the present invention also preferably have a VI viscosity index greater than 130, preferably greater than 150, preferably greater than 160. The predominant effect on the sulfur content of the lubricants is obtained by acting on the sulfur content of the base oils used: this is why it is advantageous to use base oils having a sulfur content of less than 0.3%, for example Group III mineral oils, and synthetic bases which are free of sulfur, preferably of group IV, or their mixture. Thus, the compositions according to the present invention may contain at least 70% base oil, typically at least 60% by weight of one or more Group III base oils and at least 10% by weight of one or more several Group IV base oils. 2) The compounds (b) polyalphaolefines (PAO) heavy or polyisobutenes (PIB). The compounds (b) of heavy polyalphaolefin (PAO) type or polyalphaolefinic viscosity used in the composition according to the invention are chosen from PAOs of kinematic viscosity at 100 oc measured according to ASTM D445 between 75 and 3000 is, preferably between 150 and 1500, preferably between 300 and 1200 cSt. Their number-average molecular weight, Mn is preferably greater than 2500, typically between 3000 and 20000, preferentially between 3000 and 10000, preferably between 3000 and 7000. R Hfe this 1, 26111rr.l ° 0-L ',, rP irR Their molecular weight in weight Mw is typically in the range of about 4000 to about 50000, and their polydispersity index Mw / Mn is in the range of about 1.1 to about 5 and higher. These polyalphaolefins are for example obtained from monomers such as octene, decene, dodecene, tetradecene, hexadecene, etc., alone or mixed with other olefins. They can be used alone or as a mixture in the compositions according to the invention. The compounds (b) of polyisobutene type (PIB) used in the composition according to the invention are oil-soluble liquid polymeric compounds. Their molecular weight in weight Mw is typically greater than 800, typically between 800 and 8000, usually between 1500 and 7000. Their kinematic viscosity at 100 ° C is preferably between 1000 and 6000 cst (ASTM D445).

Typically, the PIBs according to the present invention have a weight-average molecular weight of between 2000 and 5000 and a kinematic viscosity at 100 ° C of between 3000 and 4500 Cst. The composition may comprise at least one compound chosen from the group of heavy PAOs described above, and / or at least one compound chosen from the group of the PIB-type polymeric compounds described above, or a mixture thereof. These compounds (b), alone or as a mixture, totally or partially substitute for the VI-improving polymers which are usually present in engine lubricants formulated with conventional bases. They therefore allow a lowering of the detergent rate. However, the performances in fuel eco are a little degraded, because of their bad cold behavior. 3) Hydroxyl esters (c) The composition further comprises at least one ester of formula R (OH) m (COOR '(OH) p) in which m is an integer from 0 to 8, preferably from 1 to 4, n is an integer from 1 to 8, preferably from 1 to 4 and p is an integer from 0 to 8, preferably from 1 to 4 and where the sum p + m is strictly greater than zero, R and R ' are independently of each other a linear or branched, saturated or unsaturated hydrocarbon group, optionally substituted with one or more C 1 -C 10 -Lo-sco, or aromatic groups, and having from 1 to 30 atoms; of carbon, and its borated derivatives. According to a preferred embodiment, the ester (c) at least one free OH hydroxyl group belonging to the R group, said OH group being located in the alpha, beta or gamma position with respect to the carbon of the CO function of an ester function on which the R group is attached, and / or contains at least one free OH hydroxyl group belonging to the R 'group, said OH group being located in the beta, gamma or delta position with respect to the oxygen of the COO group of an ester function on which the group R 'is attached.

Preferably R 'represents a C1 to C10 group, preferably a C2 to G. R preferably represents a C8 to C25 group, preferably a C12 to C18 group. According to a preferred embodiment, p is strictly greater than zero when the R group of the ester (c) represents a C8 to C25 group, preferably a C12 to C18 group.

According to another embodiment n is an integer between 1 and 4 when the group R of the ester (c) represents a group C1 to C5, preferably C1 to C3. The hydroxylated esters (c) may be chosen from monoesters or diesters obtained from glycerol such as glycerol monoleate, glycerol stearate or isostearate and their borated derivatives. The hydroxylated esters (c) may also be chosen from citrates, tartrates, malates, lactates, mandelates, glycolates, hydroxypropionates, hydroxyglutarates or their borated derivatives. Surprisingly, the Applicant has demonstrated that the use of the compounds (c), in combination with the compounds (b), made it possible to formulate, from conventional bases, engine lubricants of good fuel eco performance, and good detergency properties, even though the detergent level remains moderate. This produces fuel eco engine lubricants, Iow saps, and retaining good property detergency.

The compositions according to the invention may comprise, for example, from 0.1 to 6%, preferably from 2 to 4% of at least one compound b) and from 0.1 to 2.5%, preferentially from 0.5 to 1.5%. % of at least one compound (c). R. Brereis161RO '61T_- ~ t ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~, The esters of formula R (OH) m (COOR' (OH) p) n according to the invention are prepared according to known methods those skilled in the art, in particular by reacting a carboxylic acid of formula R (OH) m (COOH) with an alcohol of formula R '(OH) p, the substituents R, R', and the indices m, n being as defined above. 4) Other additives The compositions according to the invention may further contain any type of additive suitable for use as a four-stroke engine oil. These additives may be introduced individually and / or included in packages of additives used in commercial four-stroke engine lubricant formulations, with performance levels as defined by ACEA (Association of European Automobile Manufacturers) and / or the API (American Petroleum Institute) well known to those skilled in the art. Thus, the compositions according to the invention may contain, in particular and without limitation, anti-wear and extreme pressure additives, friction modifiers, antioxidants, overbased or non-overbased detergents, viscosity index improvers, point improvers. flow, dispersants, antifoam, thickeners ... The anti-wear and extreme pressure additives protect the friction surfaces by forming a protective film adsorbed on these surfaces. The most commonly used is Zinc di thiophosphate or DTPZn. This category also contains various phosphorus, sulfur, nitrogen, chlorine and boron compounds. There is a wide variety of anti-wear additives, but the most used category in motor oils is that of phospho-sulfur-containing additives such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or DTPZn. The preferred compounds have the formula Zn ((SP (S) (OR 1) (OR 2)) 2, where R 1 and R 2 are alkyl groups, preferably containing from 1 to 18 carbon atoms. in the range of 0.1 to 2% by weight in the motor oils.

Amine phosphates are also commonly used anti-wear additives. However, the phosphorus provided by these additives acts as poison catalytic systems of automobiles, and they also bring ash. It is possible to minimize these effects by partially substituting phosphorus-free additives, such as, for example, polysulfides, in particular sulfur-containing olefins In the lubricating compositions, nitrogen-containing and sulfur-containing anti-wear and extreme pressure additives, such as, for example, metal dithiocarbamates, in particular ash-forming dithiocarbamate, which are also ash generators, are also usually encountered. Glycerol esters are also anti-wear additives, for example mono-, di- and trioleate monopalmitates and monomyristates.The anti-wear and extreme-pressure additives are present in the compositions for motor lubricants at contents of between 0.01 and 6. %, preferably between 0.01 and 4% In the compositions according to the invention, the presence of hydroxylated esters or polyalcohol esters (c) makes it possible to limit the amount of additives sulfur, phosphorus, nitrogen and sulfur, phosphates, so as to achieve low levels of sulfated ash, sulfur and phosphorus, for example compatible with the ACEA-C and ACEA-C2 specifications, while maintaining performance compatible with use as a four-stroke engine oil. The lubricating compositions according to the present invention may contain DTPZN, and / or other antiwear and extreme pressure additives, in amounts compatible with an overall sulfated ash content of less than 0.5% measured according to ASTM D874, a phosphorus level below 500 ppm measured according to ASTM D5I85, and a sulfur content of less than 0.2% measured according to ASTM D 5185. They may contain a level of DTPZn of less than or equal to 1% by weight, preferably less than or equal to equal to 0.5%. They may also be free (0% by weight) of additives providing phosphorus, for example amine phosphates. The friction modifiers encountered in the four-stroke lubricant compositions may be compounds providing metallic elements or ash-free compounds. Solid compounds such as molybdenum sulfide, graphite or PTFE are also found. The metal compounds are, for example, transition metal complexes such as Mo, Sb. Sn, Fe, Cu, Zn, the ligands of which may be hydrocarbon compounds containing oxygen, nitrogen, sulfur or R-Bre, 26100 203., or irpo, 1'1306 phosphorus. In particular, the molybdenum-containing compounds can be particularly effective, such as, for example, dithiocarbamates, molybdenum dithiophosphates. The ashless friction modifiers can be, for example, fatty alcohols, fatty acids, esters, fatty amines. Friction modifying additives are generally present at levels of between 0.01 and 5%, preferably 0.01 and 1.5%, in engine lubricants. In the compositions according to the invention, the presence of hydroxylated esters or of polyalcohol esters (c) makes it possible to limit the amount of friction modifiers that bring in sulfated ash, phosphorus and sulfur, so as to attain a low ash content. sulfates, sulfur and phosphorus, for example compatible with the specification ACEA-C1 and ACEA-C4, while maintaining performance compatible with use as four-stroke engine oil, including fuel eco or fuel-saving properties, so as to The compositions according to the present invention may be free of ash-providing friction modifiers, for example molybdenum friction modifiers.

The lubricating compositions according to the present invention may, however, contain all types of friction-modifying additives, in amounts compatible with an overall level of sulfated ash of less than or equal to 0.5%, measured according to ASTM D874, a lower phosphorus level. or equal to 500 ppm measured according to ASTM D5185, and a sulfur content of 0.2% or less measured according to ASTM D 5185. Antioxidants delay the degradation of oils in service, degradation which can result in the formation of deposits , the presence of sludge, or an increase in the viscosity of the oil. They act as free radical inhibitors or destroyers of hydroperoxides. Among the antioxidants commonly used are the antioxidants of the phenolic type, amines. Some of these additives. for example phospho sulfur, can be ash generators. Phenolic anoxidants may be ashless, or may be in the form of neutral or basic metal salts. Typically, they are R Br compounds. e1._61nn: 1, 'n ~., euu .ri (13 (, I31, Ioc containing a sterically hindered hydroxyl group, for example when 2 hydroxyl groups are in the o or p position of each other, or that the phenol is substituted by an alkyl group having at least 6 carbon atoms The amino compounds are another class of antioxidants which may be used, optionally in combination with phenolics Typical examples are aromatic amines of the formula R 8 R 9 R 10 N, where R8 is an aliphatic group, or an optionally substituted aromatic group, R9 is an optionally substituted aromatic group, R10 is hydrogen, or an alkyl or aryl group, or a group of formula R11S (O), R12, where R11 is a alkylene, alkenylene, or aralkylene group, and x is 0, 1, or 2. Sulfurized alkyl phenols or their alkali and alkaline earth metal salts are also used as antioxidants.Another class of antioxidants is e oil-soluble copper compounds, for example copper thio or dithiophosphate, copper and carboxylic acid salts, dithiocarbamates, sulphonates, phenates, copper acetylacetonates. Copper salts I and II, succinic acid or anhydride are used. These compounds, alone or as a mixture, are typically present in the lubricating compositions for a 4-cycle engine in amounts of between 0.1 and 5% by weight.

The lubricating compositions according to the present invention may contain all types of antioxidant additives known to those skilled in the art, in amounts compatible with an overall level of sulphated ash of less than or equal to 0.5%, measured according to the ASTM D874 standard. phosphorus level less than or equal to 500 ppm measured according to ASTM D5185, and a sulfur content of less than or equal to 0.2% measured according to the ASTM D 5185 standard. Ashless antioxidants will be preferred. Detergents reduce the formation of deposits on the surface of metal parts by dissolving secondary oxidation and combustion products. The detergents used in the lubricant compositions according to the present invention are well known to those skilled in the art.

The detergents commonly used in the formulation of lubricating compositions are typically anionic compounds having a long lipophilic hydrocarbon chain and a hydrophilic head. The associated cation is typically a metal cation of an alkali or alkaline earth metal. The detergents are preferably chosen from alkali metal or alkaline earth metal salts of carboxylic acids, sulphonates, salicylates and naphthenates, as well as the salts of carboxylic acids, sulphonates, salicylates and naphthenates. phenates. The alkali and alkaline earth metals are preferably calcium, magnesium, sodium or barium. These metal salts may contain the metal in an approximately stoichiometric amount or in excess (in an amount greater than the stoichiometric amount). In the latter case, we are dealing with so-called overbased detergents. The excess metal providing the overbased detergent character is in the form of oil insoluble metal salts, for example carbonate, hydroxide, oxalate, acetate, glutamate, preferably carbonate. In the same overbased detergent, the metals of these insoluble salts may be the same as those of the oil-soluble detergents or may be different. They are preferably selected from calcium, magnesium, sodium or barium. The overbased detergents are thus in the form of micelles composed of insoluble metal salts maintained in suspension in the lubricating composition by the detergents in the form of oil-soluble metal salts. These micelles may contain one or more types of insoluble metal salts stabilized by one or more detergent types. Overbased detergents with a single type of detergent soluble metal salt will generally be named after the nature of the hydrophobic chain of the latter detergent. Thus, they will be called phenate, salycilate, sulphonate, naphthenate depending on whether this detergent is a salycilate, sulphonate or naphthenate, respectively. The overbased detergents will be said to be of mixed type if the micelles comprise several types of detergents, different from each other by the nature of their hydrophobic chain. The lubricant compositions according to the present invention may contain any type of detergent known to those skilled in the art, neutral or overbased, or highly overbased. The more or less overbased character of the detergents is characterized by the BN (base number), measured according to the ASTM D2896 standard, and expressed in mg of KOH R f3, e, eL 261nU '6I -V! ~ eco rv. JRR ^>. FI -I I Juc per gram. Neutral overbased detergents have a BN ranging from about 0 to about 80. Overbased detergents, on the other hand, have BN values typically of the order of 150 or more, or even 250 or 450 or more. The BN of the lubricant composition containing detergents is measured by ASTM D2896 and expressed as mg KOH per gram of lubricant. It is generally desirable to include in the engine lubricating compositions at least a portion of detergents in overbased form, so as to allow the neutralization of certain acidic impurities from the combustion and found in the oil.

However, these compounds contain metal salts which generate ash, and the formulation of low ash lubricants according to the present invention requires, while maintaining good detergency properties, to adjust the amount of detergents including overbased. Thus, the lubricant compositions according to the present invention can contain any type of detergents known to those skilled in the art, neutral or overbased, or strongly overbased, in amounts compatible with an overall sulfated ash level of less than or equal to 0, 5% measurement according to ASTM D2896. Preferably, the quantities of overbased detergents included in the lubricant compositions according to the invention are adjusted so that the BN of said compositions, measured according to the ASTM D2896 standard, is less than or equal to 8 mg of KOH per gram of lubricant, preferentially less than or equal to 6.5, preferably between 3 and 6. Viscosity improving polymers ensure a good cold resistance and a minimum viscosity at high temperature, especially for formulating multigrade oils. The introduction of these compounds into the lubricating compositions allows them to achieve viscosity index (VI) values giving them good fuel eco properties or fuel economy. Thus, the lubricant compositions according to the invention preferably have VI values, measured according to ASTM D2270. greater than or equal to 130, preferably greater than 1 50, preferably greater than 160. For example, among these compounds are polymeric esters, olefins copolymers (OCP), homopolymers or copolymers of styrene, R Cil e. (I22, C121i, J., et al., e.er-RI3OG-U.11Jo, butadiene or isoprene, polymethacrylates (PMA) .They are conventionally present at levels of 0 to 40%, preferably from 0.01 to 15% by weight, in the lubricating compositions for four-stroke engines, these compounds have the disadvantage of forming deposits, and their presence in the formulations, especially the fuel formulations. eco, leads the skilled person to increase the rate of detergent in lubricants, which is ash generator and does not achieve the specifications type ACEA Cl or ACEA C2, both low saps and fuel eco. the lubricants according to the present invention, the presence of heavy PAO (b) or PIB (b), as a total or partial substitution to the VI-improving polymers, and in combination with the hydroxylated esters (c), makes it possible to reduce the treatment rate detergent, and thus achieve a low ash rate. as well as low saps engine lubricants, with fuel-saving properties and non-degraded detergency performance.

The lubricant compositions according to the present invention may contain from about 0.0 to 10% by weight of VI improvers. Preferably, the compositions according to the invention contain at most 3% by weight of VI-improving polymers generating deposition, for example chosen from among the polymeric Esters, the Olefins Copolymers (OCP), the homopolymers or copolymers of styrene, butadiene or isoprene, polymethacrylates (PMA), preferably at most 2.5% by weight, or are free. Pour point depressant additives improve the cold behavior of oils by slowing the formation of paraffin crystals. They are, for example, alkyl polymethacrylates, polyacrylates, polyarylamides, polyalkylsphenols, polyalkylnaphthalenes, alkyl polystyrene, etc. Dispersants, for example succinimides, PIB (polyisobutene) succinimides, Mannich bases, ensure the suspension and evacuation of Insoluble solid contaminants consisting of the secondary oxidation products that form when the engine oil is in service.

To prepare the lubricating compositions according to the invention, the compounds (b), heavy PAO and / or PIB, the hydroxylated ester (s) (c) can be introduced as individual compounds. R tac.cr, _a_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, All or part of the additives may be part of a concentrate or package of additives which will be diluted in the base oil. or the base oil mixture (a). Thus, some additives can be introduced via the package, and others individually. In particular, the subject of the present invention is also such preparative processes, in particular a process where the additive package is diluted so as to represent from 10 to 30%, preferably from 15 to 20% by weight of the lubricating composition, and or the VI improving polymer represents from 0 to 3% of the lubricating composition.

The present invention also relates to packets of additives for four-stroke engine lubricant having a sulphated ash content of less than or equal to 0.5% measured according to ASTM D874, a phosphorus level is less than or equal to 500 ppm measured according to ASTM D5185, and a sulfur level is less than or equal to 0.2% measured according to ASTM D5185, which comprise: - at least one compound (b), heavy PAO and / or (P1B) - at least one hydroxylated ester (c) ) - optionally, anti-wear and extreme pressure additives, friction modifiers, detergents, antioxidants, overbased or non-overbased detergents, pour point depressants, dispersants, anti-foam additives, thickeners, Preferably, the additive packages according to the present invention comprise: from 0.5 to 30% by weight, preferably from 10 to 25% by weight, of at least one compound (b), PAO heavy and / or (P1B) - from 0.5 to 15% by weight, preferably from 2.75 to 8.75% by weight of at least one hydroxylated ester (c). Another object of the present invention relates to the use of lubricant compositions as described above as lubricant for four-stroke engine, diesel or gasoline, preferably for light-duty engine. Finally, the present invention relates to the use of hydroxylated esters (c) described above as friction modifiers for formulating lubricant compositions for four-stroke engine having a B-oltm ol '} n "C ~ ash content. Sodium sulfate: less than or equal to 0.5% measured according to ASTM D874, a phosphorus level of less than or equal to 500 ppm measured according to ASTM D5185, and a lower sulfur content. or 0.2% measured according to ASTM D5185. Of course, the present invention is not limited to the examples and the embodiment described and shown, but it is capable of many variants accessible to the human being. Example 1: Improvement of detergency properties by means of heavy PIB (b ') and PAO (b) Description of the compositions and preparation.

The compositions are described in Table 1. Composition A is a 5W30 grade reference composition comprising an OCP type enhancer polymer. In compositions B, C and D, a portion of OCP enhancer of VI with PIB or heavy PAO was substituted for reference A.

Table 1: Composition and properties ABCD Base oil Gr IV, mass% 15.00 14.98 14.48 15.13 Base oil Gr III, KV 100 "C = 5 Cst,% mass 22.84 22.81 22.05 23.04 Base oil Gr III KV 100 ° C = 4.3 Cst,% 40.00 39.95 38.62 40.36 mass Improving polymer of Vi OCP% mass 8.70 7.30 6.88 4.00 heavy PAO, KV 100 ° C = 1000 mm2 / s, 4.00 (Spectrasyn Ultra 1000 marketed by Exxon Mobil),% mass PIB (Indopol H2100, marketed by 1.50 Innovene-Ineos Oligomers),% mass GDP (Indopol H100, sold by 4.50 Innovene-Ineos Oligomers),% Phosphorus mass, ppm, ASTM D5185 500 500 500 500 Sulfur, ppm, ASTM D5185 1800 1800 1800 1800 Sulphated ash% mass 0.5 0.5 0.5 0 , 5 TBN (mg KOH / g) ASTM D2896 4.6 4.6 4.6 4.6 KV 100 mm2 / s, ASTM D445 12 11.94 1 1.97 R Bre, eis 26100 .20 In order to study the influence of polymer substitution OCP VI enhancer by heavy PAOs and PIB (respectively compounds b and b 'according to the invention), two laboratory tests were conducted on oils A, B, C, and D. MCT Microcoking test: The MCT (Micro Coking Test) is a test that assesses the tendency to form deposits on a hot surface (coking). The test conditions are as follows: MCT (according to GFC Lu-27-A-03 v.2) - 600 oil (+ 10 ppm defoamer) - time: 90 min - inclined plate of 1 to 2% with a bucket - temperature gradient from 230 to 280 ° C - Plate varnish quotation method 2 said division of squares (RO) ECBT test The ECBT test (Elf Coking Bench Test) is a holding test thermal on coking bench. It simulates a high-temperature engine piston that is sprayed with oil from a crankcase. The lubricant arrives on a very hot surface, deteriorates and gives rise to deposits. This test allows an approach of the nature of the deposits formed on the upper parts of the piston (crown, first groove and bottom of piston) as well as an estimate of the resistance of the oil to the weathering. Compared to MCT, this test is dynamic. A description of this essay can be found in Proceedings of the Marine Motorship Propulsion Conference 2000, Amsterdam, March 29-30, The Relevant Field Tests in Simulating Field Performance, by JP Roman.

ECBT test conditions Approx. 400g of oil Duration: 1 hour of scanning at different temperatures Temperatures: 290, 300 and 310 ° C Aluminum beaker No final sweep during cooling Rating of the swept area of the aluminum beaker (/ 100) The detergency properties are also evaluated by F9Q engine test, under the following conditions: - diesel engine 1.9 liter common rail - - duration 96 hours - 4000 rpm at full load - rating of piston fouling (varnish / carbon / overall) Table 2 gives the results of the detergency tests obtained for oils A, B, C and D. It can be seen that at the fixed detergent (fixed TBN) level, the detergency performances of the oils B, C, D where the PIB or the heavy PAO have been partially substituted for the OCP polymer are better than those of the reference A, which contains only OCP. Table 2: detergency tests. REF GDP GDP Heavy PAO ABCD MCT laboratory detergency tests (av merit / 10) Rating 2 8.0 8.5 8.5 8.6 ECBT, lh @ 290 ° C (quotation / 100) 34.3 50.4 38 36.6 ECBT, 1 h @ 300 ° C 19.5 32.4 23.9 22.5 ECBT, 1 h @ 310 ° C 16 22.5 22.9 16.9 Detergent Engine Test F9Q Carbon Rating / 10 8.2 8.4 Varnish Rating / 10 4.9 5.3 Overall Rating / 100 59.4 62.2 Example 2: Improved Fuel Properties Eco with MF 15 triethylcitrate (c) in the presence of PIB (b). Description of the Compositions and Preparation: Composition A 'is a reference composition with a very low level of ash, sulfur and phosphorus, 5W30, with a VI improving polymer different from that of reference A. The mass composition of oil A as well as its properties are given in Table 2. The composition B 'was prepared by adding 1% by weight of triethyl citrate to the composition A'. Eco fuel properties:

The fuel oil properties of the oils A 'and B' were measured by a Cameron Plint Frottement laboratory test. This laboratory test is correlated with the M 111 FE motor tests (CEC L54-T-96). The test bench consists of a plane cylinder tribometer immersed in the oil to be tested. A variable normal force is applied to the heated plane and the resulting frictional force is measured. Comparison of the results with those obtained for the reference oils of the MI 11 FE engine test (CEC L54-T-96) makes it possible to calculate the fuel economy achieved with the oil tested. The results reported in Table 3 below highlight the improvement of fuel eco properties induced by the addition of triethylcitrate. A 'B' Gr III, KV 100 ° C = 4 Cst,% mass 50.00 49.50 Gr III, KV 100 ° C = 6 Cst,% mass 20.00 19.80 Gr IV base oil, PAO KV 100 ° C = 10.00 9.90 4 Cst,% mass Improving polymer of VI (styrene-6, 50 6.43 Isoprene hydrogenated), ° / O mass Triethylcitrate (a), mass% -0.99 GDP (b ), mass% 2.00 1.98 Phosphorus, ppm 183 181 Sulfur,% mass 0.053 0.052 Sulphated ash,% mass 0.23 0.23 TBN (mg KOH / g) ASTM D2896 3.43 3.40 TBN (mg) KOH / g) ASTM D4739 2.53 2.50 KV 100 mm2 / s 11.89 1 1.89 Cameron Plint (% savings of 1.75 2.02 fuel) Table 3 Example 3: Improvement of fuel eco properties and detergency by the combination of heavy PAO (b) + triethylcitrate (c), and heavy PAO combination (b) + glycerol monoisostearate (c). Description of the compositions and preparation.

The composition E is one of a 5W30 grade reference composition comprising an OCP type enhancer polymer, and a composition of the invention. additive package comprising dispersants, detergents (Sulfonates and Calcium Phenates, weakly and strongly overbased), DTPZn, a friction modifier, amine and phenolic antioxidants, an anti foam additive, a pour point depressant. In compositions F, G and H, a part of the OCP-improving polymer of VI has been substituted, relative to reference E, by a heavy PAO with a kinematic viscosity at 100 ° C. of 1000 mm 2 / s, marketed by Exxon Mobil under SpectraSyn Ultra 1000. The compositions G and H are compositions according to the invention, in which the VI improving polymer is partially substituted by this same heavy PAO (compound (b)) and further comprising 1% by weight of a compound (c), respectively triethyl citrate and glycerol monoisostearate.

The compositions (in% by mass) and physicochemical properties of the compositions E, F, G, H are given in table 4. Fuel eco or fuel-saving properties: fuel-eco or fuel-saving properties, compositions E, F, G. H were evaluated by a motor test M11 FE and a Cameron Plint laboratory test. The detergency properties were evaluated by the ECBT test conducted at 280 ° C. The results are shown in Table 5. Fuel eco engine test conditions MI l 1 FE (CEC standard L54-T-96): 25 100KW 2L petrol engine Cycles that represent a taxi with a strong urban character: speed between 750 and 3070 rpm power between 0 and 49 KW oil temperature between 20 and 75 ° C 30 Fuel economy measured by comparison with a reference oil of grade 15W40 (RLI91). Test conditions Cameron Plint eco-fuel laboratory Friction: R Brc'ci 'well 2bl,? - OI.I3-, r ,, or, kr, er- PBUb-U3 1 Ioc This laboratory test is correlated with M1 engine tests 1FE (CEC standard L54-T-96). The test bench consists of a plane cylinder tribometer immersed in the oil to be tested.

 A variable normal force is applied to the heated plane and the resulting frictional force is measured. Comparison of the results with those obtained for the reference oils of the Mil 1 FE engine test (CEC L54-T-96) makes it possible to calculate the fuel economy achieved with the oil tested. Table 4: compositions (in mass%) and physico-chemical properties. E (Ref) FGH Base oil: Gr IV PAO, KV 100 ° C = 6 Cst 15,20% 15,20% 15,05% 15,05% Gr III, KV 100 ° C = 6 Cst 14,90% 14, 80% 14.65% 14.65% Gr III KV 100 ° C = 4 Cst 50.80% 50.80% 50.30% 50.30% Total Base oil 80.90% 80.80% 80.00 % 80.00% OCP Polymer 5.10% 2.20% 2.20% 2.20% Heavy PAO, KV at 100 ° C 1000 3.00% 3.00% 3.00% Spectrasyn 1000 Glycerol Monoisostearate 1.00% Triethylcitrate 1.00% Package of additives including: 13.80% 13.80% 13.80% 13.80% weakly and hard detergents 0.50% 0.50% 0.50% 0.50% overbased; amino and phenolic ashless antioxidants, dispersant succinimide anti-wear amine phosphate, of which DTPZn Pour point depressant 0.20% 0.20% 0.20% 0.20% Sulphated ash * 0.50% 0.50% 0.50 % 0.50% Phosphorus ** (ppm) 509 ppm 509 ppm 500 ppm 500 ppm Sulfur% *** 0.128% 0.128% 0.128% 0.128% TBN mgKOH / g ASTM D2896 5.95 5.95 5.95 5.95 KV at 100 ° C, in mm2 / s ASTM D445 9.96 9.94 10.04 9.952 KV at 40 ° C, in mm2 / s ASTM D445 57.65 57.81 57.99 56.64 VI 160 159 161 164 * ASTM D 874 measurement , ** measure ASTM D 5185, *** measure ASTM D 5185 R Rie •. and 26122-0-1'03-version Jrposer PH11h-tiI Jac Table 5: eco fuel and detergency properties. compositions E (ref) FGH - ECBT detergent 280 ° C 25.90 34.20 36.90 35.30 Fuel Economy FE Cameron Plint 1.97 1, 78 2.38 2.04 (% fuel savings) M 111 FE 1.90 2.19 2.50 (% fuel savings) Detergent results: The partial substitution of OCP with heavy PAO, in composition F, makes it possible to minimize the formation of deposit, thus to improve the properties in detergency compared to the reference E, constant treatment rate of detergent. The addition of hydroxylated esters is without influence and the good performances in detergency are preserved. Fuel eco results: The partial substitution of OCP type VI improving polymer with heavy PAO has a positive detergency effect but a negative effect on fuel eco properties (from 1.97 to 1.78 in Cameron Plint test ). The addition of hydroxyl ester in the compositions G and H makes it possible to compensate for the lowering of the fuel eco property and even to improve with respect to the reference. R P, e.eL 261.0 26122-0-12n3.wrxux, has eo-V130 ~ -0? I of

Claims (11)

claims A low ash lubricant composition for a four-stroke engine comprising: a) one or more base oils selected from Group I to V oils, preferably from Group III or IV oils of the API classification. b) at least one compound (b) chosen from the group of heavy PAOs with a kinematic viscosity at 100 ° C of between 75 and 3000 ° C, or in the group of polyisobutene (PIB) type polymeric compounds, or a mixture thereof and c) at least one ester of formula R (OH) n (COOR '(OH) p) n in which m is an integer from 0 to 8, preferably from 1 to 4, n is an integer of I to 8, preferably from 1 to 4 and p is an integer from 0 to 8, preferably from 1 to 4 and where the sum p + m is strictly greater than zero, R and R 'independently represent one of the other a linear or branched, saturated or unsaturated hydrocarbon group, optionally substituted with one or more aromatic groups, and comprising from 1 to 30 carbon atoms, and its borated derivatives; said composition having a sulphated ash content of less than or equal to 0.5% measured according to ASTM D874 standard, a phosphorus level of less than or equal to 500 ppm measured according to ASTM D5185 standard, and a sulfur content of less than 0.2% measured according to ASTM D5185. 2. Composition according to claim 1, in which the ester (c) contains at least one free OH hydroxyl group belonging to the R group, said OH group being located in the alpha, beta or gamma position relative to the carbon of the CO function. an ester function to which the group R is attached, and / or contains at least one free OH hydroxyl group belonging to the group R ', said OH group being located in the beta, gamma or delta position with respect to the oxygen of the COO group of an ester function on which the group R 'is attached. R 'Br, ei ^ _ ~ IPU 21.1 "-li'Cbi ~ rrsnm a -I I (-UNI back 28 3. Composition according to claim 1 or 2 wherein the R 'group of the ester (c) represents a group C1 to C10 preferably C2 to CE. 4. Composition according to claim 3 wherein p is strictly greater than zero and the group R of the ester (c) represents a C8 to C25 group preferably C12 to C18. 5. Composition according to claim 4 wherein at least one ester (c) is chosen from monoesters or diesters of glycerol, preferably chosen from glycerol monoleate, glycerol stearate or isostearate and their borated derivatives. 6. Composition according to claim 3 wherein n is an integer between 1 and 4 and the group R of the ester (c) represents a group C1 to C, preferably C 1 to C3. 7. Composition according to claim 6 wherein at least one ester (c) is selected from citrates, tartrates, malates, lactates, mandelates, glycolates, hydroxypropionates, hydroxyglutarates or their borated derivatives. 8. Composition according to one of claims 1 to 7 leading to a minimum fuel economy measured on test Mil 1FE of at least 2.5% and meeting specifications ACEA-C1 defined by the Association of European Automobile Manufacturers. 9. Composition according to one of claims 1 to 8 having a kinematic viscosity at 100 ° C measured by ASTM D445 between 5.6 and 16.3 Cst, preferably between 9.3 and 12.5 Cst. 30 10. Composition according to one of claims 1 to 9 having a grade 5W30 according to the classification SAEJ300. TFE \ 26I 22-071203-version to be deposited-PB06-031-correction RB.doc 25 11. Composition according to one of claims 1 to 10 having a viscosity index VI is greater than or equal to 130, preferably greater than 150. preferentially greater than 160. 1 2. Composition according to one of Claims 1 to I 1, in which the base oil or the mixture of base oils (a) represents at least 70% by weight of the said composition. 13. Composition according to one of claims 1 to 12 wherein the base oil or the mixture of base oils (a) comprises: - at least 60% by weight, based on the total weight of lubricant, a or more Group III base oils - not less than 10% by weight, based on the total weight of lubricant, of one or more Group IV base oils. 14. Composition according to one of claims 1 to 13 comprising a compound (b) selected from the group of heavy PAO, and a compound (b) selected from the group of polymeric compounds of PIB type. 15. Composition according to one of claims 1 to 14 comprising from 0.1 to 6%. preferably from 2 to 4% of at least one compound (b) and from 0.1 to 2.5%. preferably 0.5 to 1.5% of at least one compound (c). 16. Composition according to one of claims 1 to 15 comprising at least one anti-wear compound of the type of zinc dithiophosphates, optionally in combination with an amine phosphate. 17. Composition according to one of claims 1 to 16 comprising at least one anti-wear compound of the type of Zinc dithiophosphates in an amount of less than or equal to 1%, preferably less than or equal to 0.5%. 18. Composition according to one of claims 1 to 17 free of amine phosphate additive. R Br, e, 2e, 1011_61_LO: R03-, ee n.i depo-eo-PUR!, - 1 da19. Composition according to one of claims 1 to 18 free of Molybdenum friction modifier additive. 20. Composition according to one of claims 1 to 19 comprising at least one antioxidant compound, preferably without ash, preferably of phenolic or amine type. 21. Composition according to one of claims 1 to 20 comprising from 0.01 to 5% of one or more antioxidant additives. 22. Composition according to one of claims 1 to 21 having a BN, determined according to ASTM standard I) ù2896 less than or equal to 8 milligrams of potassium hydroxide per gram of lubricant, preferably less than or equal to 6.5 milligrams of potash per gram. lubricant 23. Composition according to one of claims 1 to 22 comprising between 0 and 3%, preferably between 0 and 2.5% of an improvement polymer of VI selected from polymeric esters, copolymer olefins (OCP), homopolymers or copolymers of styrene, butadiene or isoprene, polymethacrylates (PMA). 24. A method of manufacturing a lubricant composition according to claims I to 23 by dilution of a package of additives comprising at least one compound (b) and at least one compound (c), in a base oil or a mixture base oils (a), and optionally adding a VI-improving polymer. 25. The manufacturing method according to claim 24, wherein the additive package is diluted to represent from 10 to 30%, preferably from 15 to 20% by weight of the lubricating composition, and wherein the VI improving polymer represents from 0 to 20% by weight of the lubricating composition. at 3% by weight of the lubricating composition. 26. Package of additives for four-stroke engine lubricant with a sulfated ash content of not more than 0.5% as measured by ASTM D874, R Rre, and -6100261a-0 "I_li3.ru.mn drpo> Phosphorus levels less than or equal to 500 ppm measured according to ASTM D5185, and a sulfur content of less than 0.2%, measured according to ASTM D5185, characterized in that it comprises: least one compound (b), heavy PAO and / or (PIB), at least one hydroxyl ester (c), optionally anti-wear and extreme pressure additives, friction modifiers, detergents, antioxidants, detergents whether or not overbased, pour point depressants, dispersants, anti foam additives, thickeners, viscosity index improvers 27. Additive package according to claim 26 comprising: - 0.5 30% by weight, preferably 10 to 25% by weight, of at least one compound (b), heavy PAO and / or (PIB); from 0.5 to 15% by weight, preferably from 2.75 to 8.75% by weight of at least one hydroxylated ester (c). 28. Use of a composition according to any one of claims 1 to 23 as a four-cycle lubricant. 29. Use of at least one ester of formula R (OH) m (COOR '(OH) p) n in which m is an integer from 0 to 8, preferably from 1 to 4, n is an integer of 1 to 8, preferably 1 to 4 and p is an integer of 0 to 8, preferably 1 to 4 and where the sum p + m is strictly greater than zero, R and R 'independently represent one of the other a linear or branched, saturated or unsaturated hydrocarbon group, optionally substituted with one or more aromatic groups, and comprising from 1 to 30 carbon atoms, and its borated derivatives, as a friction modifier for the preparation of a composition Lubricant for a four-stroke engine having a sulphated ash level of less than or equal to 0.5% measured according to ASTM D874, a phosphorus level of less than or equal to 500 ppm measured according to ASTM D5185, and a level of sulfur of less than or equal to 0 , 2% measured according to ASTM D5185. R Bre, els'26100 2t, 12: 4), 1-2 (r, Set-and, R,