JP6302371B2 - Low viscosity lubricant composition - Google Patents

Description

  The present invention relates to lubricating compositions, and in particular, to crankcase lubricating compositions having a lower viscosity than Group III base oils.

  Lubricants have applications in internal combustion engines, gearboxes and other mechanical devices to promote smoother functions, reduce wear on metal-to-metal contacts between moving parts, and remove heat. Lubricating oils (engine oils) used in internal combustion engines must exhibit a high level of performance, especially under the high performance, high power and severe operating conditions of internal combustion engines. The fuel efficiency performance required for lubricating oils has been increasing in recent years, and as a result, various high viscosity index base oils or friction modifiers have been utilized. Various additives such as antiwear agents, overbased detergents, ashless dispersants, viscosity modifiers and antioxidants can be added to conventional engine oils to meet such performance requirements.

  For many applications, the lubricant composition requires the presence of a polymeric viscosity modifier additive to obtain the desired viscosity characteristics over a wide range of shear and / or temperature. These additives are usually highly viscous liquids or solids at room temperature. In order to be able to achieve a homogeneous distribution, to avoid handling solids and to control the amount of additive added to the lubricant composition, thus ensuring consistent quality These additives are usually added as additive concentrates.

  Fischer-Tropsch derived base oils (hereinafter gas-to-liquid or “GTL” base oils) are increasingly finding use in lubricating compositions such as engine oils, transmission fluids and industrial lubricants. These compositions are based on traditional mineral base oils, including improved oxidation properties, improved engine cleanliness, improved wear protection, improved exhaust and improved aftertreatment device compatibility. Enjoy the benefits of various performances.

  Mineral base oils have typically been used in the preparation of lubricating compositions. However, blending engine oil (including motor oil for passenger cars and diesel engine oil for large vehicles) using mineral base oil that matches the thinner grade of SAE J300 specifications (revised April 2013) such as SAE 0W-X. There is a problem with doing. Furthermore, mineral-based engine oils can suffer from one or more of poor fuel economy, poor wear performance and low Noack volatility when used with relatively thin engine oils.

  As the demand for further improving lubrication performance increases, there is a need to develop lower viscosity lubricating compositions that demonstrate improved properties.

(Summary of the Invention)
One or more of the above or other objects can be obtained with a lubricating oil composition comprising a blend of (a) a GTL3 base oil and (b) a base oil comprising a GTL4 base oil. In certain embodiments, the blend of base oils can include up to about 12% by weight of GTL3 base oil. Alternatively, the base oil blend may comprise between 1 and 12% by weight of GTL3 base oil. In other embodiments, the base oil blend may comprise at least 88% by weight of GTL4 base oil. In other embodiments, the blend of base oils can comprise between 88 and 99% by weight of GTL4 base oil.

(Detailed description of the invention)
In certain embodiments, one or more of the objectives can be achieved using a lubricating composition having a Fischer-Tropsch derived base oil, wherein the first Fischer-Tropsch derived base oil is 2.5 at 100 ° C. The second Fischer-Tropsch derived base oil has a kinematic viscosity between 3.7 and 4.3 cSt at 100 ° C. and a kinematic viscosity between 30 and 3.0 cSt and a Noack volatility higher than 30% by weight. It has a Noack volatility of less than 15% by weight.

  In certain embodiments, one or more of the above or other purposes may be obtained by a lubricating composition comprising a blend of base oils, the blend being between 2.5 and 3.5 cSt at 100 ° C. A first Fischer-Tropsch derived base oil having a kinematic viscosity up to about 12% by weight and a second Fischer-Tropsch derived base oil having a kinematic viscosity at 100 ° C. between 3.5 and 4.5 cSt at least 88 This lubricating composition has a NOACK volatility of less than 15% by weight.

  One or more of the objects of the present invention can be achieved by a lubricating composition comprising a blend of Fischer-Tropsch derived base oils. More specifically, the Fischer-Tropsch derived base oil blend includes a GTL3 base oil and a GTL4 base oil. It has been surprisingly found that combining GTL3 and GTL4 base oils provides a low viscosity lubricating composition for use in high fuel efficiency engines. In certain embodiments, the lubricating composition can include a GTL8 base oil that can be added for volatility purposes.

  The term “Fischer-Tropsch derived” refers to a base oil that is a synthetic product of or derived from a Fischer-Tropsch process. A Fischer-Tropsch derived base oil may be referred to as a GTL (gas to liquid) base oil. Fischer-Tropsch derived base oils that can be conveniently used as base oils in the lubricating compositions of the present invention include, for example, EP0776959; EP0668342; WO1997 / 21788; WO2000 / 15736; WO2000 / 14188; WO2000 / 14187; WO2000 / 14187; WO2000 / 14179; WO2000 / 08115; WO1999 / 41332; EP1029029; WO2001 / 18156; and WO2001 / 57166.

  Suitable base oils for use in the lubricating oil compositions of the present invention include Group I-III mineral base oils (preferably Group III), Group IV poly-alpha olefins (PAO) and mixtures thereof.

  As used herein, "Group I", "Group II", "Group III" and "Group IV" base oils in the present invention referred to in one or more of the above or other purposes are the American Petroleum Institute. (API) can be obtained by a lubricating oil composition comprising a lubricating base oil in accordance with the definitions of classes I, II, III and IV (these API classifications are API Publication 1509, 15th edition, Appendix E, Defined in April 2002). Fischer-Tropsch derived base oils are known in the art.

  Synthetic oils that can be included in the formulations of the present invention include olefin oligomers (poly alpha olefin base oils; including PAO), dibasic acid esters, polyol esters, polyalkylene glycols (PAGs), alkyl naphthalene and dewaxed. Hydrocarbon oils such as waxy isomerates that have been made can be included. A synthetic hydrocarbon base oil sold under the name “Shell XHVI” ™ from Shell Group may be conveniently used in the present invention.

  Fischer-Tropsch derived base oil is a highly paraffinic API Group III base oil (API Base Oil Interchangeability Guidelines) that exhibits very good cold flow properties, high oxidative stability and high viscosity index.

  The base oil used in the present invention may conveniently comprise a mixture of one or more mineral oils and / or one or more synthetic oils in addition to the Fischer-Tropsch derived base oil specified herein. The term “base oil” as used herein may refer to a mixture comprising a plurality of base oils including at least one Fischer-Tropsch derived base oil of the present invention. Mineral oils can include liquid petroleum and solvent-treated or acid-treated mineral lubricating oils of paraffinic, naphthenic, or mixed paraffin / naphthene type, which are further hydrofinished and It may be purified by dewaxing.

  Fischer-Tropsch derived base oil is a highly paraffinic API Group III base oil (defined by API Base Oil Interchangeability Guidelines) that exhibits very good cold flow properties, high oxidative stability and high viscosity index. However, due to the high paraffin content, the dissolving action of base oils is generally low, often resulting in incompatibility with other lubricant components and additives.

  Fischer-Tropsch derived base oils are known in the art. In the context of the present invention, the term “Fischer-Tropsch induction” means that the material is or is derived from a synthetic product of the Fischer-Tropsch condensation process. The term “non-Fischer-Tropsch induction” can be interpreted accordingly. Thus, a significant portion of the Fischer-Tropsch derived base oil becomes a hydrocarbon stream derived directly or indirectly from the Fischer-Tropsch condensation process, with the exception of added hydrogen. Fischer-Tropsch derived base oils may be referred to as GTL (gas-to-liquid) base oils and include base oils sold under the trademark Shell XHVI. For additional information regarding Fischer-Tropsch derived base oils and their preparation, see WO 2009/074572, the teachings of which are incorporated herein by specific reference.

  Typically, the aromatic content of Fischer-Tropsch derived base oils (generally determined by ASTM 4629) will be less than 1 wt%, preferably less than 0.5 wt%, more preferably 0.1 wt% %. The base oil typically has a total paraffin content of at least 80 wt%, preferably at least 85 wt%, more preferably at least 90 wt%, even more preferably at least 95 wt%, and most preferably at least 99 wt%. Have. In addition, Fischer-Tropsch derived base oils typically have a saturate content (IP-368, ASTM D2007, ASTM D7419, greater than 98 wt%, preferably greater than 99 wt%, more preferably greater than 99.5 wt%, Or any other chromatographic method that will give similar results). The Fischer-Tropsch derived base oil can have a maximum n-paraffin content of 0.5% by weight. Fischer-Tropsch derived base oils can be up to about 20%, alternatively between 0.1 and 20%, alternatively between 0.5 and 10%, alternatively between 5 and 15%, alternatively between 5 and 10%. % Content of naphthenic compounds.

Typically, Fischer-Tropsch derived base oils have a kinematic viscosity (ASTM D7042) at 100 ° C. of 2 to 8 mm ² / sec (cSt), preferably greater than 2.5, more preferably greater than 3.0 mm ² / sec. It is measured by. Preferably the Fischer-Tropsch derived base oil, at 100 ° C., 5.0 mm less than ² / sec, preferably less than 4.5 mm ² / sec, more preferably has a kinematic viscosity of less than 4.2 mm ² / sec. In certain embodiments, the Fischer-Tropsch derived base oil is 100 ° C., between 2.5 and 5 mm ² / sec (cSt), or between 3 and 4.5 mm ² / sec (cSt), or 4 Having a kinematic viscosity between 0.0 and 4.2 mm ² / sec (cSt).

Furthermore, Fischer-Tropsch derived base oils are typically measured by kinematic viscosity at 40 ° C. (ASTM D7042) of 10 to 100 mm ² / sec (cSt), or 15 to 50 mm ² / sec (cSt). ).

  The Fischer-Tropsch derived base oil also preferably has a pour point (measured by ASTM D5950) of less than -30 ° C, more preferably less than -40 ° C, and most preferably less than -45 ° C. In certain embodiments, the pour point is between −30 ° C. and −40 ° C., or between −40 ° C. and −45 ° C.

  The flash point of Fischer-Tropsch derived base oil (measured according to ASTM D92) is higher than 120 ° C, preferably higher than 130 ° C, more preferably still higher than 140 ° C. Alternatively, the flash point can be between 120 ° C and 130 ° C, or between 130 ° C and 140 ° C.

  The Fischer-Tropsch derived base oil preferably has a viscosity index (measured by ASTM D2270) in the range of 100 to 200. Preferably, the Fischer-Tropsch derived base oil has a viscosity index of at least 125, preferably at least 130. The viscosity index is preferably less than 180, and preferably less than 150. In certain embodiments, the viscosity index is between 125 and 180, or between 130 and 150.

  If the Fischer-Tropsch derived base oil contains a blend of two or more Fischer-Tropsch derived base oils, the above values apply to a blend of two or more Fischer-Tropsch derived base oils.

  The GTL3 base oil used herein has a kinematic viscosity at 100 ° C. of between about 2 and 4 cSt, or between 2.2 and 3.2 cSt, or between 2.6 and 2.9 cSt, and at least Refers to a Fischer-Tropsch derived base oil having a saturate content of about 98.5 wt%, an aromatic content of about 0.7 wt% or less, and a Noack volatility of about 42 wt%.

  The GTL4 base oil used herein has a kinematic viscosity at 100 ° C. of between about 3.5 and 5 cSt, or between 4 and 4.2 cSt, a saturate content of at least about 99% by weight, Refers to a Fischer-Tropsch derived base oil having a saturate content of 0.7 wt% or less and a Noack volatility of about 13.5 wt%.

  In addition to Fischer-Tropsch derived base oils, additive concentrates include one kind of mineral derived base oils including group IV base oils according to the definition of the American Petroleum Institute (API) and so-called synthetic base oils (such as PAO). The above non-Fischer-Tropsch derived base oil may be included. These API categories are defined in API Publication 1509, 15th edition, Appendix E, July 2009.

  In certain embodiments, the lubricant composition of the present invention comprises a blend of two Fischer-Tropsch derived base oils, the blend having a kinematic viscosity between 2.5 and 3.5 cSt at 100 ° C. A first Fischer-Tropsch derived base oil having a second Fischer-Tropsch derived base oil having a kinematic viscosity at 100 ° C. of between 3.5 and 4.5 cSt. In certain embodiments, the blend of two Fischer-Tropsch derived base oils has a maximum of 12% by weight of the first Fischer-Tropsch derived base oil and at least 88% by weight of the second Fischer-Tropsch derived base oil. Or a first Fischer-Tropsch derived base oil between 0.5 and 3% by weight and a second Fischer-Tropsch derived base oil between 97 and 99.5% by weight. Or a first Fischer-Tropsch derived base oil between 3 and 6% by weight and a second Fischer-Tropsch derived base oil between 94 and 97% by weight, or the first Fischer-Tropsch derived base oil. Containing between 6 and 9% by weight of the derived base oil and between 91 and 94% by weight of the second Fischer-Tropsch derived base oil. To be, or become the first Fischer-Tropsch derived base oil between 9 to 12 wt%, and a second Fischer-Tropsch derived base oils that contain between 88 91% by weight. In certain embodiments, a blend of two Fischer-Tropsch derived base oils comprises between 1 and 12% by weight of the first Fischer-Tropsch derived base oil and 88% of the second Fischer-Tropsch derived base oil. From 1 to 99% by weight, or from 0.5 to 4% by weight of the first Fischer-Tropsch derived base oil and from 96 to 99.5% by weight of the second Fischer-Tropsch derived base oil. Or a first Fischer-Tropsch derived base oil between 4 and 8% by weight and a second Fischer-Tropsch derived base oil between 92 and 96% by weight. Alternatively, between 8 and 12% by weight of the first Fischer-Tropsch derived base oil and 88 to 92 of the second Fischer-Tropsch derived base oil It will contain between the amount%.

  The resulting lubricant composition will have a NOACK volatility (tested according to ASTM D-5800) of less than 15 wt%, alternatively less than 14 wt%, alternatively less than 13 wt%, alternatively less than 12 wt%. .

  The resulting lubricant composition has a kinematic viscosity (ASTM) at 100 ° C. of between 3 and 10 cSt, alternatively between 3 and 5 cSt, alternatively between 4 and 6 cSt, alternatively between 5 and 8 cSt, alternatively between 6 and 9 cSt. Will be tested according to D445). In certain other embodiments, the kinematic viscosity at 100 ° C. does not exceed 8 cSt, or does not exceed 5 cSt.

The lubricant composition obtained has at -30 ° C., between 900cP the 6600CP, or between 900cP of 3000 cP, or (to. Tested by ASTM D5 2 93) cold cranking viscosity between 2000cP from 900cP It will be. In certain embodiments, the low temperature cranking viscosity at −30 ° C. will be less than 6600 cP, alternatively less than 2000 cP, alternatively less than 1400 cP, alternatively less than 1200 cP. In certain embodiments, the low temperature cranking viscosity at −30 ° C. is 2000 cP or less, or 1500 cP or less.

The lubricant composition to be obtained, at -35 ° C., between about 1400cP of 6200CP, or between 1400cP of 2500 cP, or (to. Tested by ASTM D5 2 93) cold cranking viscosity between 2000cP from 1500cP Will have. In certain embodiments, the low temperature cranking viscosity at −35 ° C. will be 2500 cP or less, or 2000 cP or less. In certain embodiments, the low temperature cranking viscosity at −35 ° C. is less than 6200 cP, alternatively less than 2500 cP, alternatively less than 2000 cP.

  The resulting lubricant composition has a high temperature high shear (HTHS) at 150 ° C. of between 1.4 and 3.0 cP, alternatively between 1.7 and 2.2 cP, alternatively between 1.7 and 1.9 cP. Will have a viscosity. In certain embodiments, the HTHS viscosity at 150 ° C. is no greater than 2.2 cP, alternatively no greater than 1.9 cP.

  Typically, the base oil (or blend of base oils) used in accordance with the present invention has a kinematic viscosity {according to ASTM D445) at 100 ° C. of between 2.5 and 8 cSt, or between about 3 and 5 cSt. }. According to a preferred embodiment of the invention, the base oil has a kinematic viscosity at 100 ° C. of between 3.5 and 4.5 cSt {according to ASTM D445. }. Where the base oil contains a blend of two or more base oils, the blend preferably has a kinematic viscosity at 100 ° C. of between 3.5 and 4.5 cSt.

  Preferably, the lubricant composition according to the invention has a viscosity at −35 ° C. (according to ASTM D5293) of less than 6200 cP (1 cP is equal to 1 mPas), preferably less than 5500 cP, more preferably less than 5000 cP. And even more preferably less than 4500 cP, or in certain embodiments less than 4000 cP or less than 3500 cP. Typically, the viscosity at -35 ° C is greater than 2000 cP. In certain embodiments, the viscosity is between about 2000 and 4000 cP, alternatively between about 4000 and 6000 cP, alternatively between about 5000 and 6200 cP.

  Preferably, the high temperature high shear viscosity (“HTHS”; according to ASTM D4683) of the composition according to the invention is less than 2.6 cP, preferably less than 2.0 cP, more preferably less than 1.9 cP. Typically, HTHS is greater than 1.5 cP. In certain embodiments, the HTHS is between 1.5 and 2.6 cP, alternatively between about 1.5 and 2 cP, alternatively between about 1.5 and 1.9 cP.

  The lubricant composition according to the invention has a Noack volatility (according to ASTM D5800) of less than 15% by weight. Typically, the Noack volatility (according to ASTM D5800) of the lubricant composition is between 1 and 15% by weight, alternatively between 10 and 14% by weight, alternatively between 11 and 13.5% by weight. Between. In certain embodiments, the Noack volatility is less than 14.6 wt%, alternatively less than 14 wt%, alternatively less than 13.5 wt%, alternatively less than 13 wt%. In certain embodiments, the Noack volatility of the lubricant composition is less than 12.5 wt%, alternatively less than 12 wt%, alternatively less than 11.5 wt%, alternatively less than 11 wt%. Yes, or less than 10% by weight.

  Lubricating compositions according to the present invention comprise antioxidants, antiwear additives, dispersants, detergents, overbased detergents, extreme pressure additives, friction modifiers, viscosity index improvers, pour point depressants, metal One or more additives may further be included such as mobilizing agents, corrosion inhibitors, demulsifiers, antifoaming agents, sealing compatibilizers, and additive diluent base oils. Those skilled in the art are familiar with these and other additives and will not be discussed in further detail herein. Specific examples of such additives are described, for example, in Kirk-Othmer Encyclopedia of Chemical Technology, 3rd edition, volume 14, pages 477-526. Antioxidants that can be used conveniently are phenyl-naphthylamine (such as “IRGANOX L-O6” available from Ciba Specialty Chemicals) and diphenylamine (such as “IRGANOX L-57” available from Ciba Specialty Chemicals). For example, those disclosed in WO 2007/045629 and EP 1058820, phenolic antioxidants and the like are included. The teachings of WO 2007/045629 and EP 1058820 are incorporated herein by reference.

  Antiwear additives that can be added include zinc-containing compounds such as zinc dithiophosphates selected from dialkyl-, diaryl-, and / or alkylaryl-zinc dithiophosphates, molybdenum-containing compounds, boron-containing compounds, and substitutions. And ashless antiwear additives such as unsubstituted thiophosphoric acid and their salts. Examples of molybdenum-containing compounds can include molybdenum dithiocarbamate, trinuclear molybdenum compounds (described in WO 1998/26030), molybdenum sulfide, and molybdenum dithiophosphate. Boron-containing compounds that can be used include boric acid esters, borated fatty amines, borated epoxides, alkali metal (or mixed alkali or alkaline earth metal) borates, and borated overbased metal salts. The dispersant used is preferably an ashless dispersant. Suitable ashless dispersants can include polybutylene succinimide polyamines and Mannic base type dispersants.

  Examples of viscosity index improvers that can be used in the lubricating compositions of the present invention include styrene-butadiene star copolymers, styrene-isoprene star copolymers, and polymethacrylate copolymers, and ethylene-propylene copolymers (also as olefin copolymers). Known) and includes crystalline and amorphous types. Dispersants-viscosity index improvers can also be used in the lubricating composition of the present invention. Preferably, the composition according to the invention is 1.0 weight of viscosity index improver concentrate (ie, VI carrier plus “carrier oil” or “diluent”) relative to the total weight of the composition. %, Preferably less than 0.5% by weight. Most preferably, the composition does not include a viscosity index improver concentrate.

  In certain embodiments, the composition according to the invention comprises at least 0.1% by weight of a pour point depressant. For example, alkylated naphthalene and phenolic polymers, polymethacrylates, and maleate / fumarate copolymer esters can be used as pour point depressants. Preferably, a pour point depressant of 0.3% by weight or less is used. In certain embodiments, compounds such as alkenyl succinic acid or its ester moiety, benzotriazole-based compounds, and thiodiazole-based compounds are used as corrosion inhibitors in the lubricating compositions of the present invention. Can do.

  Compounds such as polysiloxanes, dimethylpolycyclohexane, and polyacrylates can be used in the lubricating compositions of the present invention as antifoam agents.

  In certain embodiments, a pour point depressant can be added, such as a conventional polymethacrylate pour point depressant commercially available under the trademark “Infineum 351” from Infineum Additives (Abingdon, UK).

  Compounds that can be used in the lubricating compositions of the present invention as seal fixes or seal compatibilizers include, for example, commercially available aromatic esters. The lubricating composition of the present invention can be prepared by mixing one or more additives and (one or more) base oil.

  In general, the additives present in the composition of the present invention are present in an amount ranging from 0.01 to 35.0% by weight, preferably from 0.05 to 25.0%, based on the total weight of the lubricating composition. It is present in an amount in the range of wt%, more preferably in an amount in the range of 1.0 to 20.0 wt%. Preferably the composition comprises at least 9.0% by weight, preferably at least 10.0% by weight, more preferably at least 11% of an additive package comprising antiwear additives, metal detergents, ashless dispersants, and antioxidants. Contains 0.0% by weight. Alternatively, the composition of the present invention comprises the additive between 10 and 35 wt%, alternatively between 10 and 25 wt%, alternatively between 10 and 20 wt%. In certain embodiments, the lubricating composition according to the present invention may be a so-called “low SAPS” (SAPS = sulfate ash, phosphorus, and sulfur), “medium SAPS”, or “regular SAPS” formulation.

  In one embodiment, the lubricant composition of the present invention comprises a base oil blend, the base oil blend having a first Fischer-Tropsch derived group having a kinematic viscosity at 100 ° C. of between 2.5 and 3.5 cSt. An oil and a second Fischer-Tropsch derived base oil having a kinematic viscosity between 3.5 and 4.5 cSt at 100 ° C., the base oil blend having a Noack volatility of less than 15 wt%. Optionally, the lubricant composition according to the present invention can include an additive package. An optional additive package can include a combination of additives such as antioxidants, zinc-based antiwear additives, ashless dispersants, overbased detergent mixtures, and antifoam agents.

  The properties of the three base oils are presented in Table 1.

  Base oil 1 is a commercially available Group III mineral base oil having a kinematic viscosity (ASTM D445) of about 4.3 cSt at 100 ° C. Base oil 1 is commercially available, for example, under the trademark Yubase 4 from SK Energy (Ulsan, Korea).

  Base oil 2 was a Fischer-Tropsch derived base oil having a kinematic viscosity (ASTM D445) of about 3.89 cSt at 100 ° C. Base oil 2 can be conveniently made, for example, by the method described in WO2002 / 070631, the teachings of which are incorporated herein by reference.

  Base oil 3 is a Fischer-Tropsch derived base oil having a kinematic viscosity (ASTM D445) of about 2.70 cSt at 100 ° C. Base oil 3 can be conveniently produced, for example, by the method described in WO2002 / 070631, the teachings of which are incorporated herein by reference.

  Table 2 presents properties for several compositions including base oil and additive packages. As shown in the table, GTL4 exhibits improved viscosity and volatility compared to the mineral system Yubase 4.

  As used herein, the words “include” and “comprise” and variations thereof may be used interchangeably.

  The singular forms “a”, “an”, and “the” include the plural unless the context clearly indicates otherwise. This means that the event or situation described subsequently may or may not occur. This description includes when an event or situation occurs and when it does not occur.

  Ranges can be described herein from approximately one particular value and / or to other particular values. When representing such a range, it is understood that another embodiment is from one particular value and / or to the other particular value, including all combinations within that range. .

  Throughout this application, when referring to patents or documents, the entire disclosure of these references is the state of the art to which this invention pertains, except where these references contradict claims made herein. Is hereby incorporated by reference into this application to more fully describe.

  Although the invention has been described in detail, it should be understood that various changes, substitutions, and alternatives can be made herein without departing from the principles and scope of the invention. Accordingly, the scope of the invention should be determined by the following claims and their appropriate legal equivalents.

Claims (5)

Including base oil blend and one or more additives, a lubricant composition for use in the crankcase of the engine, the base oil blend comprises a Fischer-Tropsch derived base oil, the base oil blend, 100 A first Fischer-Tropsch derived base oil having a kinematic viscosity between 2.6 and 2.9 cSt at 4 ° C and between 4 and 8 wt% and between 100 and 3.5 and 4.5 cSt a free between the second Fischer-Tropsch derived base oils having from 92 to 96% by weight, the base oil blend obtained has a Noack volatility of less than 15% by weight (ASTM D5800), provided that the first The pour point of the Fischer-Tropsch derived base oil and the pour point of the second Fischer-Tropsch derived base oil are both between −30 ° C. and −45 ° C. . Including base oil blend and one or more additives, a lubricant composition for use in the crankcase of the engine, the base oil blend comprises a Fischer-Tropsch derived base oil, the base oil blend, 100 A first Fischer-Tropsch derived base oil having a kinematic viscosity between 2.6 and 2.9 cSt at 0 C and a kinematic viscosity between 0.5 and 4 wt% and between 3.5 and 4.5 cSt at 100 ° C A second Fischer-Tropsch derived base oil having a viscosity comprised between 96 and 99.5 wt.%, And the resulting base oil blend has a Noack volatility (ASTM D5800) of less than 15 wt. Lubrication, wherein the pour point of the first Fischer-Tropsch derived base oil and the pour point of the second Fischer-Tropsch derived base oil are both between -30 ° C and -45 ° C. Agent composition . A lubricant composition according to claim 1 or 2, the second Fischer-Tropsch derived base oil has a kinematic viscosity of between 4 and 3.7 at 100 ° C., the lubricant composition. A lubricant composition according to any one of claims 1 to 3, antioxidants, antiwear additives, viscosity modifiers, detergents, additives selected from the group consisting of dispersants and defoamer further seen containing an additive package for a lubricant comprising one or more, the lubricant composition is a low temperature cranking viscosity at -35 ° C. or less 2500 cP. A method of lubricating an engine, comprising the step of supplying the lubricant composition according to any of claims 1 to 4 to the engine.