Lubricating oil composition for two-wheeled motor vehicles

Abstract

Disclosed is a lubricating oil composition for two-wheeled motor vehicles, which contains a base oil (A), a metal-based detergent (B), zinc dialkyldithiophosphate (C), and an ashless dispersant (D), wherein: the metal-based detergent (B) contains a Ca phenate (B1) and an Mg sulfonate (B2); and the ashless dispersant (D) contains a boronated imide-based dispersant (D1). Based on the total amount of the lubricating oil composition, the content of Ca atoms derived from the Ca phenate (B1) is 600 to 2,000 ppm by mass, the content of Mg atoms derived from the Mg sulfonate (B2) is 500 ppm by mass or more, the content of phosphorus atoms derived from the zinc dialkyldithiophosphate (C) is 800 ppm by mass or less, and the content of boron atoms derived from the boronated imide-based dispersant (D1) is 150 ppm by mass or more. The base number of the lubricating oil composition is 8.0 mgKOH / g or more as measured in accordance with JIS K 2501 (2003).

Description

Lubricating oil composition for two-wheeled vehicles

[0001] The present invention relates to a lubricating oil composition for motorcycles.

[0002] In systems where the same oil is used for both the engine lubricant and the power transmission lubricant in motorcycles and other vehicles, the lubricant must have the performance required for the engine lubricant as well as the performance required for the power transmission lubricant. Specifically, engine lubricants are required to have various properties, such as wear resistance, cleanliness, heat resistance, oxidation stability, low oil consumption, and low friction loss. On the other hand, to improve the fuel efficiency of power transmission devices such as transmissions, improved power transmission rates and reduced size and weight are required. In particular, from the perspective of ensuring clutch capacity and reducing the weight of the clutch, an increase in the coefficient of friction between the clutch disc and clutch plate is required.

[0003] Patent Document 1 discloses a lubricating oil composition for motorcycles that has a high static friction coefficient for wet clutches, an excellent friction coefficient for power transmission mechanisms, and excellent fuel economy, and contains (A) an organomolybdenum compound, (B) a zinc dialkyldithiophosphate, (C) at least one selected from calcium sulfonate, calcium phenate, and magnesium sulfonate, and (D) a boron-containing ashless dispersant in predetermined ratios. Patent Document 2 also discloses a lubricating oil composition that can meet the performance standards for both compression-ignition heavy-duty applications and spark-ignition passenger car applications, and contains a detergent that provides both calcium and magnesium from one or more of sulfonates, phenates, salicylates, or mixtures thereof, and an antiwear agent and friction modifier containing a metal dialkyldithiophosphate in predetermined ratios.

[0004] JP 2006-328265 A JP 2023-092504 A

[0005] With the 2023 revision of the JASO standard, motorcycle lubricating oils will be evaluated for their ability to prevent low-speed pre-ignition (LSPI). LSPI is a phenomenon in which ignition occurs earlier than the set ignition timing during low-speed driving, and this ignition can lead to abnormal combustion in the engine cylinder. The occurrence of LSPI can cause engine failure. Therefore, in order to suppress the occurrence of LSPI, the inventors have been studying lubricating oil compositions that can achieve the high base number, high-temperature detergency, wear resistance, and clutch characteristics required of motorcycle lubricating oils under conditions where the calcium content is 2000 ppm by mass or less. Here, the addition of anti-wear agents containing phosphorus atoms, such as zinc dithiophosphate, is widely used as a method for improving the wear resistance of lubricating oils. However, it has been found that phosphorus atoms poison exhaust gas catalysts, such as platinum catalysts, which are installed to remove harmful substances from automobile exhaust gases. In recent years, exhaust gas regulations have become increasingly strict from the viewpoint of protecting the global environment, and there is a need to reduce the phosphorus atom content in engine lubricating oils to prevent exhaust gas catalyst poisoning.In contrast, in Patent Document 1, the lubricating oil compositions prepared in the examples all have a phosphorus atom content of 1000 ppm by mass derived from zinc dithiophosphate, which does not satisfy the catalyst poisoning performance required in recent years.On the other hand, Patent Document 2 discloses a lubricating oil composition that can meet the performance standards for both compression ignition heavy-duty applications and spark ignition passenger car applications, but does not evaluate the required performance such as clutch performance and high-temperature detergency required for motorcycle applications, and therefore does not consider a lubricating oil composition that can simultaneously achieve these required performances.

[0006] The present invention has been made in view of the above problems, and has as its object to provide a lubricating oil composition for motorcycles which, even when the calcium content and the phosphorus atom content derived from zinc dithiophosphate are reduced, can achieve the seizure resistance, wear resistance, and high-temperature detergency required for internal combustion engines, while also being able to exhibit a high friction coefficient in wet clutches.

[0007] The present inventors have discovered that a lubricating oil composition for motorcycles containing a base oil, a calcium-based detergent, a zinc dialkyldithiophosphate, and an ashless dispersant, with the contents of these ingredients falling within specific ranges, can solve the above-mentioned problems, and have completed the present invention. That is, the present invention provides the following [1] to

[12] . [1] A lubricating oil composition for motorcycles, comprising a base oil (A), a metallic detergent (B), a zinc dialkyldithiophosphate (C), and an ashless dispersant (D), wherein the metallic detergent (B) comprises a calcium phenate (B1) and a magnesium sulfonate (B2), and the ashless dispersant (D) comprises a boronated imide dispersant (D1), wherein the content of calcium atoms derived from the calcium phenate (B1) is 600 to 2000 ppm by mass, the content of magnesium atoms derived from the magnesium sulfonate (B2) is 500 ppm by mass or more, the content of phosphorus atoms derived from the zinc dialkyldithiophosphate (C) is 800 ppm by mass or less, and the content of boron atoms derived from the boronated imide dispersant (D1) is 150 ppm by mass or more, based on the total amount of the lubricating oil composition, and A lubricating oil composition for motorcycles having a base number of 8.0 mgKOH / g or more as measured in accordance with K2501:2003. [2] The lubricating oil composition for motorcycles according to [1], wherein the calcium phenate (B1) has a base number of 100 to 600 mgKOH / g. [3] The lubricating oil composition for motorcycles according to [1] or [2], wherein the magnesium sulfonate (B2) has a base number of 100 to 600 mgKOH / g. [4] The lubricating oil composition for motorcycles according to any one of [1] to [3], wherein the content of magnesium atoms derived from the magnesium sulfonate (B2) is 600 to 3,000 ppm by mass based on the total amount of the lubricating oil composition for motorcycles. [5] The lubricating oil composition for motorcycles according to any one of [1] to [4], wherein the content of calcium atoms derived from the calcium phenate (B1) is 20 to 80 mass% relative to the total content of metal atoms derived from the metallic detergent (B).[6] The lubricating oil composition for motorcycles according to any one of [1] to [5], wherein the content of magnesium atoms derived from the magnesium sulfonate (B2) is 20 to 80 mass% relative to the total content of metal atoms derived from the metallic detergent (B). [7] The lubricating oil composition for motorcycles according to any one of [1] to [6], wherein the total content of metal atoms derived from the metallic detergent (B) is 1700 ppm by mass or more based on the total amount of the lubricating oil composition for motorcycles. [8] The lubricating oil composition for motorcycles according to any one of [1] to [7], wherein the zinc dialkyldithiophosphate (C) contains a primary zinc dialkyldithiophosphate (C1) and a secondary zinc dialkyldithiophosphate (C2). [9] The lubricating oil composition for motorcycles according to [8], wherein the combined amount of the primary zinc dialkyldithiophosphate (C1) and the secondary zinc dialkyldithiophosphate (C2) is 80 to 100 mass% based on the total amount of the zinc dialkyldithiophosphate (C).

[10] The lubricating oil composition for motorcycles according to any one of [1] to [9], wherein the ashless dispersant (D) further contains a non-boronated imide dispersant (D2).

[11] A lubrication method for lubricating an engine and a transmission of a motorcycle using the lubricating oil composition for motorcycles according to any one of [1] to

[10] .

[12] A method for producing a lubricating oil composition for motorcycles, comprising a step of mixing a base oil (A), a metallic detergent (B), a zinc dialkyldithiophosphate (C), and an ashless dispersant (D), wherein the metallic detergent (B) contains a calcium phenate (B1) and a magnesium sulfonate (B2), and the ashless dispersant (D) contains a boronated imide dispersant (D1), and in the step, the content of calcium atoms derived from the calcium phenate (B1) is 600 to 2000 ppm by mass, the content of magnesium atoms derived from the magnesium sulfonate (B2) is 500 ppm by mass or more, the content of phosphorus atoms derived from the zinc dialkyldithiophosphate (C) is 800 ppm by mass or less, and the content of boron atoms derived from the boronated imide dispersant (D1) is 150 ppm by mass or more, based on the total amount of the lubricating oil composition, and

[11] The method for producing a lubricating oil composition for motorcycles according to any one of [1] to

[10] , wherein the base number measured in accordance with K2501:2003 is 8.0 mgKOH / g or more.

[0008] The present invention can provide a lubricating oil composition for motorcycles that achieves the seizure resistance, wear resistance, and high-temperature detergency required for internal combustion engines, and that is also capable of exhibiting a high friction coefficient in wet clutches, even when the calcium content and the phosphorus atom content derived from zinc dithiophosphate are reduced.

[0009] In this specification, for preferred numerical ranges (e.g., ranges of content, etc.), the lower limit and upper limit values ​​described in stages can be independently combined. For example, from the description "preferably 10 to 90, more preferably 30 to 60," the "preferable lower limit (10)" and the "more preferable upper limit (60)" can be combined to form "10 to 60." Similarly, in this specification, the numerical values ​​of "greater than or equal to," "less than or equal to," "less than," and "more than" in describing numerical ranges can be arbitrarily combined.

[0010] In this specification, the calcium atom content means the value measured in accordance with JPI-5S-38-03.

[0011] [Lubricating Oil Composition for Motorcycles] The lubricating oil composition for motorcycles of this embodiment contains a base oil (A), a metallic detergent (B), a zinc dialkyldithiophosphate (C), and an ashless dispersant (D), wherein the metallic detergent (B) contains a calcium phenate (B1) and a magnesium sulfonate (B2), and the content of calcium atoms derived from the calcium phenate (B1) is 600 to 2000 ppm by mass, the content of magnesium atoms derived from the magnesium sulfonate (B2) is 500 ppm by mass or more, the content of phosphorus atoms derived from the zinc dialkyldithiophosphate (C) is 800 ppm by mass or less, and the content of boron atoms derived from the boronated imide dispersant (D1) is 150 ppm by mass or more, and the base number of the lubricating oil composition is 8.0 mgKOH / g or more, based on the total amount of the lubricating oil composition. Each component contained in the lubricating oil composition for motorcycles of this embodiment will be described below.

[0012] <Base Oil (A)> The base oil (A) contained in the lubricating oil composition for motorcycles of this embodiment may be any oil that contains at least one type selected from mineral oils and synthetic oils.

[0013] Examples of mineral oils include atmospheric residues obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate crude oil, and naphthenic crude oil; distillates obtained by vacuum distillation of these atmospheric residues; and mineral oils obtained by subjecting the distillates to one or more refining treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

[0014] Examples of synthetic oils include poly-α-olefins such as α-olefin homopolymers and α-olefin copolymers (for example, α-olefin copolymers having 8 to 14 carbon atoms, such as ethylene-α-olefin copolymers); isoparaffins; various esters such as polyol esters and dibasic acid esters; various ethers such as polyphenyl ether; polyalkylene glycols; alkylbenzenes; alkylnaphthalenes; and GTL base oils obtained by isomerizing wax produced from natural gas by the Fischer-Tropsch process or the like (GTL wax (Gas To Liquids WAX)).

[0015] The base oil used in this embodiment is preferably a base oil classified into Groups 2 and 3 of the base oil category of the API (American Petroleum Institute), and more preferably a base oil classified into Group 3.

[0016] The base oil (A) may be a mineral oil, either alone or in combination, or a synthetic oil, or may be a combination of one or more mineral oils and one or more synthetic oils.

[0017] There are no particular restrictions on the kinematic viscosity and viscosity index of the base oil (A), but from the viewpoint of improving the wear resistance of the lubricating oil composition, the kinematic viscosity and viscosity index are preferably in the following ranges. The kinematic viscosity of the base oil (A) at 100°C is preferably 4.0 mm ２ / s or more, and more preferably 4.5 mm ２ / s or more, and more preferably 5.0 mm ２ / s or more, and preferably 26.1 mm ２ / s, and more preferably less than 21.9 mm ２ / s, and more preferably less than 16.3 mm ２ The upper and lower limits can be arbitrarily combined, and specifically, it is preferably 4.0 mm / s. ２ / s or more 26.1mm ２ / s, more preferably less than 4.5 mm ２ / s or more 21.9 mm ２ / s, more preferably less than 5.0 mm ２ / s or more 16.3mm ２ / s or less. The viscosity index of the base oil (A) is preferably 80 or more, more preferably 90 or more, even more preferably 100 or more, and still more preferably 105 or more. In this specification, the kinematic viscosity and viscosity index refer to values ​​measured or calculated in accordance with JIS K 2283:2000. When the base oil (A) is a mixed base oil containing two or more types of base oils, the mixed base oil only needs to have a kinematic viscosity and viscosity index within the above ranges.

[0018] In the lubricating oil composition of this embodiment, the content of base oil (A) is not particularly limited, but from the viewpoint of improving wear resistance, it is preferably 60 to 99 mass %, more preferably 65 to 98 mass %, even more preferably 70 to 97 mass %, and particularly preferably 75 to 95 mass %, based on the total amount (100 mass %) of the lubricating oil composition.

[0019] <Metallic Detergent (B)> The lubricating oil composition of this embodiment contains a metallic detergent (B), and the metallic detergent (B) contains predetermined amounts of calcium phenate (B1) and magnesium sulfonate (B2), thereby exhibiting excellent clutch friction characteristics and high-temperature detergency.

[0020] (Calcium Phenate (B1)) From the viewpoint of obtaining a lubricating oil composition having good clutch friction characteristics and high-temperature detergency, the content of calcium atoms derived from the calcium phenate (B1) in the metallic detergent (B) is preferably 20 to 80 mass %, more preferably 30 to 80 mass %, and even more preferably 40 to 70 mass %, based on the total amount of metal atoms derived from the metallic detergent (B) contained in the lubricating oil composition.

[0021] The calcium phenate (B1) may contain sulfur atoms. The content of sulfur atoms in the calcium phenate (B1) is preferably 1.00 to 8.00 mass%, more preferably 2.00 to 6.00 mass%, even more preferably 2.00 to 5.00 mass%, and even more preferably 2.00 to 4.00 mass%. When the content of sulfur atoms in the calcium phenate (B1) is within the above range, the number of polar groups in the molecular structure increases, which is thought to facilitate adsorption to the clutch material and therefore increase the friction coefficient.

[0022] The calcium phenate (B1) may be a neutral salt, a basic salt, an overbased salt, or a mixture thereof, with an overbased salt being particularly preferred. When the calcium phenate (B1) is a neutral salt, the base number of the neutral salt is preferably 0 to 30 mgKOH / g, more preferably 0 to 25 mgKOH / g, and even more preferably 0 to 20 mgKOH / g. When the calcium phenate (B1) is a basic salt or an overbased salt, the base number of the basic salt or overbased salt is preferably 100 to 600 mgKOH / g, more preferably 120 to 550 mgKOH / g, and even more preferably 130 to 500 mgKOH / g. In this specification, the term "base number" refers to the base number measured by the perchloric acid method in accordance with JIS K2501:2003, "Petroleum products and lubricants - Test method for neutralization number."

[0023] In the lubricating oil composition for motorcycles of this embodiment, the content of calcium phenate (B1) is 600 to 2000 ppm by mass, calculated as calcium atoms, based on the total amount of the lubricating oil composition, and in order to obtain a lubricating oil composition with particularly good high-temperature detergency, the content is preferably 700 ppm by mass or more, more preferably 800 ppm by mass or more, and even more preferably 900 ppm by mass or more; therefore, more specifically, the content is preferably 700 to 2000 ppm by mass, more preferably 800 to 2000 ppm by mass, and even more preferably 900 to 2000 ppm by mass.

[0024] In the motorcycle lubricating oil composition of this embodiment, the calcium phenate (B1) content is preferably adjusted so that the calcium atom content falls within the above range, and is preferably 0.30 mass% or more, more preferably 0.40 mass% or more, even more preferably 0.50 mass% or more, still more preferably 0.60 mass% or more, particularly preferably 0.70 mass% or more, and is preferably 2.50 mass% or less, more preferably 2.20 mass% or less, and even more preferably 2.00 mass% or less, based on the total amount (100 mass%) of the motorcycle lubricating oil composition. These upper and lower limits can be arbitrarily combined, and specifically, are preferably 0.30 to 2.50 mass%, more preferably 0.40 to 2.50 mass%, even more preferably 0.50 to 2.20 mass%, still more preferably 0.60 to 2.20 mass%, and particularly preferably 0.70 to 2.00 mass%.

[0025] (Magnesium sulfonate (B2)) From the viewpoint of obtaining a lubricating oil composition having good clutch friction characteristics and high-temperature detergency, the content of magnesium atoms derived from the magnesium sulfonate (B2) in the metallic detergent (B) is preferably 20 to 80 mass %, more preferably 20 to 70 mass %, and even more preferably 30 to 60 mass %, relative to the total amount of metal atoms derived from the metallic detergent (B) contained in the lubricating oil composition.

[0026] The magnesium sulfonate (B2) may be a neutral salt, a basic salt, an overbased salt, or a mixture thereof, with an overbased salt being particularly preferred. When the magnesium sulfonate (B2) is a neutral salt, the base number of the neutral salt is preferably 0 to 30 mgKOH / g, more preferably 0 to 25 mgKOH / g, and even more preferably 0 to 20 mgKOH / g. When the magnesium sulfonate (B2) is a basic salt or an overbased salt, the base number of the basic salt or overbased salt is preferably 100 to 600 mgKOH / g, more preferably 120 to 550 mgKOH / g, and even more preferably 130 to 500 mgKOH / g.

[0027] In the lubricating oil composition for motorcycles of this embodiment, the content of the magnesium sulfonate (B2) is 500 ppm by mass or more, calculated as magnesium atoms, based on the total amount of the lubricating oil composition. In order to obtain a lubricating oil composition with particularly good high-temperature detergency and wear resistance, the content is preferably 600 ppm by mass or more, more preferably 700 ppm by mass or more, and even more preferably 800 ppm by mass or more. On the other hand, from the viewpoint of LSPI prevention performance, the content is preferably 3000 ppm by mass or less, more preferably 2500 ppm by mass or less, and even more preferably 2000 ppm by mass or less; therefore, more specifically, the content is preferably 600 to 3000 ppm by mass, more preferably 700 to 2500 ppm by mass, and even more preferably 800 to 2000 ppm by mass.

[0028] In the motorcycle lubricating oil composition of this embodiment, the content of the magnesium sulfonate (B2) is preferably adjusted so that the content in terms of magnesium atoms falls within the above range, and is preferably 0.50 mass% or more, more preferably 0.70 mass% or more, even more preferably 0.90 mass% or more, particularly preferably 1.00 mass% or more, based on the total amount (100 mass%) of the motorcycle lubricating oil composition, and is preferably 2.50 mass% or less, more preferably 2.20 mass% or less, even more preferably 2.00 mass% or less, particularly preferably 1.90 mass% or less. These upper and lower limits can be arbitrarily combined, and specifically, are preferably 0.50 to 2.50 mass%, more preferably 0.70 to 2.20 mass%, even more preferably 0.90 to 2.00 mass%, and particularly preferably 1.00 to 1.90 mass%.

[0029] Furthermore, in the lubricating oil composition for motorcycles of this embodiment, it is particularly preferred from the standpoint of high-temperature detergency if the content of calcium phenate (B1) is 950 ppm by mass or more in terms of calcium atom equivalent, based on the total amount of the lubricating oil composition, and the content of magnesium sulfonate (B2) is 1400 ppm by mass or more in terms of magnesium atom equivalent, based on the total amount of the lubricating oil composition, or if the content of calcium phenate (B1) is 1700 ppm by mass or more in terms of calcium atom equivalent, based on the total amount of the lubricating oil composition, and the content of magnesium sulfonate (B2) is 900 ppm by mass or more in terms of magnesium atom equivalent, based on the total amount of the lubricating oil composition.

[0030] The metallic detergent (B) may further contain other metallic detergents.

[0031] From the viewpoint of improving detergency, the metal atom contained in the other metal-based detergent is preferably a metal atom selected from alkali metal atoms and alkaline earth metal atoms, more preferably a sodium atom, calcium atom, magnesium atom, or barium atom, even more preferably a calcium atom or magnesium atom, and even more preferably a calcium atom. Furthermore, the other metal-based detergent is preferably a metal sulfonate or metal salicylate, more preferably a metal sulfonate, and particularly preferably calcium sulfonate. In other words, the other metal-based detergent is preferably calcium sulfonate (B3). The content of calcium sulfonate (B3) in the other metal-based detergent is preferably 70 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 90 to 100 mass%, and even more preferably 95 to 100 mass%, based on the total amount (100 mass%) of the other metal-based detergents contained in the lubricating oil composition.

[0032] The details of the other metal-based detergents are described below, and the details of the calcium sulfonate (B3) are similar. The other metal-based detergents may be neutral salts, basic salts, overbased salts, or mixtures thereof. When the other metal-based detergents are neutral salts, the base number of the neutral salts is preferably 0 to 30 mgKOH / g, more preferably 0 to 25 mgKOH / g, and even more preferably 0 to 20 mgKOH / g. When the other metal-based detergents are basic salts or overbased salts, the base number of the basic salts or overbased salts is preferably 100 to 600 mgKOH / g, more preferably 200 to 550 mgKOH / g, and even more preferably 250 to 500 mgKOH / g.

[0033] In the lubricating oil composition for motorcycles of this embodiment, the content of the other metallic detergents as converted into metal atoms is not particularly limited, but is, for example, preferably 50 to 8000 ppm by mass, more preferably 100 to 5000 ppm by mass, even more preferably 400 to 3500 ppm by mass, and still more preferably 700 to 2500 ppm by mass, based on the total amount of the lubricating oil composition.

[0034] In the lubricating oil composition for motorcycles of this embodiment, the content of the other metallic detergents is preferably adjusted so that the content calculated as metal atoms falls within the above range; specifically, it is preferably 0.10 to 3.00 mass %, more preferably 0.20 to 2.00 mass %, even more preferably 0.30 to 1.50 mass %, and particularly preferably 0.35 to 1.00 mass %, based on the total amount (100 mass %) of the lubricating oil composition for motorcycles.

[0035] In the lubricating oil composition for motorcycles of this embodiment, the content of the metallic detergent (B) is preferably 1.70 mass% or more, more preferably 1.80 mass% or more, even more preferably 1.90 mass% or more, particularly preferably 2.00 mass% or more, and is preferably 4.00 mass% or less, more preferably 3.50 mass% or less, even more preferably 3.30 mass% or less, particularly preferably 3.20 mass% or less, and these upper and lower limits can be arbitrarily combined, specifically, 1.70 to 4.00 mass%, more preferably 1.80 to 3.50 mass%, more preferably 1.90 to 3.30 mass%, and particularly preferably 2.00 to 3.20 mass%. Furthermore, from the viewpoint of high-temperature detergency, the content of the metallic detergent (B) is preferably 2.40 mass% or more, more preferably 2.50 mass% or more, based on the total amount of the lubricating oil composition.

[0036] Furthermore, in the lubricating oil composition for motorcycles of this embodiment, the total content of metal atoms derived from the metallic detergent (B) is preferably 1700 ppm by mass or more, more preferably 1800 ppm by mass or more, even more preferably 1900 ppm by mass or more, and particularly preferably 2000 ppm by mass or more, based on the total amount of the lubricating oil composition. Also, it is preferably 4000 ppm by mass or less, more preferably 3500 ppm by mass or less, even more preferably 3300 ppm by mass or less, and particularly preferably 3200 ppm by mass or less. These upper and lower limits can be arbitrarily combined, and specifically, it is preferably 1700 to 4000 ppm by mass, more preferably 1800 to 3500 ppm by mass, even more preferably 1900 to 3300 ppm by mass, and particularly preferably 2000 to 3200 ppm by mass.

[0037] <Zinc dialkyldithiophosphate (C)> The lubricating oil composition of this embodiment further contains zinc dialkyldithiophosphate (C). Zinc dialkyldithiophosphate (C) has the effect of improving wear resistance, but the lubricating oil composition of this embodiment uses calcium phenate (B1) and magnesium sulfonate (B2) in combination to reduce the content of zinc dialkyldithiophosphate (C). Even when the phosphorus content derived from zinc dialkyldithiophosphate (C) is 800 ppm by mass or less based on the total amount of the lubricating oil composition, excellent wear resistance and clutch friction characteristics can be obtained. One type of zinc dialkyldithiophosphate (C) may be used alone, or two or more types may be used in combination.

[0038] Examples of the zinc dialkyldithiophosphate (C) include compounds represented by the following general formula (c-1):

[0039] (In the formula, R １１ ~R １４ each independently represents a hydrocarbon group having 1 to 24 carbon atoms.

[0040] R １１ ~R １４Examples of the hydrocarbon group represented by include a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkenyl group having 3 to 24 carbon atoms, a cycloalkyl group or a linear or branched alkylcycloalkyl group having 5 to 13 carbon atoms, an aryl group or a linear or branched alkylaryl group having 6 to 18 carbon atoms, and an arylalkyl group having 7 to 19 carbon atoms, and among these, a linear or branched alkyl group having 1 to 24 carbon atoms is preferred, and a branched alkyl group having 1 to 24 carbon atoms is more preferred. The branched alkyl group preferably has 2 to 12 carbon atoms, more preferably 3 to 11 carbon atoms, and even more preferably 4 to 10 carbon atoms. Examples of branched alkyl groups having 1 to 24 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a tert-pentyl group, an isohexyl group, a 2-ethylhexyl group, an isononyl group, an isodecyl group, an isotridecyl group, an isostearyl group, and an isoicosyl group, and among these, a 2-ethylhexyl group is preferred.

[0041] The zinc dialkyldithiophosphate (C) is preferably selected from primary zinc dialkyldithiophosphate (C1) and secondary zinc dialkyldithiophosphate (C2). The total content of the primary zinc dialkyldithiophosphate (C1) and secondary zinc dialkyldithiophosphate (C2) is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and particularly preferably 95 to 100 mass%, based on the total amount of the zinc dialkyldithiophosphate (C).

[0042] In the lubricating oil composition of this embodiment, the content of phosphorus atoms derived from the zinc dialkyldithiophosphate (C) is not particularly limited as long as it is 800 ppm by mass or less based on the total amount of the lubricating oil composition, but from the viewpoint of suppressing poisoning of the exhaust gas catalyst, it is preferably 700 ppm by mass or less, more preferably 650 ppm by mass or less, and even more preferably 620 ppm by mass or less, and from the viewpoint of improving wear resistance, it is preferably 100 ppm by mass or more, more preferably 400 ppm by mass or more.

[0043] In the lubricating oil composition of this embodiment, the content of zinc dialkyldithiophosphate (C) is preferably adjusted so that the content in terms of phosphorus atoms falls within the above range; specifically, from the viewpoint of suppressing poisoning of the exhaust gas catalyst, it is preferably 1.2 mass % or less, more preferably less than 1.0 mass %, and even more preferably less than 0.90 mass %, based on the total amount (100 mass %) of the lubricating oil composition; and from the viewpoint of improving wear resistance, it is preferably 0.10 mass % or more, more preferably 0.50 mass % or more.

[0044] <Ashless Dispersant (D)> The lubricating oil composition of this embodiment contains an ashless dispersant (D) containing a boronated imide dispersant (D1). Examples of the boronated imide dispersant (D1) include one or more compounds selected from the group consisting of boron-modified succinic monoimides such as alkenyl succinic acid monoimides and alkyl succinic acid monoimides, and boron-modified succinic bisimides such as alkenyl succinic acid bisimides and alkyl succinic acid bisimides.

[0045] The ashless dispersant (D) may further contain a non-boronated imide dispersant (D2). Examples of the non-boronated imide dispersant (D2) include one or more compounds selected from the group consisting of succinic acid monoimides such as alkenyl succinic acid monoimides and alkyl succinic acid monoimides, and succinic acid bisimides such as alkenyl succinic acid bisimides and alkyl succinic acid bisimides.

[0046] The content (blending amount) of the ashless dispersant (D) is preferably 1.0 to 10.0 mass%, more preferably 2.5 to 8.0 mass%, even more preferably 3.5 to 6.0 mass%, and still more preferably 4.2 to 6.0 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0047] The ashless dispersant (D) preferably contains a boron-modified alkenyl succinimide (D-1) and a non-boron-modified alkenyl succinimide (D-2). Examples of the non-boron-modified alkenyl succinimide (D-2) include alkenyl succinic acid monoimides represented by the following general formula (d-1) or alkenyl succinic acid bisimides represented by the following general formula (d-2). Furthermore, the non-boron-modified alkenyl succinimide (D-2) may also be a modified alkenyl succinimide obtained by reacting a compound represented by the following general formula (d-1) or (d-2) with one or more selected from alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds, and organic acids. Examples of the boron-modified alkenyl succinimide (D-1) include boron-modified alkenyl succinimides represented by the following general formula (d-1) or (d-2).

[0048]

[0049] In the above general formulas (d-1) and (d-2), R Ａ , R Ａ１ and R Ａ２ are each independently an alkenyl group having a mass average molecular weight (Mw) of 500 to 3,000, preferably 1,000 to 3,000. Ｂ , R Ｂ１ and R Ｂ２ are each independently an alkylene group having 2 to 5 carbon atoms. x1 is an integer of 1 to 10, preferably an integer of 2 to 5, and more preferably 3 or 4. x2 is an integer of 0 to 10, preferably an integer of 1 to 4, and more preferably 2 or 3.

[0050] R Ａ , R Ａ１ and R Ａ２ Examples of alkenyl groups that can be selected for include polybutenyl groups, polyisobutenyl groups, and ethylene-propylene copolymers. Among these, polybutenyl groups and polyisobutenyl groups are preferred.

[0051] The non-boron-modified alkenyl succinimide (D-2) can be produced, for example, by reacting alkenyl succinic anhydride obtained by reacting a polyolefin with maleic anhydride with a polyamine. Examples of the polyolefin include polymers obtained by polymerizing one or more α-olefins having 2 to 8 carbon atoms, with a copolymer of isobutene and 1-butene being preferred. Examples of the polyamine include single diamines such as ethylenediamine, propylenediamine, butylenediamine, and pentylenediamine; polyalkylenepolyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, di(methylethylene)triamine, dibutylenetriamine, tributylenetetramine, and pentapentylenehexamine; and piperazine derivatives such as aminoethylpiperazine.

[0052] The boron-modified alkenyl succinimide (D-1) can be produced, for example, by reacting the alkenyl succinic anhydride obtained by the reaction of the above-mentioned polyolefin with maleic anhydride with the above-mentioned polyamine and boron compound. Examples of the boron compound include boron oxide, boron halide, boric acid, boric anhydride, boric acid ester, and ammonium salt of boric acid.

[0053] From the viewpoint of improving detergency, the mass ratio of the amount of boron atoms to the amount of nitrogen atoms (B / N ratio) contained in the boronated imide dispersant (D1) is preferably 0.3 or more, more preferably 0.5 or more, even more preferably 0.6 or more, still more preferably 0.8 or more, and particularly preferably 0.9 or more.

[0054] In the lubricating oil composition of this embodiment, the content of the boronated imide dispersant (D1) in terms of boron atoms, based on the total amount (100 mass%) of the lubricating oil composition, is preferably 10 to 1000 ppm by mass, more preferably 30 to 700 ppm by mass, even more preferably 50 to 500 ppm by mass, and even more preferably 100 to 400 ppm by mass. The preferred content of the boron-modified alkenyl succinimide (D-1) is similar. The content of the non-boronated imide dispersant (D2) in terms of nitrogen atoms, based on the total amount (100 mass%) of the lubricating oil composition, is preferably 10 to 1000 ppm by mass, more preferably 30 to 700 ppm by mass, even more preferably 50 to 500 ppm by mass, and even more preferably 50 to 400 ppm by mass. The preferred content of the non-boron-modified alkenyl succinimide (D-2) is similar.

[0055] In the lubricating oil composition of this embodiment, the total content of the boronated imide dispersant (D1) and the non-boronated imide dispersant (D2) that may be contained as needed, expressed in terms of nitrogen atoms, is preferably 10 to 3,000 ppm by mass, more preferably 50 to 2,000 ppm by mass, even more preferably 100 to 1,400 ppm by mass, and still more preferably 200 to 1,200 ppm by mass, based on the total amount (100% by mass) of the lubricating oil composition. The same applies to the total content, expressed in terms of nitrogen atoms, of the boron-modified alkenyl succinimide (D-1) and the non-boron-modified alkenyl succinimide (D-2).

[0056] In the lubricating oil composition of this embodiment, the ashless dispersant preferably comprises both a boronated imide dispersant (D1) and a non-boronated imide dispersant (D2). The mass ratio (B / N ratio) of the total amount of boron atoms to the total amount of nitrogen atoms contained in the boronated imide dispersant (D1) and the non-boronated imide dispersant (D2) as a whole is preferably 0.10 to 5.0, more preferably 0.20 to 2.5, even more preferably 0.30 to 1.5, and even more preferably 0.35 to 0.80.

[0057] The lubricating oil composition of this embodiment may further contain a viscosity index improver. Examples of viscosity index improvers include polymers such as non-dispersant poly(meth)acrylates, dispersant poly(meth)acrylates, star polymers, comb polymers, olefin copolymers (e.g., olefin copolymers such as ethylene-propylene copolymers), dispersant olefin copolymers, and styrene copolymers (e.g., styrene-diene copolymers, styrene-isoprene copolymers). These may be used alone or in combination of two or more.

[0058] Here, the viscosity index improver has a mass average molecular weight (Mw) of more than 50,000, preferably 100,000 to 1,500,000, preferably 200,000 to 1,200,000, more preferably 300,000 to 1,000,000, but this is set appropriately depending on the type of polymer. Furthermore, the molecular weight distribution (Mw / Mn) of the viscosity index improver is preferably 8.0 or less, more preferably 5.0 or less, even more preferably 3.0 or less, and even more preferably 1.9 or less, and is usually 1.01 or more. In this specification, the mass average molecular weight (Mw) and number average molecular weight (Mn) of each component are values ​​calculated in terms of standard polystyrene as measured by gel permeation chromatography (GPC).

[0059] The star polymer may be any polymer having a structure in which three or more chain polymers are bonded at one point. Examples of the chain polymer constituting the star polymer include copolymers of vinyl aromatic monomers and conjugated diene monomers, and hydrogenated versions thereof. Examples of vinyl aromatic monomers include styrene, alkyl-substituted styrenes having 8 to 16 carbon atoms, alkoxy-substituted styrenes having 8 to 16 carbon atoms, vinylnaphthalene, and alkyl-substituted vinylnaphthalenes having 8 to 16 carbon atoms. Examples of conjugated diene monomers include conjugated dienes having 4 to 12 carbon atoms, such as 1,3-butadiene, isoprene, piperylene, 4-methylpenta-1,3-diene, 3,4-dimethyl-1,3-hexadiene, and 4,5-diethyl-1,3-octadiene.

[0060] In the lubricating oil composition for motorcycles of this embodiment, the content of the viscosity index improver, converted into a resin content, is preferably 0.5 to 10 mass %, more preferably 1.0 to 8.0 mass %, even more preferably 1.5 to 6.0 mass %, and still more preferably 2.0 to 5.0 mass %, based on the total amount (100 mass %) of the lubricating oil composition.

[0061] From the viewpoint of maintaining high clutch friction, the lubricating oil composition for motorcycles of this embodiment preferably contains a small amount of molybdenum dithiophosphate (MoDTP) or molybdenum dithiocarbamate (MoDTC). More specifically, the total content of molybdenum dithiophosphate and molybdenum dithiocarbamate is preferably 0.10 mass% or less, more preferably 0.05 mass% or less, and even more preferably 0.01 mass% or less, based on the total amount of the lubricating oil composition, and particularly preferably zero.

[0062] <Other Lubricating Oil Additives> The lubricating oil composition for motorcycles of this embodiment may contain other lubricating oil additives in addition to the above components, as long as the effects of the present invention are not impaired. Examples of other lubricating oil additives include other anti-wear agents, antioxidants, pour point depressants, metal friction modifiers, rust inhibitors, metal deactivators, demulsifiers, and antifoaming agents. These lubricating oil additives may be used alone or in combination of two or more.

[0063] The other anti-wear agents mentioned above are anti-wear agents used for lubricating oils other than the above-mentioned zinc dialkyldithiophosphate (C), and examples thereof include zinc-containing compounds such as zinc phosphate; sulfur-containing compounds such as disulfides, sulfurized olefins, sulfurized oils and fats, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfides; phosphorus-containing compounds such as phosphites, phosphate esters, phosphonate esters, and amine salts or metal salts thereof; and sulfur- and phosphorus-containing anti-wear agents such as thiophosphites, thiophosphate esters, thiophosphonate esters, and amine salts or metal salts thereof.

[0064] Examples of the antioxidant include amine-based antioxidants, phenol-based antioxidants, molybdenum-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, etc. Among these, one or more selected from amine-based antioxidants and phenol-based antioxidants are preferred.

[0065] Examples of pour point depressants include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates, and polyalkylstyrenes.

[0066] Examples of metal-based friction modifiers include molybdenum-based friction modifiers such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdic acid.

[0067] Examples of the rust inhibitor include fatty acids, alkenyl succinic acid half esters, fatty acid soaps, alkyl sulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, oxidized paraffins, and alkyl polyoxyethylene ethers.

[0068] Examples of metal deactivators include benzotriazole-based compounds, tolyltriazole-based compounds, thiadiazole-based compounds, imidazole-based compounds, and pyrimidine-based compounds.

[0069] Examples of demulsifiers include anionic surfactants such as sulfate salts of castor oil and petroleum sulfonates; cationic surfactants such as quaternary ammonium salts and imidazolines; polyoxyalkylene polyglycols and esters of dicarboxylic acids thereof; and alkylene oxide adducts of alkylphenol-formaldehyde polycondensates.

[0070] Examples of the antifoaming agent include silicone-based antifoaming agents, fluorosilicone oils, fluorine-based antifoaming agents such as fluoroalkyl ethers, and polyacrylate-based antifoaming agents.

[0071] The contents of the above-mentioned other lubricating oil additives can be adjusted as appropriate within a range that does not impair the effects of the present invention, but each of them is typically 0.001 to 15 mass %, preferably 0.005 to 10 mass %, more preferably 0.01 to 7 mass %, and even more preferably 0.03 to 5 mass %, based on the total amount (100 mass %) of the lubricating oil composition for motorcycles.

[0072] In the lubricating oil composition for motorcycles of this embodiment, the total content of component (A), component (B), component (C) and component (D) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 60 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, and still more preferably 90 mass% or more, and is 100 mass% or less.

[0073] [Various Properties of Motorcycle Lubricating Oil Composition] The motorcycle lubricating oil composition of this embodiment has a base number of 8.0 mgKOH / g or more, preferably 8.5 mgKOH / g or more, and more preferably 9.0 mgKOH / g or more, as measured in accordance with JIS K2501: 2003, from the viewpoints of high-temperature detergency and wear resistance. The method for measuring the base number is, more specifically, the method used in the examples described below.

[0074] The kinematic viscosity at 100°C of the lubricating oil composition for motorcycles of this embodiment is preferably 4.1 to 20.0 mm ２ / s, more preferably 5.0 to 15.0 mm ２ / s, more preferably 6.1 to 12.5 mm ２ The kinematic viscosity at 40°C of the lubricating oil composition for motorcycles of this embodiment is preferably 20.0 to 120.0 mm / s. ２ / s, more preferably 30.0 to 90.0 mm ２ / s, more preferably 35.0 to 70.0 mm ２ The viscosity index of the lubricating oil composition for motorcycles of this embodiment is preferably 110 or greater, more preferably 140 or greater, even more preferably 160 or greater, and particularly preferably 180 or greater.

[0075] The lubricating oil composition for motorcycles of this embodiment preferably has a static friction index (SFI) of more than 2.00 as measured in accordance with JASO M348 3.3.2.

[0076] Furthermore, the lubricating oil composition for motorcycles of this embodiment preferably has a rating of 2.0 or more, more preferably 4.0 or more, and even more preferably 8.0 or more, as measured in the hot tube test described in the Examples below.

[0077] Furthermore, the lubricating oil composition for motorcycles of this embodiment preferably exhibits a wear amount of 30 mg or less as measured in the wear resistance test described in the examples below.

[0078] [Uses of Lubricating Oil Composition] The lubricating oil composition of this embodiment is used in two-wheeled vehicles in which the same oil is used for both the engine and power transmission.

[0079] The present embodiment also provides a lubrication method for lubricating the engine and transmission of a motorcycle using the above-mentioned lubricating oil composition for a motorcycle. Note that with regard to the lubricating oil composition for a motorcycle in the above-mentioned lubrication method, the preferred aspects of each component and the preferred properties of the lubricating oil composition for a motorcycle are as described above.

[0080] [Method for producing a lubricating oil composition for motorcycles] The present embodiment also provides a method for producing the lubricating oil composition for motorcycles, which comprises the step of mixing the base oil (A), metal-based detergent (B), zinc dialkyldithiophosphate (C), and ashless dispersant (D). The preferred aspects of each component in the production method and the preferred properties of the lubricating oil composition for motorcycles are as described above.

[0081] Next, the present embodiment will be described in more detail with reference to examples, but the present embodiment is not limited to these examples. The various properties of the components used in the examples and comparative examples and the resulting lubricating oil compositions were measured by the following methods.

[0082] <Kinematic Viscosity and Viscosity Index> Measured or calculated in accordance with JIS K 2283:2000.

[0083] Examples 1 to 11 and Comparative Examples 1 to 6 Lubricating oil compositions were prepared by adding the base oils and various additives shown below in the amounts shown in Tables 1 and 2 and mixing thoroughly. Details of the base oils and various additives used in the examples and comparative examples are as follows:

[0084] (Base oil (A)) Base oil 1: Hydrorefined mineral oil classified as Group 2 in the API base oil category (150 neutral, kinematic viscosity at 40°C = 30.60 mm ２ / s, 100℃ kinematic viscosity = 5.29mm ２ / s, viscosity index = 104) Base oil 2: Hydrotreated mineral oil classified as Group 3 in the API base oil category (kinematic viscosity at 40°C = 19.74 mm ２ / s, 100℃ kinematic viscosity = 4.26mm ２ / s, viscosity index = 122) Base oil 3: Hydrotreated mineral oil classified as Group 3 in the API base oil category (kinematic viscosity at 40°C = 32.69 mm ２ / s, 100℃ kinematic viscosity = 6.01mm ２ / s, viscosity index=132)

[0085] (Metallic detergents (B)) Ca phenate (B1): Overbased calcium phenate (base number: 250 mg KOH / g, calcium atom content: 9.25 mass%, sulfur atom content: 3.3 mass%) Mg sulfonate (B2): Overbased magnesium sulfonate (base number: 405 mg KOH / g, magnesium atom content: 9.3 mass%) Ca sulfonate: Overbased calcium sulfonate (base number: 307 mg KOH / g, calcium atom content: 11.9 mass%)

[0086] (Zinc dialkyldithiophosphates (C)) ZnDTP1 (C1): Primary zinc dialkyldithiophosphate having a structure represented by the above general formula (c-1) (phosphorus atom content: 7.4% by mass, zinc atom content: 8.9% by mass, sulfur atom content: 15.0% by mass) ZnDTP2 (C2): Secondary zinc dialkyldithiophosphate (phosphorus atom content: 7.2% by mass, zinc atom content: 7.85% by mass, sulfur atom content: 14.0% by mass)

[0087] (Ashless Dispersant (D)) Boron-modified alkenyl succinimide (D1): boron-modified alkenyl succinic acid bisimide (a bis-type alkenyl succinimide represented by the general formula (d-2) above. Nitrogen atom content: 1.23 mass%, boron atom content: 1.30 mass%) Non-boron-modified alkenyl succinimide (D2): non-boron-modified alkenyl succinimide (a bis-type non-boron-modified alkenyl succinimide represented by the general formula (d-2) above. Nitrogen atom content: 1.08 mass%)

[0088] (Other additives) Viscosity index improver Pour point depressant Amine antioxidant Antifoaming agent

[0089] The lubricating oil compositions thus prepared were subjected to the following tests, the results of which are shown in Tables 1 and 2.

[0090] [Atomic Contents] The calcium atom content, magnesium atom content, phosphorus atom content, zinc atom content, sulfur atom content, boron atom content and nitrogen atom content in the lubricating oil composition were measured in accordance with ASTM D4951.

[0091] [Base number] The base number was measured by the perchloric acid method in accordance with JIS K2501:2003 "Petroleum products and lubricants - Test method for neutralization number".

[0092] [Evaluation of seizure resistance and wear resistance] The following pin and block were set in a FALEX testing machine described in ASTM D3233, 60 g of the lubricating oil composition to be evaluated was introduced into the test vessel, and the wear amount (mg) of the block and pin was measured under the following conditions: - Test conditions - Test pin: SAE3135 Test block: AISI1137 Rotation speed: 800 rpm Test temperature: 80°C Test load: 1334 N Test time: 60 minutes

[0093] [Hot Tube Test] A hot tube test was carried out on the test oil (prepared lubricating oil composition) in accordance with JPI-5S-55-99 at a test temperature of 290°C for a test time of 16 hours. After the test, the lacquer adhering to the test tube was rated in accordance with JPI-5S-55-99 on a 21-point scale from 0 (black) to 10 (colorless). A higher rating indicates less deposits and better detergency.

[0094] [Clutch Friction Characteristics] The static friction index (SFI), dynamic friction index (DFI), and braking time index (STI) were measured under the following test conditions in accordance with the clutch friction characteristic evaluation test method described in JASO T903:2023, and a static friction index (SFI) of 2.00 or more was deemed to have passed. <Test Conditions> Testing machine: SAE No. 2 testing machine (manufactured by Automax Co., Ltd.) Dynamic friction test: in accordance with JASO M348 3.3.1 Static friction test: in accordance with JASO M348 3.3.2 Test cycle: 1,000 times

[0095]

[0096]

[0097] The lubricating oil compositions prepared in Examples 1 to 11 satisfied the seizure resistance, wear resistance, and high-temperature detergency required for motorcycle lubricating oils, and also exhibited a high friction coefficient in wet clutches. In contrast, the lubricating oil compositions prepared in Comparative Examples 1 to 6 were inferior in any of seizure resistance, wear resistance, high-temperature detergency, and clutch friction characteristics. More specifically, the lubricating oil composition of Comparative Example 1, which contained a low amount of component (B1), and the lubricating oil composition of Comparative Example 6, which contained a low amount of component (D1), exhibited insufficient seizure resistance. Furthermore, the lubricating oil composition of Comparative Example 2, which had a low base number, exhibited insufficient wear resistance and high-temperature detergency. Furthermore, the lubricating oil compositions of Comparative Examples 3 and 4, which did not contain component (B1), exhibited insufficient clutch friction characteristics. In addition, the lubricating oil composition of Comparative Example 5 also exhibited insufficient high-temperature detergency.

Claims

1. A lubricating oil composition for motorcycles, containing base oil (A), metal detergent (B), zinc dialkyldithiophosphate (C), and ashless dispersant (D), wherein the metal detergent (B) contains calcium phenate (B1) and magnesium sulfonate (B2), and the ashless dispersant (D) contains a boronated imide dispersant (D1). The content of calcium atoms derived from the calcium phenate (B1) is 600 to 2000 mass ppm based on the total amount of the lubricating oil composition. The content of magnesium atoms derived from the magnesium sulfonate (B2) is 500 mass ppm or more. The content of phosphorus atoms derived from the zinc dialkyldithiophosphate (C) is 800 mass ppm or less. The content of boron atoms derived from the boronated imide dispersant (D1) is 150 mass ppm or more. And the base number of the lubricating oil composition measured in accordance with JIS K2501:2003 is 8.0 mgKOH / g or more.

2. The lubricating oil composition for motorcycles according to claim 1, wherein the base number of the calcium phenate (B1) is 100 to 600 mgKOH / g.

3. The lubricating oil composition for motorcycles according to claim 1 or 2, wherein the base number of the magnesium sulfonate (B2) is 100 to 600 mgKOH / g.

4. The lubricating oil composition for motorcycles according to any one of claims 1 to 3, wherein the content of magnesium atoms derived from the magnesium sulfonate (B2) is 600 to 3000 mass ppm based on the total amount of the lubricating oil composition for motorcycles.

5. The lubricating oil composition for motorcycles according to any one of claims 1 to 4, wherein the content of calcium atoms derived from the calcium phenate (B1) is 20 to 80 mass% with respect to the total content of metal atoms derived from the metal detergent (B).

6. The lubricating oil composition for motorcycles according to any one of claims 1 to 5, wherein the content of magnesium atoms derived from the magnesium sulfonate (B2) is 20 to 80 mass% with respect to the total content of metal atoms derived from the metal detergent (B).

7. The lubricating oil composition for motorcycles according to any one of claims 1 to 6, wherein the total content of metal atoms derived from the metal detergent (B) is 1700 mass ppm or more based on the total amount of the lubricating oil composition for motorcycles.

8. The zinc dialkyldithiophosphate (C) contains primary zinc dialkyldithiophosphate (C1) and secondary zinc dialkyldithiophosphate (C2), and the lubricating oil composition for motorcycles according to any one of claims 1 to 7.

9. The total content of the primary zinc dialkyldithiophosphate (C1) and the secondary zinc dialkyldithiophosphate (C2) is 80 to 100% by mass based on the total amount of the zinc dialkyldithiophosphate (C), and the lubricating oil composition for motorcycles according to claim 8.

10. The ashless dispersant (D) further contains a non-boronated imide-based dispersant (D2), and the lubricating oil composition for motorcycles according to any one of claims 1 to 9.

11. A lubricating method for lubricating an engine and a transmission of a motorcycle using the lubricating oil composition for motorcycles according to any one of claims 1 to 10.

12. A method for producing a lubricating oil composition for motorcycles, comprising a step of mixing a base oil (A), a metallic detergent (B), a zinc dialkyldithiophosphate (C), and an ashless dispersant (D), wherein the metallic detergent (B) contains calcium phenate (B1) and magnesium sulfonate (B2), and the ashless dispersant (D) contains a boronated imide-based dispersant (D1), and in the step, the content of calcium atoms derived from the calcium phenate (B1) is 600 to 2000 ppm by mass, the content of magnesium atoms derived from the magnesium sulfonate (B2) is 500 ppm by mass or more, the content of phosphorus atoms derived from the zinc dialkyldithiophosphate (C) is 800 ppm by mass or less, the content of boron atoms derived from the boronated imide-based dispersant (D1) is 150 ppm by mass or more, and the mixture is carried out so that the base number measured in accordance with JIS K2501:2003 of the lubricating oil composition is 8.0 mgKOH / g or more, and the method for producing a lubricating oil composition for motorcycles according to any one of claims 1 to 10.

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