Euro VI (China VI) Engine Oil Composition for Improving Rubber Compatibility and Preparation Method

Abstract

The present invention relates to an Euro VI (China VI) engine oil composition for improving rubber compatibility and a preparation method thereof. It comprises the following components in parts by weight: 10.0 - 20.0 parts of a composite additive, 60.0 - 80.0 parts of a base oil, 3.0 - 8.0 parts of a viscosity index improver, and 0.1 - 1.0 part of a pour point depressant; the composite additive is a mixture of a detergent, a dispersant, an extreme pressure anti-wear agent, an antioxidant, a friction improver, and a rubber compatibility improver; the rubber compatibility improver is a polyisobutylene succinic anhydride derivative, and the average relative molecular weight of the polyisobutylene succinic anhydride derivative is 1000 - 1300; the dispersant is a boronated ashless dispersant and a non-boronated ashless dispersant. The oil composition of the present invention has good rubber compatibility, emission performance, and energy-saving performance, and is used for engine lubrication in harsh environments, and is suitable for other types of light-duty Euro VI or China VI engines with special requirements for the energy-saving performance, emission performance, and rubber compatibility of engine oils.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating oils, and particularly to an Euro VI / China VI engine oil composition for improving rubber compatibility and a preparation method thereof. Background Art

[0002] In the automotive industry, especially in light vehicles, the requirements for energy conservation and emission reduction are becoming increasingly stringent. To meet the technical requirements of stringent fuel economy and pollutant emission performance, in addition to upgrading engine technology, European OEM vehicle manufacturers also put forward more performance requirements for the matching lubricating oils, including fuel economy, emission performance, and rubber compatibility, etc.

[0003] Engine oil is a lubricating oil used to lubricate the metal moving parts of an engine, and plays roles such as lubrication, cooling, and sealing for the engine. Rubber materials are high-elastic polymer compounds and are used in the engine system as sealing gaskets, O-ring seals, rubber drive belts, valve stem oil seals, etc. Common rubber materials in automotive engines include fluoroelastomer (FKM), ethylene propylene rubber (AEM), hydrogenated nitrile rubber (HNBR), etc.

[0004] The compatibility between engine oil and rubber means that when the engine is working, the engine oil has no erosion ability on the rubber parts it contacts, and the rubber parts will not contaminate the lubricating oil they contact either.

[0005] In order to meet requirements such as the fuel economy of engine oil, the types of additives in energy-saving engine oils are increasing, and the dosage levels of additives are getting higher. However, high-dose additive formulations also bring problems of rubber compatibility, that is, some sulfur-containing additives in the oil have a certain erosion risk to rubber materials under high-temperature working conditions.

[0006] Although Euro VI engine oil products have emerged on the market currently, due to the influence of existing means to improve fuel economy on their rubber compatibility, most current products are difficult to have good rubber compatibility, emission performance, and energy-saving performance at the same time, and thus are difficult to meet the lubrication and sealing requirements of the engine under long-term high-temperature working conditions. Therefore, there is an urgent need in the art for an Euro VI / China VI engine oil product for improving rubber compatibility. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides an Euro VI or China VI engine oil composition for improving rubber compatibility, and a preparation method and application thereof. The Euro VI engine oil composition for improving rubber compatibility provided by the present invention effectively overcomes the defect that existing engine oil products are difficult to simultaneously meet the requirements of rubber compatibility, emission performance and energy-saving performance. This engine oil composition can take into account good rubber compatibility, emission performance and energy-saving performance, and can be used for engine lubrication under relatively harsh environments (such as long-term high-temperature working conditions).

[0008] In the research process, the inventors of the present invention found that in the prior art, engine oil usually uses 100N and / or 150N base oils, and is compounded with multifunctional compound additives, viscosity index improvers, friction improvers, and pour point depressants to improve energy-saving performance and emission performance. However, this compounding method cannot take into account the long-term rubber compatibility, and thus it is difficult to meet the sealing performance under long-term high-temperature working conditions. Reducing additives such as sulfur can improve the rubber compatibility of engine oil, but it will cause a significant decline in other properties (such as anti-wear performance, etc.).

[0009] The present invention provides an Euro VI / China VI engine oil composition for improving rubber compatibility, which comprises the following components in parts by weight: 10.0 - 20.0 parts of compound additives, 60.0 - 80.0 parts of base oil, 3.0 - 8.0 parts of viscosity index improver, and 0.1 - 1.0 part of pour point depressant; the compound additives are a mixture of detergents, dispersants, extreme pressure anti-wear agents, antioxidants, friction improvers, and rubber compatibility improvers; the rubber compatibility improver is polyisobutylene succinic anhydride derivative (PIBSA), and the average relative molecular weight of the polyisobutylene succinic anhydride derivative is 1000 - 1300; the dispersant is borated ashless dispersant and non-borated ashless dispersant.

[0010] Aiming at the problems existing in the existing engine oil, the present invention proposes to reinforce the formulation by adding a rubber compatibility improver in order to improve the long-term rubber compatibility of the engine oil. However, since the engine oil formulation system usually contains free low-molecular-weight polar compounds, which have a certain corrosive effect on certain types of rubbers (especially fluororubbers), the compounded composition still cannot solve the problem of rubber compatibility only by directly adding a rubber reinforcing agent technology. Therefore, the present invention further studies and finds that by using a compound additive with a specific composition, especially by using a borated dispersant and a non-borated dispersant, and mixing with a rubber compatibility improver, it has good formulation balance and compatibility, and solves the above problems; the obtained oil composition can excellently meet the requirements of automobile manufacturers for the rubber compatibility, energy-saving performance and emission performance of the supporting engine oil, so as to meet the engine lubrication and sealing requirements under long-term high-temperature working conditions.

[0011] The average relative molecular weight of the polyisobutylene succinic anhydride derivative is 1000 to 1300 and has the following general structural formula:

[0012]

[0013] Preferably, the PIBSA is selected from the mixture of Yangzi Petrochemical PIBSA1000 and PIBSA1300 or one of them, and the mass ratio is (0 to 1):(0 to 1).

[0014] In the present invention, the PIBSA is prepared by an existing thermal addition process.

[0015] Preferably, the dispersant in the compounding agent is a boronized ashless dispersant and a non-boronized ashless dispersant, and their mass ratio is (0.1 to 3):(0.4 to 7). The non-boronized ashless dispersant is selected from two or more of isobutylene succinimide, polyisobutylene succinate, ashless phosphonate or benzylamine, and preferably, the mass ratio of isobutylene succinimide and polyisobutylene succinate is 0.4 to 4:0 to 3. Further preferably, the non-boronized ashless dispersant is composed of polyisobutenyl succinimide (T161) and diallyl succinimide (T154) in a mass ratio of 3:1.

[0016] Preferably, the mass ratio of the detergent, dispersant, extreme pressure anti-wear agent, antioxidant, friction modifier, and rubber compatibility improver is (0.5 to 10):(0.5 to 10):(0.5 to 8)(0.1 to 3):(0.1 to 2):(0.1 to 1).

[0017] Preferably, the base oil is an HVI III+ type base oil or a mixture of an HVI III type base oil and a PAO base oil; preferably, the kinematic viscosity of the base oil at 100 °C is 4.0 to 4.4 mm 2 / s and the viscosity index ≥ 125, the evaporation loss (Noack method) is not higher than 13% by mass fraction, and the aniline point is not lower than 120 °C.

[0018] Preferably, the pour point depressant is selected from acrylate high molecular polymers.

[0019] Preferably, the friction modifier is at least one of molybdenum dialkyldithiocarbamate and its derivatives; preferably, the molybdenum dialkyldithiocarbamate and its derivatives are a mixture of binary molybdenum and ternary molybdenum, and their ratio is (0.1 to 0.5):(0.1 to 1).

[0020] More preferably, the rubber compatibility improver is selected from PIBSA1000 and / or PIBSA1300; the detergent is selected from calcium alkyl salicylate and / or magnesium alkyl salicylate; the dispersant is selected from borated ashless dispersant and non-borated ashless dispersant; the extreme pressure and anti-wear agent is selected from one or more of zinc dialkyldithiophosphate, sulfur-phosphorus mixed primary and secondary alkyl zinc salts and sulfurized olefins; the antioxidant is selected from octyldibutylaniline and / or high molecular weight alkylphenol. Using the above preferred additives can better exert the compatibility and synergy of each component, and the comprehensive performance of the engine oil is better.

[0021] Preferably, the viscosity index improver is a comb-shaped polymethacrylate type improver (PMA) and / or a comb-shaped polyacrylate type improver, and the shear stability index (SSI) is not greater than 5. Under this preferred scheme, the compatibility and synergy between various raw materials can be fully exerted.

[0022] Preferably, the comb-shaped polymethacrylate type improver (PMA) has the following general structural formula:

[0023]

[0024] Note: In the formula, R is a hydrocarbon group of C1-C20, preferably a hydrocarbon group of C3-C15.

[0025] Preferably, the hydrocarbon group can be a saturated or unsaturated alkyl group, or a branched or straight-chain hydrocarbon group, and can be at least one of isobutyl, isodecyl, and tridecyl.

[0026] Preferably, the above-mentioned comb-shaped PMA is a commercially available product, such as products produced by Sanyo Chemical Industries, Ltd. in Japan, Lubrizol Corporation in the United States, Evonik Industries AG in Germany, etc.; specifically, it can be at least one of Aclube V7030, Lubrizol VL9101F, and Viscoplex3-201.

[0027] In the present invention, the shear stability index (SSI) is measured by SH / T 0103-2007 and GB / T 265-1988; specifically, the sample is sheared by the method of SH / T 0103-2007, and then the viscosities before and after shearing are measured by the method of GB / T 265-1988, and then the SSI is calculated.

[0028] As a preferred embodiment of the present invention, the Euro VI / China VI engine oil for improving rubber compatibility comprises the following components in parts by weight: the compound additive is 13-18 parts, the base oil is 76-83 parts, the viscosity index improver is 4-5 parts, and the pour point depressant is 0.1-0.5 parts.

[0029] Further preferably, the Euro VI / China VI engine oil for improving rubber compatibility comprises the following components in parts by weight: 16.1 parts of a compound agent, 79.1 parts of a base oil, 4.5 parts of a viscosity index improver, and 0.3 parts of a pour point depressant.

[0030] Preferably, based on the total amount of the engine oil compound agent, as determined by ASTM D5185, the boron content in the compound agent is ≥0.13% by weight, the calcium content is ≤0.86% by weight, and the magnesium content is ≤0.35% by weight.

[0031] The Euro VI / China VI engine oil for improving rubber compatibility according to the present invention can be prepared by the processes disclosed in the prior art. To ensure and enhance the effect of the engine oil, the present invention provides a preferred preparation method, comprising the following steps:

[0032] (1) Mix the base oil, the viscosity index improver, and the pour point depressant to obtain a homogeneous liquid I;

[0033] (2) Mix the obtained homogeneous liquid I with the compound agent to obtain the engine oil.

[0034] Further preferably, the mixing temperature in step (1) is 50 - 60°C.

[0035] Further preferably, the mixing temperature in step (2) is 55 - 60°C.

[0036] The Euro VI / China VI engine oil composition for improving rubber compatibility prepared by the preparation method provided by the present invention can meet the ACEA C5 specification, including but not limited to 0W-20 lubricating oil, with a sulfur content of not more than 0.3% (mass fraction), a phosphorus content of not more than 0.08% (mass fraction), and a sulfate ash content of not more than 0.8% (mass fraction), and is a low-sulfur, low-phosphorus, and low-ash Euro VI engine oil.

[0037] The Euro VI / China VI engine oil composition for improving rubber compatibility of the present invention has a wide range of applications, and is particularly suitable for other types of light-duty Euro VI or China VI engines with special requirements for the energy-saving performance, emission performance, and rubber compatibility of the engine oil. It is preferably applied in light-duty engines using FKM, AEM, and HNBR type rubber seals.

[0038] The beneficial effects of the present invention are at least as follows: The technical solution of the present invention using various raw materials of specific types and dosages can give full play to the compatibility, and further improve the rubber compatibility, energy-saving performance, and emission performance of the prepared Euro VI / China VI engine oil composition for improving rubber compatibility, solving the technical problem that engine oil cannot meet the requirements of OEM manufacturers for the rubber compatibility of oil products. The basic physical and chemical data of the prepared engine oil composition are shown in Table 1. The selected high-performance additive formulation system can effectively improve the rubber compatibility, energy-saving performance, and emission performance of the oil product. After a certain OEM rubber compatibility test (1000 h), the rubber compatibility index of the engine oil composition has been significantly improved compared with the existing reference oil. After verification by the energy-saving bench test and the emission performance bench test, its comprehensive performance of energy-saving and emission performance is significantly better than that of similar products in the market.

[0039] Table 1 Basic physical and chemical data of the Euro VI / China VI engine oil for improving rubber compatibility of the present invention

[0040]

[0041] Detailed implementation manners

[0042] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following describes in detail the specific implementation manners, features, and effects of the engine oil according to the present invention in combination with preferred embodiments. The following embodiments are used to illustrate the present invention, but not to limit the scope of the present invention. For those not specifying specific techniques or conditions in the embodiments, they shall be carried out according to the techniques or conditions described in the literature in the field or according to the product specifications. For those reagents or instruments not indicating the manufacturer, they are all conventional products that can be obtained through regular channels.

[0043] The present invention will be described in detail below through embodiments. In the following Embodiments 1-5, the specific formulation of the compound agent in the engine oil is as follows: the mass ratio of the detergent, dispersant, extreme pressure and anti-wear agent, antioxidant, friction modifier, and rubber compatibility improver is 6:7:0.8:1.2:1:0.5. Among them: the rubber compatibility improver is PIBSA1300; the dispersant is composed of a borated ashless dispersant and a non-borated ashless dispersant in a mass ratio of 1:6; the borated ashless dispersant is borated high molecular weight succinimide (T161B); the non-borated ashless dispersant is composed of polyisobutenyl succinimide (T161) and diallyl succinimide (T154) in a mass ratio of 3:1; the detergent is composed of calcium alkyl salicylate and magnesium alkyl salicylate in a mass ratio of 4:1. The extreme pressure and anti-wear agent is composed of sulfurized olefins, zinc dialkyldithiophosphate, and sulfur-phosphorus mixed primary and secondary alkyl zinc salts in a mass ratio of 1:3:3. The antioxidant is composed of octyldiphenylamine and high molecular weight alkylphenol in a mass ratio of 5:1. The friction modifier is at least one of molybdenum dialkyldithiocarbamate and its derivatives; preferably, the friction modifier is composed of binary molybdenum and ternary molybdenum of the molybdenum dialkyldithiocarbamate derivative in a mass ratio of 7:3. The above compound agent satisfies: the boron content measured according to ASTM D5185 ≥ 0.13% by weight, the calcium content ≤ 0.86% by weight, and the magnesium content ≤ 0.35% by weight.

[0044] Example 1

[0045] This example provides a preparation method of an Euro VI / China VI engine oil composition for improving rubber compatibility and the engine oil composition.

[0046] The Euro VI / China VI engine oil composition for improving rubber compatibility provided in this example, by weight, includes 16.1 parts of compound agent, 79.1 parts of base oil, 4.5 parts of viscosity index improver, and 0.3 part of pour point depressant. Among them, the base oil uses Sinopec HVI III4 and Sinopec PAO4, with a mass ratio of 2:1, and the kinematic viscosities at 100 °C are 4.37 mm 2 / s and 4.12 mm 2 / s, the viscosity indexes are 125 and 127 respectively, the evaporation loss (Noack method) are 12.6% and 11.8% respectively, and the aniline points are 126 °C and 121 °C respectively; the viscosity index improver uses Viscoplex3-201 of Evonik company, and the shear stability index (SSI) is 5; the pour point depressant uses Viscoplex1-300 of Evonik company.

[0047] Preparation method: Sequentially add the raw material base oil, viscosity index improver, and pour point depressant into a blending kettle, then start stirring and heat up to 45 - 50 °C, stir for 15 - 20 min to obtain homogeneous liquid I. Subsequently, add the compounding agent to homogeneous liquid I and make it at 50 - 60 °C with stirring for 60 - 80 min.

[0048] Example 2

[0049] This example provides a preparation method of an Euro VI / China VI engine oil composition for improving rubber compatibility and the engine oil composition.

[0050] The Euro VI / China VI engine oil composition for improving rubber compatibility provided in this example, by weight, includes 16.3 parts of compounding agent, 78.9 parts of base oil, 4.5 parts of viscosity index improver, and 0.3 part of pour point depressant. Among them, the base oil uses Sinopec HVI III4 and Sinopec PAO4 with a mass ratio of 2:1, the kinematic viscosities at 100 °C are 4.33 mm 2 / s and 4.05 mm 2 / s respectively, the viscosity indexes are 125 and 128 respectively, the evaporation losses (Noack method) are 12.8% and 11.8% respectively, and the aniline points are 125 °C and 120.5 °C respectively; the viscosity index improver uses Viscoplex3 - 201 from Evonik with a shear stability index (SSI) of 5; the pour point depressant uses Viscoplex1 - 318 from Evonik.

[0051] Preparation method: Sequentially add the raw material base oil, viscosity index improver, and pour point depressant into a blending kettle, then start stirring and heat up to 45 - 50 °C, stir for 15 - 20 min to obtain homogeneous liquid I. Subsequently, add the compounding agent to homogeneous liquid I and make it at 50 - 55 °C with stirring for 60 - 80 min.

[0052] Example 3

[0053] This example provides a preparation method of an Euro VI / China VI engine oil composition for improving rubber compatibility and the engine oil composition.

[0054] Carry out in a similar method to Example 1, the difference is that in this example, the dosages of each component in the engine oil are: 16.5 parts of compounding agent, 78.9 parts of base oil, 4.3 parts of viscosity index improver, and 0.3 part of pour point depressant. Among them, the base oil uses Sinopec HVI III4 and Sinopec PAO4 with a mass ratio of 2:1, the kinematic viscosities at 100 °C are 4.33 mm 2 / s and 4.05 mm 2 / s, the viscosity indices are 125 and 128 respectively, the evaporation losses (Noack method) are 12.8% and 11.8% respectively, and the aniline points are 125°C and 120.5°C respectively; the viscosity index improver uses VL9101F from Lubrizol Corporation, and the shear stability index (SSI) is 5; the pour point depressant uses Viscoplex1-318 from Evonik Corporation.

[0055] Example 4

[0056] This example provides a preparation method of an Euro VI / China VI engine oil composition for improving rubber compatibility and the engine oil composition.

[0057] It is carried out in a similar method to Example 1. The difference is that in this example, the dosages of each component in the engine oil are as follows: 16.4 parts of the compound additive, 79 parts of the base oil, 4.2 parts of the viscosity index improver, and 0.4 part of the pour point depressant. Among them, the base oil uses SINOPEC HVI III4 and SINOPEC PAO4, with a mass ratio of 1:1, and the kinematic viscosities at 100°C are 4.37 mm 2 / s and 4.12 mm 2 / s, the viscosity indices are 125 and 127 respectively, the evaporation losses (Noack method) are 12.6% and 11.8% respectively, and the aniline points are 126°C and 121°C respectively; the viscosity index improver uses Viscoplex3-201 from Evonik Corporation, and the shear stability index (SSI) is 5; the pour point depressant uses Viscoplex1-300 from Evonik Corporation.

[0058] Example 5

[0059] This example provides a preparation method of an Euro VI / China VI engine oil composition for improving rubber compatibility and the engine oil composition.

[0060] It is carried out in a similar method to Example 1. The difference is that in this example, the dosages of each component in the engine oil are as follows: 16.6 parts of the compound additive, 78.8 parts of the base oil, 4.1 parts of the viscosity index improver, and 0.5 part of the pour point depressant. Among them, the base oil uses SINOPEC HVI III4 and SINOPEC PAO4, with a mass ratio of 1:1, and the kinematic viscosities at 100°C are 4.33 mm 2 / s and 4.05 mm 2 / s, the viscosity indices are 125 and 128 respectively, the evaporation losses (Noack method) are 12.8% and 11.8% respectively, and the aniline points are 125°C and 120.5°C respectively; the viscosity index improver uses VL9101F from Lubrizol Corporation, and the shear stability index (SSI) is 5; the pour point depressant uses Viscoplex1-318 from Evonik Corporation.

[0061] To further verify the Euro VI engine oil obtained in the present invention for improving rubber compatibility, the inventor further carried out relevant verification experiments. Due to space limitations, only the most representative experimental examples are listed here.

[0062] Experimental Example 1

[0063] 1 Experimental Verification

[0064] Experimental Object:

[0065] Experimental Group 1: Tests 1 - 5 are respectively the Euro VI engine oils obtained in Examples 1 - 5 of the present invention for improving rubber compatibility;

[0066] Control Group 1: Compared with Example 1, the difference is only that the oil used in this control group does not contain borated dispersant and rubber compatibility improver.

[0067] Control Group 2: Compared with Example 1, the difference is only that the oil used in this control group contains rubber compatibility improver (PIBSA), but does not contain borated dispersant.

[0068] 2 Rubber Compatibility Test

[0069] Referring to the CECL - 112 - 16 rubber compatibility test method, two types of fluororubbers (model: Freudenberg75FKM595, Freudenberg 80FKM260519), ethylene - propylene rubber (model: Freudenberg AEM8540), and hydrogenated nitrile - butadiene rubber (model: Freudenberg 70HNBR248231) were soaked in the test oil under high - temperature conditions for 1000h rubber aging test, and six parameters including volume change rate (ISO 2781), IRDH hardness change (ISO48), tensile strength change rate (ISO37), elongation at break change rate (ISO 37), and compression set (ISO815 - 1 B / B) of the aged rubber were measured. The tests were carried out separately, and the results are shown in Table 2. The indicators in Table 2 are the quality index requirements of a certain OEM.

[0070] Table 2 Results of Rubber Compatibility Test

[0071]

[0072]

[0073] From the rubber compatibility results of Examples 1-5 of the experimental group and the control group in Table 2, it can be seen that the oils of Control Group 1 and Control Group 2 did not pass the compatibility tests of two types of fluororubbers FKM. However, for Examples 1-5 of the experimental group using the specific raw materials preferred in the present invention, they can all meet the technical index requirements of a certain OEM for the compatibility tests of four types of rubbers. In particular, the test results of the two types of fluororubbers FKM are significantly better than those of the control group, indicating that the engine oil described in the present invention has good rubber compatibility.

[0074] To further verify the Euro VI / China VI engine oil obtained in the present invention for its compatibility with rubber, the inventor further carried out relevant verification tests and achieved good experimental results. Due to space limitations, they will not be elaborated here one by one.

Claims

1. An Euro VI / China VI engine oil composition for improving rubber compatibility, characterized in that, It consists of the following components in parts by weight: 10.0 - 20.0 parts of a compound agent, 60.0 - 80.0 parts of a base oil, 3.0 - 8.0 parts of a viscosity index improver, and 0.1 - 1.0 part of a pour point depressant; the base oil is a mixture of HVI Group III base oil and PAO base oil; the viscosity index improver is a comb-shaped polymethacrylate type improver and / or a comb-shaped polyacrylate type improver; the compound agent is a mixture of a detergent, a dispersant, an extreme pressure and anti-wear agent, an antioxidant, a friction improver, and a rubber compatibility improver; the rubber compatibility improver is PIBSA1000 and / or PIBSA1300; the dispersant is a borated ashless dispersant and a non-borated ashless dispersant; the non-borated ashless dispersant is polyisobutenyl succinimide and diallyl succinimide; the extreme pressure and anti-wear agent is selected from one or more of zinc dialkyldithiophosphate, sulfur-phosphorus mixed primary and secondary alkyl zinc salts, and sulfurized olefins; the antioxidant is selected from octyldibutylamine and / or high molecular weight alkylphenol; the borated ashless dispersant is borated high molecular weight succinimide; based on the total amount of the engine oil compound agent, measured according to ASTM D5185, the boron content in the compound agent is ≥ 0.13% by weight, the calcium content is ≤ 0.86% by weight, and the magnesium content is ≤ 0.35% by weight; the rubber is of the FKM, AEM, or HNBR type rubber.

2. The Euro VI / China VI engine oil composition for improving rubber compatibility according to claim 1, characterized in that, The mass ratio of the borated ashless dispersant to the non-borated ashless dispersant is (0.1 - 3):(0.4 - 7).

3. The Euro VI / China VI engine oil composition for improving rubber compatibility according to claim 1, characterized in that, In the compound agent, the mass ratio of the detergent, the dispersant, the extreme pressure and anti-wear agent, the antioxidant, the friction improver, and the rubber compatibility improver is (0.5 - 10):(0.5 - 10):(0.5 - 8):(0.1 - 3):(0.1 - 2):(0.1 - 1).

4. The Euro VI / China VI engine oil composition for improving rubber compatibility according to claim 1, characterized in that, The friction improver is selected from at least one of molybdenum dialkyldithiocarbamate and its derivatives.

5. The Euro VI / China VI engine oil composition for improving rubber compatibility according to claim 4, characterized in that, The molybdenum dialkyldithiocarbamate and its derivatives are a mixture of binary molybdenum and ternary molybdenum, and their mass ratio is (0.1 - 0.5):(0.1 - 1).

6. The Euro VI / China VI engine oil composition for improving rubber compatibility according to claim 5, characterized in that, The kinematic viscosity of the base oil at 100 °C is 4.0 to 4.4 mm 2 / s, the viscosity index ≥ 125, the evaporation loss is not higher than 13% by mass fraction, and the aniline point is not lower than 120 °C; The shear stability index of the viscosity index improver is not greater than 5.

7. The Euro VI / China VI engine oil composition for improving rubber compatibility according to claim 6, characterized in that, It consists of the following components in parts by weight: 13 - 18 parts of the compound agent, 76 - 80 parts of the base oil, 4 - 5 parts of the viscosity index improver, and 0.1 - 0.5 part of the pour point depressant.

8. A method for preparing the Euro VI / China VI engine oil composition for improving rubber compatibility according to any one of claims 1-7, characterized in that, It includes: 1) Mix the base oil, the viscosity index improver, and the pour point depressant to obtain a homogeneous liquid I; 2) Mix the obtained homogeneous liquid I with the compound agent to obtain engine oil.

9. The method for preparing an Euro VI / China VI engine oil composition for improving rubber compatibility according to claim 8, characterized in that, In step 1), the mixing temperature is 50 - 60 °C; in step 2), the mixing temperature is 55 - 60 °C.

10. The engine oil composition according to any one of claims 1 - 7 is applied in an Euro VI or China VI light-duty engine.

11. The application according to claim 10, characterized in that, It is applied in a light-duty engine using FKM, AEM, or HNBR type rubber seals.

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