CN101319163A - Lubricating oil composition for internal combustion engine - Google Patents

Abstract

The present invention provides a kind of fuel-efficient engine oil with good high-temperature deposition performance, low wear characteristic and long service life. The lubricating oil composition for internal combustion engines of the invention is characterized in that the lubricating oil composition is produced by adding certain amount of alkaline earth detergent containing 0.12 to 0.24 percent metal ingredient by weight ratio, adding certain amount of P-type additive at least including zinc dialkyl dithio (ZnDTP) containing 0.005 to 0.070 percent P by weight ratio and adding certain amount of molybdenum dithiocarbamate (MoDTC) containing 0.030 to 0.075 percent Mo by weight ratio to mineral oil and/or synthesized base oil. The P content in the P-type additive and the Mo content in MoDTC satisfy the following formula (1): 0.5*P + Mo<=0.075 (1 ); [wherein, P represents the P content in the P-type additive of the lubricating composition (wt%);Mo represents the Mo content in MoDTC of th e lubricating composition (wt%)].

Description

Lubricating oil composition for internal combustion engine

technical field

The invention relates to a lubricating oil composition for an internal combustion engine, in particular to a long-life fuel-saving lubricating oil composition for an internal combustion engine with good high-temperature deposition performance and excellent low wear characteristics.

Background technique

In recent years, in order to prevent global warming, it has been urgently required to improve the fuel efficiency of automobiles and to suppress CO ₂ emissions. In order to improve the fuel efficiency of automobiles, it is important to improve the efficiency of the engine. Gasoline engines have always used lean burn, direct-injection, or turbocharger technologies. On the other hand, reducing friction in the engine can also help improve fuel efficiency, so use low-friction materials for sliding parts or use fuel-efficient engine oil.

It is known that in order to manufacture fuel-saving engine oil (engine oil), the following method is more effective: reduce the viscosity of the engine oil, so that the viscosity reaches the viscosity classification specified by the American Society of Automotive Engineers (Society of Automotive Engineers, SAE) J300. 5W-20 or 0W-20, and the deployment of additives to reduce friction (friction modifier, hereinafter, sometimes also referred to as FM), that is, organic molybdenum-based FM such as molybdenum dithiocarbamate (MoDTC) (refer to K.Hoshino et al , Fuel Efficiency of SAE 5W-20 Friction Modified Gasoline Engine Oil, SAE Technical Paper 982506 (1998), and Japanese Patent Laid-Open Publication No. 10-17883).

On the other hand, lean-burn engines and direct-injection engines are more efficient than conventional engines, so the combustion temperature also tends to rise, exposing pistons and the like to higher temperatures. In addition, the turbocharger compresses the air and forcibly supplies it into the cylinder. Therefore, although the power of the engine can be increased compared with a non-supercharged engine (Natural aspiration engine) with the same displacement, it will make the engine Constantly exposed to high temperatures. Therefore, the high-temperature deposition performance of engine oil must also be improved. That is to say, future fuel-saving engine oils are required to have better high-temperature deposition performance than the original engine oils.

Contents of the invention

In view of the above circumstances, an object of the present invention is to provide an engine oil having excellent high-temperature deposition performance and excellent fuel economy.

In order to solve the above-mentioned problems, the inventors of the present invention conducted diligent research and found that a specific amount of an alkaline earth metal-based detergent is blended in a mineral oil and/or a synthetic base oil, and a specific amount of a dialkyl detergent is blended in a specific ratio. The lubricating oil composition prepared from zinc dithiophosphate (ZnDTP) and a specific amount of molybdenum dithiocarbamate (MoDTC) can be used as a fuel-saving engine oil with good high-temperature deposition performance. The present invention was developed based on this knowledge.

That is to say, the present invention is a lubricating oil composition for an internal combustion engine, characterized in that it is blended in mineral oil and/or synthetic base oil in an amount of 0.12% by mass (mass percent) to 0.24% by mass in terms of metal components. % of alkaline earth metal-based cleaning agent, 0.005% to 0.070% by mass of P-based additives containing at least zinc dialkyldithiophosphate (ZnDTP) in terms of phosphorus (P) components, and in terms of molybdenum (Mo) components It is made of molybdenum dithiocarbamate (MoDTC) at 0.030% to 0.075% by mass, and the P component of the P-based additive and the Mo component of the MoDTC satisfy the conditions represented by the following formula (1):

0.5×P+Mo≤0.075 (1)

[wherein, P represents the ratio (mass %) of the P component of the P-based additive in the lubricating oil composition, and Mo represents the ratio (mass %) of the Mo component of MoDTC in the lubricating oil composition].

The lubricating oil composition for an internal combustion engine of the present invention preferably contains the molybdenum dithiocarbamate in an amount of 0.045% by mass to 0.075% by mass as a molybdenum component. Furthermore, the lubricating oil composition for an internal combustion engine of the present invention preferably contains the P-based additive in an amount of 0.005% by mass to 0.050% by mass as a phosphorus component, and preferably contains 0.15% by mass to 0.20% by mass in terms of a metal component. Alkaline earth metal based cleaner. In addition, the base oil of the lubricating oil composition for an internal combustion engine of the present invention preferably has a kinematic viscosity at 100°C of 3.5 mm ^{2 /s} to 5.0 mm ² /s and a viscosity index of 110 to 160.

[Effect of the invention]

By adopting the above constitution, the lubricating oil composition for an internal combustion engine of the present invention is a long-life, fuel-saving engine oil capable of achieving the following special effects, that is, excellent high-temperature deposit performance and relatively low deposit accumulation even after long-term use. less, and can maintain low friction for a long time. Therefore, the lubricating oil composition for internal combustion engines of the present invention can be preferably used in internal combustion engines, especially gasoline engines or turbochargers such as lean burn or direct injection, and can exert a special effect of improving fuel efficiency.

Detailed ways

As the base oil of the lubricating oil composition for an internal combustion engine of the present invention, any of mineral oil, synthetic base oil, and a mixture of mineral oil and synthetic base oil can be used. The kinematic viscosity of the base oil at 100°C is preferably in the range of 3.5 mm ² /s to 5.0 mm ² /s, particularly preferably in the range of 4.0 mm ² /s to 4.5 mm ² /s. Furthermore, the viscosity index of the base oil is preferably in the range of 110-160, particularly preferably in the range of 120-140. In addition, the mineral oil is desirably a high viscosity index lubricating oil base oil having a viscosity index of 120 or more. A high viscosity index lubricating base oil with a viscosity index of 120 or more can be obtained by solvent dewaxing or hydrogenating the resulting oil obtained by hydroisomerizing wax or hydrocracking heavy oil Dewaxing. An example of these production methods will be specifically described below.

Waxes can be hydroisomerized in the following manner: using waxes with a boiling point in the range of 300°C to 600°C and a carbon number in the range of 20 to 70 as raw materials, in the presence of hydrogen with a hydrogen partial pressure of 5MPa to 14MPa, The wax and the hydroisomerization catalyst are brought into contact at a temperature of 300° C. to 450° C. and a liquid hourly space velocity (liquid hour space velocity, LHSV) of 0.1 hr ⁻¹ to 2 hr ⁻¹ . At this time, it is preferable that the conversion rate of linear paraffin (paraffin) is not less than 80%, and the conversion rate of linear paraffin to light fraction is not more than 40%. In addition, raw material waxes include, for example, slack waxes obtained in the solvent dewaxing step of mineral oil-based lubricating oils, or those obtained by Fischer-Tropsch synthesis for synthesizing liquid fuels from hydrocarbon gases and the like. wax etc. Furthermore, examples of the hydroisomerization catalyst include those in which Group 8 metals such as nickel and cobalt, molybdenum, and tungsten are supported on an alumina or silica-alumina carrier. One or more catalysts of Group 6A metals, zeolite catalysts or catalysts containing platinum on a zeolite-containing carrier.

On the other hand, hydrocracking can be carried out by using atmospheric distillate oil, vacuum distillate oil, or bright stock (bright stock) with a boiling point in the range of 300° C. to 600° C. that has undergone hydrodesulfurization and denitrogenation as needed. ), in the presence of hydrogen with a hydrogen partial pressure of 7MPa to 14MPa, at a temperature of 350°C to 450°C, with an LHSV (liquid hourly space velocity) of 0.1hr ^-1 to 2hr ^-1 , the atmospheric distillate oil , vacuum distillate oil or bright stock is in contact with a hydrocracking catalyst. At this time, it is preferable that the cracking rate (the reduction of the fraction greater than or equal to 360° C. in the mass percentage of the product) is 40% to 90%. In addition, examples of hydrocracking catalysts include catalysts in which one or more Group 8 metals such as nickel and cobalt and one or more Group 6A metals such as molybdenum and tungsten are supported on a silica-alumina carrier. .

The lubricating oil fraction can be obtained by distilling off the light fraction from the hydroisomerization product oil or hydrocracking product oil obtained by the above method, but if the fraction is used as it is, generally speaking, the pour point or viscosity is high, And the viscosity index is not high enough. Therefore, the fraction can be dewaxed to remove the wax components, thereby obtaining a lubricating base oil with a %C _p of ndM ring analysis greater than or equal to 80, a pour point of less than or equal to -10°C, and a viscosity index of greater than or equal to 120.

In the case of removing the wax component by solvent dewaxing, it is preferable to distill and separate the light fraction by using a precision distillation device, and perform fractional distillation in advance so that the boiling point obtained by the gas chromatographic distillation method is equal to or greater than The reason why the fraction of 371° C. to less than 491° C. is 70% by mass or more is that the solvent dewaxing treatment can be performed more efficiently. The solvent dewaxing treatment preferably uses, for example, methyl ethyl ketone/toluene (capacity ratio: 1/1) as the dewaxing solvent, the ratio of solvent and oil is in the range of 2/1 to 4/1, and the temperature is -15°C Carried out at ~-40°C.

On the other hand, in the case of removing the wax component by hydrodewaxing, it is preferable to use the method of distilling off light fractions to an extent that does not interfere with hydrodewaxing, and using After dewaxing, distillation separation is performed using a precision distillation apparatus, and fractional distillation is performed so that the fraction having a boiling point of not less than 371° C. and less than 491° C. obtained by gas chromatographic distillation is not less than 70% by mass. The hydrodewaxing is preferably carried out in the presence of hydrogen with a hydrogen partial pressure of 3 MPa to 15 MPa, at a temperature of 320°C to 430°C, and at an LHSV (liquid hourly space velocity) of 0.2hr ^-1 to 4hr ^-1 to make the lubricating oil fraction Contact with the zeolite catalyst so that the pour point of the final lubricating oil base oil is less than or equal to -10°C.

Using the method described above, a lubricating oil base oil with a viscosity index greater than or equal to 120 can be obtained, and further solvent refining or hydrogenation refining can be performed as required.

Furthermore, examples of synthetic base oils include oligomers of α-olefins, diesters synthesized from dibasic acids such as adipic acid and monohydric alcohols, neopentyl glycol, trimethylol, etc. Trimethylolpropane (trimethylolpropane), pentaerythritol (pentaerythritol) and other polyols and polyol esters (polyol Ester) synthesized from monobasic acids, and their mixtures. In addition, a blended oil obtained by appropriately combining a mineral oil and a synthetic base oil can also be used as the base oil of the lubricating oil composition for an internal combustion engine of the present invention.

The zinc dialkyldithiophosphate (ZnDTP) used in the lubricating oil composition for internal combustion engines of the present invention can include compounds represented by the following general formula (2):

[chemical 1]

In the general formula (2), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrocarbon group having 1 to 24 carbon atoms. These hydrocarbon groups are linear or branched alkyl groups with 1 to 24 carbons, linear or branched alkenyl groups with 3 to 24 carbons, or linear or branched alkylcycloalkyl groups, An aryl group having 6 to 18 carbon atoms or a linear or branched alkylaryl group. Also, the alkyl or alkenyl may be any of primary, secondary, and tertiary.

Relative to the total mass of the lubricating oil composition for internal combustion engines, the content of the P-based additive containing at least ZnDTP is 0.005% by mass to 0.070% by mass, preferably 0.005% by mass to 0.050% by mass of the phosphorus (P) element contained in the P-based compound. mass % range. In addition, the lubricating oil composition for an internal combustion engine of the present invention does not substantially contain P-based additives other than ZnDTP, and the content of P-based additives other than ZnDTP is preferably 0.002% by mass or less, and more preferably does not contain P-based additives other than ZnDTP. In addition, the P-based additive refers to an additive composed of a compound containing phosphorus element.

Molybdenum dithiocarbamate (MoDTC) used in the lubricating oil composition for internal combustion engines of the present invention can be represented by the following general formula (3):

[Chem 2]

In the general formula (3), R ⁵ , R ⁶ , R ⁷ and R ⁸ represent straight-chain or branched-chain alkyl or alkenyl groups with 4 to 18 carbons, X represents an oxygen atom or a sulfur atom, and the The ratio of oxygen atoms to sulfur atoms is 1/3 to 3/1. R ⁵ to R ⁸ are preferably alkyl groups, particularly preferably branched chain alkyl groups with 8 to 14 carbon atoms. Specific examples of R ⁵ to R ⁸ include: butyl, 2-ethylhexyl, isotridecyl, octadecyl Alkyl etc. In addition, four R ⁵ to R ⁸ present in one molecule may be the same or different. Furthermore, in the lubricating oil composition for an internal combustion engine of the present invention, two or more MoDTCs having different R ⁵ to R ⁸ may be mixed and used.

The content of MoDTC is in the range of 0.030% to 0.075% by mass, preferably 0.045% to 0.075% by mass, based on the mass of the molybdenum (Mo) element contained in MoDTC, relative to the total mass of the lubricating oil composition for internal combustion engines.

The P-based compound containing at least ZnDTP and MoDTC are prepared in such a manner that the P-based compound is 0.005 mass % to 0.070 mass % as the P component, preferably 0.005 mass % to 0.050 mass %, and the MoDTC is calculated as the Mo component. 0.030% by mass to 0.075% by mass, preferably 0.045% by mass to 0.075% by mass, and within the range of 0.5×P+Mo≦0.075. If the value of 0.5×P+Mo is greater than 0.075, the target high-temperature deposition performance cannot be obtained, for example, the deposit mass of the TEOST 33C test will not be less than or equal to 42 mg. Moreover, if the content of the P-based compound is less than 0.005% by mass in terms of the P component, the target wear resistance cannot be obtained, and if the content of the P-based compound is greater than 0.070% by mass in terms of the P component, it is harmful to exhaust gas. The influence of purification catalyst poisoning becomes greater. On the other hand, if the content of the MoDTC is less than 0.030% by mass based on the Mo component, the targeted fuel-saving performance cannot be obtained, and if the content of the MoDTC is greater than 0.075% by mass based on the Mo component, the targeted high-temperature deposition cannot be obtained. performance. In addition, if the content of MoDTC is equal to or greater than 0.045% by mass based on the Mo component, high sustainability of fuel-saving performance can be obtained.

From the viewpoint of detergency, the lubricating oil composition for an internal combustion engine of the present invention preferably contains an alkaline earth metal-based detergent. The metal-based detergent is preferably at least one alkaline earth metal detergent selected from alkaline earth metal sulfonates, alkaline earth metal phenates, and alkaline earth metal salicylates.

The alkaline earth metal sulfonate may be an alkaline earth metal salt of an alkylaromatic sulfonic acid with a molecular weight of preferably 300-1,500, particularly preferably 400-700, preferably a magnesium salt and/or a calcium salt, particularly preferably a calcium salt.

Described alkaline earth metal phenate can enumerate the alkaline earth metal salt of alkylphenol (alkylphenol), alkylphenolsulfide (alkylphenolsulfide), the Mannich (Mannich) reactant of alkylphenol, particularly magnesium salt and/or Calcium salts, more specifically, compounds represented by the following general formulas (4) to (6):

[Chem 3]

[chemical 4]

[chemical 5]

In the general formulas (4) to (6), R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ each independently represent a straight chain with 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms. Shaped or branched chain alkyl, M ¹ , M ² and M ³ represent alkaline earth metals, preferably calcium and/or magnesium, and x represents 1 or 2.

The alkaline earth metal salicylate can be an alkaline earth metal salt of alkyl salicylic acid, particularly preferably a magnesium salt and/or a calcium salt, more specifically, a compound represented by the following general formula (7):

[chemical 6]

In the general formula (7), R ¹⁵ each independently represent a linear or branched alkyl group with a carbon number of 1 to 30, preferably 6 to 18, n represents an integer of 1 to 4, preferably 1 or 2, M ⁴ represents an alkaline earth metal, preferably calcium and/or magnesium.

The content of the metal-based detergent in the lubricating oil composition for internal combustion engines of the present invention is preferably in the range of 0.12% by mass to 0.24% by mass in terms of metal components, more preferably 0.15% by mass, based on the total mass of the lubricating oil composition for internal combustion engines. The range of mass % - 0.20 mass %. If the content of the metal-based detergent is less than 0.12% by mass in terms of metal components, the targeted cleaning performance cannot be obtained, and if the content of the metal-based detergent is greater than 0.24% by mass in terms of metal components, ash may be deposited in the In the combustion chamber, it is not good.

Furthermore, the lubricating oil composition for an internal combustion engine of the present invention preferably contains an ashless dispersant from the viewpoint of detergency and sludge dispersibility. Examples of ashless dispersants include alkenyl succinimide, alkyl succinimide and their derivatives derived from polyolefin. A representative succinimide can be obtained by making succinic anhydride substituted by a high molecular weight alkenyl or alkyl group, and polyamethylene oxide containing an average of 4 to 10 (preferably 5 to 7) nitrogen atoms in each molecule. It is obtained by reaction of polyalkylene polyamine. The high-molecular-weight alkenyl or alkyl group is preferably a polyisobutenyl group with a number average molecular weight of 700 to 5,000, particularly preferably a polyisobutenyl group with a number average molecular weight of 900 to 3,000.

The polybutenyl succinimide used in the lubricating oil composition for internal combustion engines of the present invention can include compounds represented by the following general formula (8) or general formula (9):

[chemical 7]

[chemical 8]

In the general formula (8) and general formula (9), PIB represents a polybutenyl group, which is a group obtained by using the following polybutene, that is, this polybutene is obtained by using a boron fluoride-based catalyst or chlorinated Aluminum-based catalysts are obtained by polymerizing high-purity isobutene or a mixture of 1-butene and isobutene, and the polybutene group usually contains 5 mol% to 100 mol% of vinylidene (vinylidene) at the end of the polybutene ) group of the base structure. In addition, n is preferably an integer of 2 to 5, particularly preferably an integer of 3 to 4, from the viewpoint of an excellent sludge inhibiting effect.

Furthermore, as a derivative of polybutenyl succinimide, a so-called modified succinimide can be used, that is, a compound represented by the above-mentioned formula (8) or formula (9), and a boron compound such as boric acid or alcohol, Aldehydes, ketones, alkylphenols, cyclic carbonates, organic acids and other oxygen-containing organic compounds, and neutralize part or all of the remaining amino groups and/or imino groups or make them form amido groups. In particular, the boron-containing alkenyl (or alkyl) succinimide obtained by reacting the compound represented by the formula (8) or the formula (9) with a boron compound such as boric acid has the advantages of thermal stability and oxidation stability. more favorable.

The content of the ashless dispersant in the lubricating oil composition for internal combustion engines of the present invention is arbitrary, and is preferably in the range of 0.5% by mass to 15% by mass relative to the total mass of the lubricating oil composition for internal combustion engines.

In the lubricating oil composition for internal combustion engines of the present invention, in addition to the ZnDTP, MoDTC, metal-based detergents and ashless dispersants, ashless antioxidants, viscosity index improvers, pour point depressants, metal Additives such as passivators, rust inhibitors or defoamers.

[Example]

Hereinafter, examples are given to illustrate the present invention in more detail, but the present invention is not limited at all by the following examples.

Mineral oil-based base oil obtained by hydrodewaxing the product oil obtained by hydrocracking heavy oil [kinematic viscosity: 19.9 mm ² /s (40°C), 4.26 ^{mm 2} /s (100°C); viscosity The index is 121], as the base oil.

MoDTC, ZnDTP and other additives were blended in the base oil at the ratio shown in Table 1 to prepare lubricating oil compositions (engine oils) for internal combustion engines of Examples 1-2 and Comparative Examples 1-5. In addition, the values of 0.5×P+Mo are shown in Table 1 together. In addition, the alkaline earth metal-based detergent uses calcium sulfonate, ZnDTP uses a compound in which R ¹ , R ² , R ³ and R ⁴ represented by the general formula (2) are octyl groups, and R ¹ , R ² , R ³ and R ⁴ are butyl and pentyl compounds, and MoDTC uses R ⁵ , R ⁶ , R ⁷ and R ⁸ represented by the general formula (3) as 2-ethylhexyl, and the oxygen atom of X A compound with a sulfur atom ratio (O/S) of 1/1. In addition, other additives are additive mixtures containing alkenyl succinimide, a viscosity index improver, a pour point depressant, and an antifoaming agent, and the same amount of additives was added in all Examples and Comparative Examples.

[Table 1]

The TEOST 33C test was performed on the engine oils of Examples and Comparative Examples in Table 1, respectively, to evaluate the performance of the engine oils. The TEOST 33C test is a project that uses the quality of sediment to evaluate the high-temperature deposition performance. In the ILSAC GF-2 standard, which is the engine oil standard, it is stipulated that the quality of sediment should be less than or equal to 60mg as the qualified standard. According to ASTM D6335, the deposit quality of each of the test engine oils was obtained. Furthermore, the wear resistance of the engine oil to be tested was evaluated by the SHELL four-ball abrasion test, and when the wear resistance was good, it was marked as ○, and when it was bad, it was marked as ×. In addition, the SRV friction test was used to evaluate the fuel-saving performance of the test engine oil, and the fuel-saving performance was marked as ◎, good as ○, and poor as x. These results are shown in Table 2.

[Table 2]

Example 1 Example 2 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative Example 5 TEOST 33C sediment mass (mg) 41.1 41.2 33.5 57.3 44.6 24.5 25.2 wear resistance ○ ○ ○ ○ ○ ○ × Fuel saving ◎ ◎ ○ ◎ ◎ × ○

The above results show that in the mineral oil and/or synthetic base oil shown in the examples, a P-based compound containing at least ZnDTP in an amount of 0.005 mass % to 0.070 mass % in terms of a P component, and 0.030 mass % in terms of a Mo component are blended. mass % to 0.075 mass % MoDTC, and adjust 0.5×P+Mo to be less than or equal to 0.075, the deposit quality of the lubricating oil composition for internal combustion engines in the TEOST 33C test is higher than that stipulated in the ILSAC GF-2 standard 30% or more is further reduced by 30% or more, which shows that the high-temperature deposition performance of the lubricating oil composition for internal combustion engines is good. In addition, it can be seen that since MoDTC is formulated at a high concentration, it is excellent in fuel economy.

On the other hand, it can be seen that in Comparative Example 2 and Comparative Example 3 where the value of 0.5×P+Mo is greater than 0.075, the quality of the deposit is large and the high-temperature deposition performance is poor. In addition, in Comparative Example 4 without MoDTC, although the value of 0.5×P+Mo is small and the high-temperature deposition performance is excellent, the fuel-saving performance is poor. In addition, although the value of 0.5×P+Mo is small in Comparative Example 5 without ZnDTP, the high-temperature deposition performance is excellent, but the abrasion resistance performance is poor.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, can use the technical content disclosed above to make some changes or modify equivalent embodiments with equivalent changes, but all the content that does not depart from the technical solution of the present invention, according to the present invention Any simple modifications, equivalent changes and modifications made to the above embodiments by the technical essence still belong to the scope of the technical solution of the present invention.

Claims (5)

1. A lubricating oil composition for an internal combustion engine, characterized in that, in mineral oil and/or synthetic base oil, 0.12% by mass to 0.24% by mass of an alkaline earth metal-based detergent in terms of metal components, and A phosphorus-based additive containing at least 0.005% to 0.070% by mass of phosphorus as a phosphorus component and 0.030 to 0.075% by mass of molybdenum dithiocarbamate as a molybdenum component. and the phosphorus component of the phosphorus-based additive and the molybdenum component of the molybdenum dithiocarbamate meet the conditions represented by the following formula (1): 0.5×P+Mo≤0.075 (1) In the formula, P represents the ratio by mass % of the phosphorus component of the phosphorus-based additive in the lubricating oil composition, and Mo represents the ratio by mass % of the molybdenum component of the molybdenum dithiocarbamate in the lubricating oil composition. 2. The lubricating oil composition for an internal combustion engine according to claim 1, characterized by containing the molybdenum dithiocarbamate in an amount of 0.045% by mass to 0.075% by mass as a molybdenum component. 3. The lubricating oil composition for an internal combustion engine according to claim 1, characterized by containing the phosphorus-based additive in an amount of 0.005 mass% to 0.050 mass% in terms of phosphorus component. 4. The lubricating oil composition for an internal combustion engine according to claim 1, characterized by containing the alkaline earth metal-based detergent in an amount of 0.15% by mass to 0.20% by mass as a metal component. 5. The lubricating oil composition for internal combustion engines according to claim 1, characterized in that the kinematic viscosity of the base oil at 100°C is 3.5 mm ² /s-5.0 mm ² /s, and the viscosity index is 110-160 .