Lubrication of a rechargeable hybrid vehicle engine and a hybrid vehicle comprising a range extender

Abstract

The present invention relates to the use of a lubricant composition for lubricating a rechargeable hybrid vehicle engine or a hybrid vehicle engine comprising a range extender, said lubricant composition being of grade 0W-8 according to SAE J300 classification, comprising at least one base oil, from 1 ppm to 1000 ppm of at least one friction modifying additive and from 0.1 wt% to 10 wt% of at least one viscosity index improving polymer, said lubricant composition having a kinematic viscosity measured according to standard ASTM D445 at 40°C of less than or equal to 20 mm 2 / s; a kinematic viscosity measured according to standard ASTM D445 at 100°C of less than 5 mm 2 / s and a Noack volatility measured according to standard CEC-L-40-A-93 at 250°C of from 10% to 85%, preferably from 25% to 85%, more preferably from 60% to 85%.

Description

TECHNICAL FIELD

[0001] The present invention relates to the lubrication of hybrid vehicle engines of rechargeable hybrid vehicles and of hybrid vehicles comprising a range extender. BACKGROUND

[0002] Hybrid vehicles have two sources of energy: an internal combustion engine and an electric motor. In most hybrid vehicles, the internal combustion engine drives the wheels and is assisted by the electric motor. The battery provides the electric motor with the electricity it needs to operate, the battery in a traditional hybrid car is charged during braking and deceleration phases by a kinetic energy recovery system (KERS) integrated in the vehicle.

[0003] There are different technologies for hybrid vehicles. Among these hybrid technologies, mention can be made in particular of:

[0004] - micro-hybrid vehicles (also known as mild hybrids), these vehicles are equipped with a "stop & start" system to recover the energy produced by braking to charge the battery, which can provide instantaneous assistance to the internal combustion engine;

[0005] - mild hybrid vehicles, comprising electric power assistance during acceleration;

[0006] - full hybrid vehicles are vehicles with complete hybridization. At low speed, when the battery is charged, the electric motor takes over for starting and power. At high speed, or when the battery is discharged, when additional power is needed (for example for acceleration), the internal combustion engine takes over and the two power sources operate together. It is thus possible to travel a few kilometers with the internal combustion engine turned off.

[0007] Other complementary technologies have also been developed recently: rechargeable hybrid vehicles and hybrid vehicles comprising a range extender. Rechargeable hybrid cars (also known as plug-in vehicles) comprise an internal combustion engine and an electric motor, the battery of which can be charged via the electricity grid, these vehicles can thus travel in 100% electric mode over a distance of several tens of kilometers, for example 50 kilometers. In hybrid vehicles comprising a range extender, only the electric motor drives the wheels. This electric motor is powered by a battery for several tens of kilometers of travel. When the battery reaches a certain charge threshold (for example around 30%), the internal combustion engine starts and drives an electric current generator, thus producing the necessary electricity to charge the battery and maintain the operation of the electric motor.

[0008] Compared to the engines of other types of hybrid vehicles, the internal combustion engine is less frequently used in these two types of hybrid vehicles, it thus operates at lower temperatures (around 40°C or even below 40°C). However, at low temperature, conventional lubricant compositions are more viscous and the additives are not as active as in the conventional applications at higher temperatures. Current lubricants have been optimized to obtain the benefits in terms of fuel consumption when the engine is hot.

[0009] Therefore, there is a need to provide a specific lubricant composition which allows lubricating said engine system, in particular at lower temperatures. SUMMARY

[0010] An object of the present application is to provide a lubricant composition which can lubricate a rechargeable hybrid vehicle engine or an engine comprising a range extender.

[0011] Another object of the present application is to provide said lubricant composition which can be used at low operating temperatures, in particular below 40°C.

[0012] The present application meets these objectives, it relates to the use of a lubricant composition for lubricating a rechargeable hybrid vehicle engine or a hybrid vehicle engine comprising a range extender, said lubricant composition being of grade 0W-8 according to SAE J300 classification, comprising at least one base oil, 0.01 to 10 wt% of at least one friction modifying additive and 0.1 to 10 wt% of at least one viscosity index (VI) improver, said lubricant composition having a kinematic viscosity measured at 40°C (KV40) of less than or equal to 20 mm 2 / s; a kinematic viscosity measured at 100°C (KV100) of less than or equal to 5 mm 2 / s and a Noack volatility measured at 250°C of 10 to 85%, preferably 25 to 85%, more preferably 60 to 85%.

[0013] Preferably, said base oil (or mixture of base oils if more than one base oil) has a KV100 value of 1 to 4 mm 2 / s, preferably 2 to 3.5 mm 2 / s. DETAILED DESCRIPTION

[0014] The KV100 viscosity of the base oil is also referred to as Base Oil Viscosity - BOV.

[0015] If a mixture of base oils, the KV100 (vM) of the mixture of base oils is calculated as follows, for example for a mixture of 2 base oils the calculation method is:

[0016]

[0017] Wherein:

[0018] x% of base oil 1 BO1

[0019] x% of base oil 2 BO2 ​​

[0020] ν BO1 , viscosity of mixture 1

[0021] ν BO2 , viscosity of mixture 2

[0022] ν M , viscosity of mixture

[0023] For a mixture of n base oils, the same equation can be used and extrapolated.

[0024] Preferably, the composition of the application comprises at least one dispersant. Said dispersant ensures that the insoluble solid contaminants of the secondary oxidation products formed are maintained in suspension and drained when the lubricant composition is used. This dispersant can be chosen from Mannich bases, succinimides and their derivatives, such as derivatives of polyisobutylene succinic anhydride, polyolefin amide enamine polyols.

[0025] Preferably, the composition of the application comprises from 0.5% to 4.5% by weight of dispersant, preferably from 1% to 2.5% by weight of dispersant, relative to the total weight of the lubricant composition.

[0026] KV40 and KV100 are measured according to the standard ASTM D445. Preferably, the KV40 of the composition of the application is less than or equal to 20 mm 2 / s, preferably 10 mm 2 / s to 20 mm 2 / s, preferably 11 mm 2 / s to 15 mm 2 / s. Preferably, the KV100 of the composition of the application is from 1 mm 2 / s to 5 mm 2 / s, preferably 2.5 mm 2 / s to 5 mm 2 / s.

[0027] The Noack volatility at 250°C is measured according to the CEC L-40-A-93 method. Preferably, the Noack volatility at 250°C of the lubricant composition of the application is from 10% to 85%, preferably from 25% to 85%, more preferably from 60% to 85%.

[0028] Preferably, the lubricant composition comprises from 50% to 95% by weight of base oil, preferably from 70% to 90% by weight of base oil, relative to the total weight of the lubricant composition.

[0029] Preferably, the lubricating composition can also comprise at least one viscosity index (VI) improving additive. Viscosity index improvers, in particular viscosity index improving polymers, can guarantee good cold start performance and minimum viscosity at high temperature. As examples of viscosity index improving polymers, one can mention polymeric esters, hydrogenated or non-hydrogenated homopolymers or copolymers of styrene, butadiene and isoprene, homopolymers or copolymers of olefins such as ethylene or propylene, polyacrylates and polymethacrylates (PMA), preferably homopolymers, polymethacrylates or copolymers of olefins such as ethylene or propylene.

[0030] In particular, the lubricant composition of the application can comprise from 1 to 15% by weight of viscosity index improving additive, preferably from 5 to 10% by weight, relative to the total weight of the lubricant composition.

[0031] Preferably, the lubricant composition of the application comprises at least one friction modifying additive. Friction modifying additives, which can limit friction by forming a monolayer adsorbed on the surface of the metal surface in contact, can be chosen from compounds providing metal elements and ashless compounds. Among the compounds providing metal elements, one can mention complexes of transition metals such as Mo, Sb, Sn, Fe, Cu, Zn, the ligand of which can be a hydrocarbon compound comprising oxygen, nitrogen, sulfur or phosphorus atoms. Ashless friction modifier additives are generally of organic origin and can be chosen from esters of fatty acids and polyols different from the monoester required in the application, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, borate ester fatty epoxides, fatty amines or fatty acid glycerides. In the present application, a fatty compound comprises at least one hydrocarbon radical having from 10 to 24 carbon atoms. In particular, the molybdenum-based compounds can be chosen from molybdenum dithiocarbamates (Mo-DTC), molybdenum dithiophosphates (Mo-DTP) and mixtures thereof. Advantageously, the lubricant composition of the application can comprise from 0.01 to 10% by weight of friction modifying additive, or from 0.01 to 5% by weight, more preferably from 0.01 to 2% by weight, further preferably from 0.1 to 1.5% by weight, or from 0.1 to 2% by weight, relative to the total weight of the lubricant composition.

[0032] The molybdenum (Mo) in the lubricant composition of the application is provided by an organomolybdenum compound, in particular a compound chosen from molybdenum dithiocarbamate derivatives (MoDTC), molybdenum dithiophosphate derivatives (MoDTP) or sulfur-free molybdenum complexes, preferably a molybdenum dithiocarbamate derivative (MoDTC).

[0033] The molybdenum dithiocarbamate compounds (MoDTC compounds) are complexes formed from a metal core linked to one or more ligands independently selected from dithiocarbamate alkyl ester groups. The MoDTC compounds used in the composition of the application can comprise from 0.01 wt% to 5 wt%, preferably from 0.1 wt% to 1.5 wt% of molybdenum relative to the total weight of the MoDTC compound.

[0034] Preferably, the composition of the application comprises a molybdenum-based friction modifying additive and preferably comprises (active content) from 1 ppm to 1000 ppm of Mo, preferably from 400 ppm to 600 ppm of Mo, relative to the weight of the lubricant composition.

[0035] In the present application, a chargeable hybrid vehicle (also called plug-in hybrid) is a vehicle comprising an internal combustion engine and an electric motor, the battery of which can be recharged on the electrical network, thus the vehicle can travel in 100% electric mode for several tens of kilometers, for example 50 kilometers.

[0036] In the present application, a hybrid vehicle comprising a range extender is a hybrid vehicle in which only the electric motor drives the wheels. This electric motor is powered by the battery for several tens of kilometers. When the battery reaches a certain charge threshold (for example around 30%), the internal combustion engine starts and drives the electric current generator, allowing the necessary power production to charge the battery and maintain the operation of the electric motor.

[0037] In a particularly advantageous manner, for chargeable hybrid vehicles or those comprising a range extender, the use of the lubricant composition of the application makes it possible to obtain a reduction in consumption that is higher than in other hybrid motorization systems.

[0038] The use of the composition of the application also provides greater fuel economy (FE) gains compared to conventional lubricants, as demonstrated on range extenders and plug-in hybrid vehicles.

[0039] The base oil used in the lubricant composition of the application can be a mineral or synthetic source oil (Table A) belonging to Group I to V (or equivalent in ATIEL classification) defined by the API classification, optionally re- generated, or a mixture thereof.

[0040] [Table 1]

[0041]

[0042] The mineral base oils of the application include all types of base oils obtained by atmospheric distillation and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrotreatment, hydrocracking, hydroisomerization and hydrofining, for example.

[0043] Mixtures of optionally regenerated synthetic and mineral oils can also be used.

[0044] There is generally no restriction on the use of different lubricant base oils for the preparation of the lubricant composition of the application, provided that they have properties suitable for use in a vehicle engine or transmission, in particular viscosity, viscosity index, sulphur content, oxidation resistance.

[0045] The base oil of the lubricant composition of the application can also be chosen from synthetic oils, such as certain esters of carboxylic acids with alcohols, and from polyalphaolefins. The polyalphaolefins used as base oil are obtained, for example, from monomers having 4 to 32 carbon atoms, such as octene or decene, and have a viscosity at 100°C of 1.5 to 15 mm 2 -1 According to standard ASTM D5296, their average molar mass is generally 250 to 3000.

[0046] The lubricant composition of the application can comprise at least 50% by weight of base oil, relative to the total weight of the composition. More advantageously, the lubricant composition of the application comprises at least 60% by weight, even at least 70% by weight of base oil, relative to the total weight of the composition. More particularly advantageously, the lubricant composition of the application comprises 75% to 95% by weight of base oil, relative to the total weight of the composition.

[0047] The application also provides a lubricant composition for a vehicle engine, comprising at least one lubricant composition of the application, at least one base oil and at least one additive.

[0048] Many additives can be used in the lubricant composition of the application.

[0049] The preferred additives of the lubricant composition of the application are chosen from detergent additives, antiwear additives, extreme pressure additives, pour point activators, antifoams, thickeners and mixtures thereof.

[0050] Preferably, the lubricant composition of the application comprises at least one antiwear additive, at least one extreme pressure additive or mixtures thereof.

[0051] Antiwear additives and extreme pressure additives prevent surface friction by forming a protective film that is adsorbed on these surfaces.

[0052] ​Anti-wear additives are numerous. Preferably, for the lubricant composition of the application, the anti-wear additive is selected from phosphosulfurized additives, such as alkyl thiophosphoric acid metal salts, in particular zinc alkyl thiophosphates, more particularly zinc dialkyldithiophosphates or ZnDTP. Preferred compounds have the formula Zn((SP(S)(OR)(OR'))2, wherein R and R' are identical or different, each independently an alkyl group, preferably an alkyl group having 1 to 18 carbon atoms.

[0053] Phosphorus amine is also an anti-wear additive that can be used in the lubricant composition of the application. However, these additives provide phosphorus that can be toxic to the catalytic system of a motor vehicle, as these additives generate ash. These effects can be minimized by replacing part of the amine phosphates by additives that do not provide phosphorus, such as polysulfides, in particular sulfur-containing olefins.

[0054] Advantageously, the lubricant composition of the application can comprise from 0.01 wt% to 6 wt%, preferably from 0.05 wt% to 4 wt%, more preferably from 0.1 wt% to 2 wt% of anti-wear additives and extreme pressure additives, relative to the total weight of the lubricant composition.

[0055] Advantageously, the lubricating composition of the application can comprise at least one antioxidant additive.

[0056] Antioxidant additives generally can delay the degradation of the lubricant composition when in use. This degradation can be through the presence of sludge or an increase in the viscosity of the lubricant composition, in particular translated into the formation of deposits.

[0057] Antioxidant additives are in particular used as free radical inhibitors or hydroperoxide decomposers. Among the antioxidant additives used most often, mention can be made of phenolic antioxidant additives, amine antioxidant additives, sulfur-phosphorus antioxidant additives. Some of these antioxidants, such as sulfur-phosphorus antioxidants, can generate ash. Phenolic antioxidant additives can be ashless, or can be in the form of neutral or basic metal salts. The antioxidant additive can in particular be selected from sterically hindered phenols, sterically hindered phenol esters, sterically hindered phenols comprising a thioether bridge, diphenylamines, N,N'-dialkyl-aryl-diamines and mixtures thereof. 12 alkyl-substituted diphenylamines, N,N'-dialkyl-aryl-diamines and mixtures thereof.

[0058] Preferably, in the present application, the sterically hindered phenol is selected from compounds comprising a phenolic group, wherein at least one carbon atom in the vicinity of the carbon atom bearing the alcohol function is alkyl-substituted, preferably C1-C6 alkyl, more preferably C4 alkyl, preferably tert-butyl. 10 alkyl-substituted, preferably C1-C6 alkyl, more preferably C4 alkyl, preferably tert-butyl.

[0059] Amino compounds are another class of antioxidant additives that can be used, possibly in combination with the phenolic antioxidant additives. Examples of amine compounds are aromatic amines, such as aromatic amines of the formula NR a R b R c wherein Ra is an optionally substituted aliphatic group or aromatic group, R b is an optionally substituted aromatic group, R c is a hydrogen atom, an alkyl group, an aryl group or a group of the formula R d S(O) z R e wherein R d is an alkylene or alkenylene group, R e is an alkyl, alkenyl or aryl group, and z is 0, 1 or 2.

[0060] Sulphurised alkyl phenols or their alkali or alkaline earth metal salts can also be used as antioxidant additives.

[0061] Other classes of antioxidant additives are copper compounds, such as copper thio- or dithiophosphates, copper salts and carboxylates, copper dithiocarbamates, sulfonates, phenates, acetylacetonate compounds. Salts of copper I and II, of succinic acid or anhydride can also be used.

[0062] The lubricant composition of the application can contain any type of antioxidant known to the person skilled in the art.

[0063] Advantageously, the lubricant composition comprises at least one ashless antioxidant additive.

[0064] Likewise advantageously, the lubricant composition of the application comprises from 0.1 wt% to 2 wt% of at least one antioxidant additive, relative to the total weight of the composition.

[0065] The lubricant composition of the application can also comprise at least one detergent additive.

[0066] Detergent additives generally reduce the formation of deposits on the surface of metal parts by dissolving oxidation and combustion by-products.

[0067] Detergent additives that can be used in the lubricant composition according to the application are generally known to the skilled person. The detergent additive can be an anionic compound comprising a long lipophilic hydrocarbon chain and a hydrophobic head. The associated cation can be a metal cation of an alkali metal or an alkaline earth metal.

[0068] The detergent additive is preferably chosen from the group consisting of alkali metal or alkaline earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates and phenates. The alkali metal and alkaline earth metal are preferably calcium, magnesium, sodium or barium.

[0069] These metal salts generally comprise stoichiometric or excess metal, i.e. an amount greater than stoichiometric. They are high alkaline detergent additives; the excess metal which imparts the high alkaline nature to the detergent additive is generally present in the form of an oil insoluble metal salt, such as a carbonate, hydroxide, oxalate, acetate, glutamate, preferably a carbonate.

[0070] Advantageously, the lubricant composition of the application can comprise from 0.5 to 8% by weight, or from 2 to 4% by weight of detergent additive, relative to the total weight of the lubricant composition.

[0071] Likewise advantageously, the lubricant composition of the application can comprise at least one pour point depressant additive.

[0072] By slowing the formation of paraffin crystals, the pour point depressant additive generally improves the cold start performance of the lubricant composition of the application.

[0073] Examples of pour point depressant additives can be mentioned polymethylalkylacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, alkylated polystyrenes.

[0074] The present application relates to a method of lubricating a rechargeable hybrid vehicle engine or a hybrid vehicle engine comprising a range extender, the method comprising contacting at least one mechanical part of the engine with a lubricant composition of grade 0W-8 according to SAE J300 classification, said lubricant composition comprising at least one base oil, at least one friction modifying additive and from 0.1 to 10% by weight of at least one viscosity index improving polymer, said lubricant composition having a KV40 less than 20 mm 2 / s, a KV100 less than 5 mm 2 / s, and a Noack volatility at 250°C of from 10 to 85%, preferably from 25 to 85%, more preferably from 60 to 85%.

[0075] Said lubricant composition is preferably as defined above

[0076] The present application also relates to a method of reducing the fuel consumption of a rechargeable hybrid vehicle engine or a hybrid vehicle engine comprising a range extender, the method comprising contacting at least one mechanical part of the engine with a lubricant composition of grade 0W-8 according to SAE J300 classification, said lubricant composition comprising at least one base oil, at least one friction modifying additive and from 0.1 to 10% by weight of at least one viscosity index improving polymer, said lubricant composition having a KV40 less than or equal to 20 mm 2 / s, a KV100 less than 5 mm 2at 250°C, the Noack volatility is between 10 and 85%, preferably between 25 and 85%, more preferably between 60 and 85%.

[0077] The composition is preferably as described above.

[0078] The application will be described below with the help of the following non-limiting examples. BRIEF DESCRIPTION OF DRAWINGS

[0079] Figure 1 The trends of the engine speed (right-hand axis, in rpm) and of the lubricating oil temperature (left-hand axis, in °C) during the WLTC test are shown.

[0080] EXAMPLE

[0081] Example 1 : Compositions of the invention and control compositions

[0082] The following lubricant compositions (CC: control composition; CL: composition of the application) were prepared.

[0083] [Table 2]

[0084]

[0085] Example 2: Savings in WLTC cycle consumption

[0086] The compositions in Example 1 were subjected to a hybrid application simulation under WLTC test (or WLTP - Worldwide Harmonized Light-duty Vehicles Test Procedure) to determine the savings in fuel consumption.

[0087] In this respect, the friction tests (FMEP = Friction Mean Effective Pressure) of the different lubricant compositions described in Example 1 were carried out on a test bed comprising a Nissan X-Trail MR20 engine driven by a generator to produce a speed of 550 rpm to 2800 rpm at a power of 108 kW at 5600 rpm, while a torque sensor can measure the friction torque generated by the movement of the engine parts. For each engine speed and for each mean torque at each temperature, the friction torque induced by the lubricant composition to be tested was compared with the friction torque induced by a reference lubricant composition (SAE 0W16) evaluated before and after each lubricant composition to be tested.

[0088] The higher the value of the reduction in friction torque, the more the lubricant composition can reduce the friction occurring in the engine.

[0089] The conditions of this test are as follows.

[0090] The test was carried out in the following order:

[0091] - rinsing the engine with detergent additives of lubricating oil, including one rinse, followed by two rinses with a reference lubricant composition of grade 0W-12, said reference lubricant composition comprising, relative to the total weight of base oil, 81.7 wt% of base oil, 17.8 wt% of usual additives (4.4% of viscosity index improver, 0.5% of antioxidant, 0.20% of pour point depressant and 12.7% of additive package) and 0.05 wt% of molybdenum dithiocarbamate (MoDTC);

[0092] - measuring the friction torque on the engine using the reference lubricant composition at two different temperatures shown below;

[0093] - rinsing the engine with detergent additives of lubricating oil, including one rinse, followed by two rinses with the lubricant composition to be evaluated;

[0094] - measuring the friction torque on the engine using the lubricant composition to be evaluated at two different temperatures;

[0095] - rinsing the engine with detergent additives of lubricating oil, including one rinse, followed by two rinses with the reference lubricant composition; and

[0096] - measuring the friction torque on the engine using the reference lubricant composition at two different temperatures shown below.

[0097] The speed range, speed variation and temperature were chosen in agreement with Nissan to represent the WLTC cycle.

[0098] The following specifications are:

[0099] - water temperature from the engine: 30°C / 50°C / 80°C + / - 0.5°C

[0100] - gasoline temperature ramp: 50°C / 80°C + / - 0.5°C

[0101] The results are given in Table 3 below and show the friction reduction of the composition in Example 1, in %, compared to Nissan Strong Save X 0W-16 oil, used as reference oil and control point for this part of the test, expressed as a function of engine speed and temperature.

[0102] [Table 3]

[0103]

[0104]

[0105] At the same time, a WLTC test was also performed on a vehicle with the same engine as the one mentioned in the previous step, to explicitly measure the fuel consumption and the actual measurement of the oil temperature throughout the cycle. According to the graph in Figure 1 the driving test was performed using a single reference lubricant, the same as the one used to establish the reference for the PMF test described above: Nissan Strong Save X 0W16 oil.

[0106] Therefore, the oil temperature and fuel consumption levels were measured on a Nissan X-Trail MR20 engine under WLTC cycles. Different power levels of electrical assistance were considered from 1 kW to 35 kW, representing a wide variety of hybrid types.

[0107] In this regard, a power of 1 kW to 2 kW represents electrical assistance of light hybrid types (micro and mild hybrid, respectively).

[0108] A power of 5 kW represents electrical assistance of full hybrid vehicles.

[0109] Finally, a power of 18 kW or 33 kW represents electrical assistance of the most advanced hybrid types (range extender and rechargeable (plug-in) hybrid, respectively).

[0110] Next, simulations of oil temperature and fuel consumption were performed for different types of hybrid vehicles as a function of the hybrid type described above and taking into account the engine shutdown when the power demand is below the level of electrical power available. These simulations were performed for the lubricant composition described in, for example, Example 1, and the results in terms of friction coefficient are known.

[0111] Finally, the simulated oil temperature was predicted (by linear interpolation of the results of friction) and the advantage or loss obtained (result of the friction coefficient obtained) was applied to the fuel consumption. Fuel consumption was only considered when the engine was running.

[0112] Each of the along-line simulations of oil temperature was converted by linear interpolation of the results of FTT FE [= f(T °C) & engine speed (rpm)] and the advantage / penalty ratio was applied to the corresponding fuel consumption point. The fuel consumption trajectory was then integrated to obtain a comparable and comparable overall fuel economy level.

[0113] The following results were obtained and show the fuel savings when lubricating the engine with the composition in Example 1.

[0114] [Table 4]

[0115]

[0116] The results in Table 4 show that the compositions of the present application enable a significant fuel savings for chargeable hybrid systems (plug-in hybrids) and hybrid systems including a range extender. In contrast, these same compositions of the present application do not enable a significant fuel reduction in other types of hybrid transmissions. These results indicate that the compositions of the present application are particularly effective for chargeable hybrid engines and for hybrid engines including a range extender.

[0117] Furthermore, extrapolating from the above, the average temperature of the lubricating oil is 70°C higher than for a non-hybrid vehicle engine, 60°C higher than for a micro-hybrid vehicle, 55°C higher than for a mild hybrid vehicle, 50°C higher than for a full hybrid vehicle, and 40°C lower than for a hybrid vehicle including a range extender and a chargeable hybrid vehicle.

Claims

1. Use of a lubricant composition for lubricating a chargeable hybrid vehicle engine or a hybrid vehicle engine comprising a range extender, said lubricant composition being of grade 0W-8 according to SAE J300 classification, comprising at least one base oil, at least one friction modifying additive and 0.1 to 10 wt% of at least one viscosity index improving polymer, said lubricant composition having a kinematic viscosity measured according to standard ASTM D445 at 40°C of less than or equal to 20 mm2 / s; a kinematic viscosity measured according to standard ASTM D445 at 100°C of less than 5 mm2 / s and a Noack volatility measured according to standard CEC-L-40-A-93 at 250°C of 25% to 85%. 2 2 / s; a kinematic viscosity measured according to standard ASTM D445 at 100°C of less than 5 mm2 / s and a Noack volatility measured according to standard CEC-L-40-A-93 at 250°C of 25% to 85%.​ 2. Use according to claim 1, wherein, The base oil has a kinematic viscosity measured according to standard ASTM D445 at 100°C of 1-4 mm2 / s. 2 / s.

3. Use according to claim 1 or 2, wherein, The lubricant composition comprises 0.5 to 4.0% by weight of the dispersant, relative to the total weight of the lubricant composition.

4. The use according to claim 1, wherein, Kinematic viscosity of 10 to 20 mm2 / s measured at 40°C according to standard ASTM D445 2 / s.

5. The use according to claim 1, wherein, The kinematic viscosity of the lubricant composition is 1 to 5 mm 2 / s at 100 °C measured according to standard ASTM D445.

6. The use according to claim 1, wherein, The lubricant composition comprises 50 to 95% by weight of the base oil, relative to the total weight of the lubricant composition.

7. The use according to claim 1, wherein, The lubricant composition comprises 0.01 to 10% by weight of the friction modifier additive, relative to the total weight of the lubricant composition.

8. The use according to claim 1, wherein, The lubricant composition comprises 0.01 to 5% by weight of the friction modifier additive, relative to the total weight of the lubricant composition.

9. The use according to claim 1, wherein, The friction modifier additive is molybdenum-based.

10. A method for lubricating a hybrid vehicle engine, chargeable or comprising a range extender, said method comprising contacting at least one mechanical part of the engine with a lubricant composition graded 0W-8 according to SAE J300, said lubricant composition comprising at least one base oil, at least one friction modifying additive and 0.1 to 10 wt% of at least one viscosity index improving polymer, said lubricant composition having a kinematic viscosity measured according to standard ASTM D445 at 40°C of less than 15 mm 2 / s; a kinematic viscosity measured according to standard ASTM D445 at 100°C of less than 5 mm 2 / s and a Noack volatility measured according to standard CEC-L-40-A-93 at 250°C of 25% to 85%.

11. A method for reducing fuel consumption of a chargeable hybrid vehicle or a hybrid vehicle comprising a range extender, the method comprising contacting at least one mechanical component of an engine with a lubricant composition according to SAE J300 classification of grade 0W-8, the lubricant composition comprising at least one base oil, at least one friction modifying additive and 0.1 to 10 wt.% of at least one viscosity index improving polymer, the lubricant composition having a kinematic viscosity measured according to standard ASTM D445 at 40°C of less than 15 mm 2 / s; a kinematic viscosity measured according to standard ASTM D445 at 100°C of less than 5 mm 2 / s and a Noack volatility measured according to standard CEC-L-40-A-93 at 250°C of 25% to 85%.

Images