Alcohol-resistant low viscosity lubricating oil composition and use thereof

Abstract

Alcohol-resistant, low-viscosity lubricating oil composition and its use. The components of the lubricating oil composition include: 0.6-1.0% of a metal detergent, 6.0-10.0% of an ashless dispersant, 0.5-2.0% of an antioxidant anti-wear agent, 1.0-2.0% of a metal deactivator, 0.2-1.0% of a high-pressure anti-wear agent, 3.0-5.0% of a viscosity index improver, 0.1-0.2% of a pour point depressant, 0.001-0.010% of an antifoaming agent, and 30.0-50.0% of a CTL base oil, the remainder being an API Group III base oil. The lubricating oil composition exhibits good wear resistance and good cold-start properties at low temperatures.

Description

field of technology

[0001] The present invention is classified in the technical field of lubricating oil and relates in particular to a lubricating oil composition with a performance that meets the lubrication requirements of a passenger car M100 methanol engine. State of the art

[0002] Currently, the viscosity grade of an oil product for methanol engines in M100 passenger cars is 5W-30. With the increasing use of oil for methanol engines, oil used in cold regions during winter (-36°C) exhibits poor cold-start performance (failing to start within 5 seconds) and high start-up wear (poor oil flow, preventing it from reaching the surface of parts in time to provide lubrication). To simultaneously meet the need for further increases in mileage before an oil change, higher demands are being placed on the wear protection properties of the oil product. Summary of the invention

[0003] To solve the above problems, one object of the present invention is to provide and use an alcohol-resistant, low-viscosity lubricating oil composition, wherein the lubricating oil composition has excellent wear resistance and excellent cold-start properties at low temperatures.

[0004] To solve the above problem, the present invention systematically investigates various types of additives and different types of base oils in the lubricating oil composition, and the interactions and relationships between the components are also comprehensively and systematically investigated. The wear resistance of the oil presents a major challenge that must be overcome, and by effectively combining a base oil with a high-pressure anti-wear agent, an antioxidant and anti-wear agent, a metal deactivator, and the like, the problem of deterioration of the anti-wear properties of lubricating oil in the presence of methanol, formic acid, and water, and the problem of poor cold-start properties of a methanol engine at low temperatures, have been successfully solved.

[0005] The present invention provides an alcohol-resistant, low-viscosity lubricating oil composition comprising: 0.6-1.0% of a metal detergent (component A), 6.0-10.0% of an ashless dispersant (component B), 0.5-2.0% of an antioxidant and anti-wear agent (component C), 1.0-2.0% of a metal deactivator (component D), 0.2-1.0% of a high-pressure anti-wear agent (component E), 3.0-5.0% of a tackifier (component F, also referred to as a viscosity regulator), 0.1-0.2% of a pour point depressant (component G), 0.001-0.010% of an antifoaming agent (component H), 30.0-50.0% of a CTL base oil (component I), and the remainder an API Group III base oil (component J), based on 100% of the total mass of the lubricating oil composition. comprising; wherein the antioxidant and anti-wear agent comprises a basic zinc dithiophosphate, an ashless amine-based antioxidant and an ashless phenol-based antioxidant;the metal deactivator comprises a thiadiazole-based metal deactivator and a methylbenzotriazole-based metal deactivator; the high-pressure anti-wear agent comprises a thioether-based high-pressure anti-wear agent, wherein the basic zinc dithiophosphate in the antioxidant and anti-wear agent has a sulfur-to-phosphorus ratio of 1.8-1.9 and a zinc-to-phosphorus ratio of 1.1-1.2, and the thioether-based high-pressure anti-wear agent in the high-pressure anti-wear agent has a sulfur content of 14.0-15.0%.

[0006] According to a specific embodiment of the present invention, the basic zinc dithiophosphate is preferably a basic zinc di-n-octyldithiophosphate.

[0007] In the present invention, extensive investigations have been carried out on various types of antioxidants and anti-wear agents. One such antioxidant and anti-wear agent is a mixture of an ashless amine-based antioxidant, an ashless phenol-based antioxidant, and basic zinc dithiophosphate. Zinc dithiophosphate exhibits excellent antioxidant, anti-wear, and anti-corrosion properties. It is generally assumed that the antioxidant effect is achieved by scavenging radicals and decomposing hydroperoxides. Due to the characteristics of methanol fuels, the increase in water as a combustion product has a significant impact on the antioxidant and anti-wear properties of neutral zinc dithiophosphate.In laboratory tests, an alkaline zinc dithiophosphate, such as basic zinc di-n-octyldithiophosphate, showed improved system stability and anti-wear properties in the presence of water, alcohol, and acid. It also exhibited superior synergistic effects with an ashless amine-based and a ashless phenol-based antioxidant, making it particularly suitable for oils used in methane-powered engines. Ashless antioxidants can generate hydrogen atoms for peroxide radicals, thereby disrupting or preventing chain growth and producing stable, low-energy radicals. A synergistic effect also exists between the ashless antioxidants, with the phenol-based antioxidant showing a significant synergistic effect when used with the amine-based antioxidant because the phenol facilitates the regeneration of the aromatic amine.In the present invention, the antioxidant and anti-wear agent is added in an amount of 0.5-2.0% and preferably in a suitable range of 0.5-1.8%.

[0008] An oil product oxidizes and decomposes during its use due to the effects of oxygen, heat, and light. If the lubricating oil contains metals such as copper, iron, and the like, these metals, particularly metal ions, accelerate the oxidation rate of the oil product, generating acids, sludge, and deposits that cause corrosion and abrasion of the metal parts. To prevent the catalytic acceleration of the automatic oxidation of the lubricating oil by metal ions, the present invention involves a comprehensive screening and formulation of various types of metal deactivators. One metal deactivator is a mixture of a thiadiazole-based metal deactivator and a methylbenzotriazole-based metal deactivator.Benzotriazole is an inhibitor of iron-free copper and silver, can form a chelate with copper, and is an effective metal deactivator, despite its poor oil solubility. To improve oil solubility, a benzotriazole derivative is being developed that exhibits a marked synergistic effect when used in combination with a phenolic antioxidant (2,6-di-tert-butyl-p-cresol). The thiadiazole-based metal deactivator is a copper corrosion inhibitor and has the effect of scavenging active sulfur, thus playing a role in metal deactivation. It contains a disulfide bond and can form a vulcanization film on the metal surface, thereby inhibiting the metal's catalytic effect on the oxidation of petroleum products, significantly extending the oxidation lifetime, and improving hydrolysis resistance.In the present invention, the added metal deactivator is added in an amount of about 1.0-2.0%, based on the total weight of the lubricating oil composition.

[0009] To give the composition excellent wear protection properties, it is crucial to select from different types of wear inhibitors and their proportions in the formulation. For example, a sulfated olefin wear inhibitor exhibits high resistance to sintering stress and good heat resistance, but poor wear protection properties; a chlorinated paraffin has good wear protection and high-pressure properties and strong activity, but poor stability and is prone to corrosion and toxicity; with a phosphatamine salt wear inhibitor, the better the wear protection properties, the worse the heat resistance; like nanoparticles, they suffer from the problems of insufficient solubility and poor stability.In the present invention, the high-pressure anti-wear agent is a thioether-based high-pressure anti-wear agent (for example, dibenzyl disulfide, etc.) with a sulfur content of 14.0–15.0%. In the present application, an organic carboxylate based on thioethers can also be used as the high-pressure thioether-based anti-wear agent. Due to the highly polar ester group present in the ester-based oil molecules, the organic carboxylate based on thioethers exhibits good adsorption to an electron-rich metal surface, thereby facilitating the spread and maintenance of a lubricating oil film. It also exhibits outstanding anti-wear properties, good heat resistance, and low corrosion resistance, effectively solving the problem of failure of conventional anti-wear agents caused by methanol, formic acid, and water.In the present invention, the high-pressure wear protection agent is added in an amount of 0.2-1.0% and preferably in a suitable range of 0.2-0.8%.

[0010] According to a specific embodiment of the present invention, the antioxidant and anti-wear agent preferably comprises 40-60% of the basic zinc dithiophosphate, 20-30% of the ashless amine-based antioxidant, and 10-20% of the phenol-based antioxidant, based on 100% by mass of the antioxidant and anti-wear agent; and in the metal deactivator, the mass ratio of the thiadiazole-based metal deactivator to the methylbenzotriazole-based metal deactivator is 1:2-2:1.

[0011] According to a specific embodiment of the present invention, the lubricating oil composition preferably comprises: 0.7-1.0% of the metal detergent, 6.0-8.0% of the ashless dispersant, 0.5-1.8% of the antioxidant and anti-wear agent, 1.0-2.0% of the metal deactivator, 0.2-0.8% of the high-pressure anti-wear agent, 3.0-5.0% of the tackifier, 0.1-0.2% of the pour point reducer, 0.001-0.010% of the antifoaming agent, 30.0-40.0% of the CTL base oil and, as the remainder, an API Group III base oil (preferably 30-60%).

[0012] According to a specific embodiment of the present invention, the metal detergent preferably comprises a calcium salt and a magnesium salt.

[0013] According to a specific embodiment of the present invention, the calcium salt preferably comprises calcium salicylate and / or calcium sulfonate, and the magnesium salt comprises magnesium salicylate and / or magnesium sulfonate. Sulfonates are used in engine oil and can neutralize acidic oxides formed during engine operation and inhibit oxidative deterioration of the lubricating oil or reduce the formation of high-temperature deposits on the surface of a piston ring area under high-temperature conditions, thereby keeping the engine interior clean; at the same time, oil-insoluble colloids or oxides produced by oxidation of lubricating oil and incomplete combustion of fuel can be dissolved in the oil, thereby suppressing the tendency to form deposits such as varnish, carbon deposits, and oil sludge.In an alkyl salicylate, a carboxyl group is introduced into an alkylphenol, and metal is transferred from the hydroxyl group to where the carboxyl group is located. This transformation results in an alkyl salicylate with extremely high molecular polarity and greatly improves its high-temperature cleaning properties. This allows it to exhibit good high-temperature cleaning performance, as well as characteristics of dispersion at relatively low temperatures, oxidation resistance, corrosion resistance, high-pressure wear resistance, and good synergistic effect with other agents. A combination of different detergent types creates a synergistic effect of the additives, enabling good cleaning performance, rust resistance, and a low sulfated ash content. Furthermore, it ensures that the petroleum product has a certain base number to neutralize acidic substances.The metal detergent in the present invention comprises approximately 0.6–1.0% of the total weight of the composition, with a preferred range being 0.7–1.0%. If the amount used is too small, the result is a deterioration of the oil cleaning performance, a low base number, and a shortened service life of the lubricant; if the amount used is too large, the ash content in the lubricating oil may increase, thereby increasing the frequency of premature combustion at low engine speeds and affecting the functioning of other functional additives without any additional beneficial effects.

[0014] According to a specific embodiment of the present invention, the ashless dispersant preferably comprises polyisobutylene succinimide, more preferably a polymeric polyisobutylene succinimide with a high nitrogen content and a high base number, with a nitrogen content of 1.8–2.2% and a base number of 46–55 mg KOH / g. An ashless dispersant is a surfactant primarily used to disperse contaminants generated in an engine to ensure the free flow of oil. The dispersing properties of the ashless dispersant can help keep the engine clean and, in some cases, aid in maintaining piston cleanliness. Different types of dispersants exhibit varying dispersing effects on sludge and deposits.Polymer-based dispersants with high base numbers generally exhibit better dispersing effects on deposits formed at high temperatures, while dispersants with normal molar masses exhibit better dispersing effects on deposits formed at low temperatures. In the present invention, a polymeric polyisobutylene succinimide with a high nitrogen content and a high base number is used as an ashless dispersant. In addition to exhibiting better dispersing properties, it can also help to reduce the degradation of ZDDP performance, enhance the anti-wear effect of the high-pressure anti-wear agent, and increase the base number capacity of the engine oil. The ashless dispersant comprises approximately 6.0–10.0% of the total weight of the composition and is preferably present in a suitable range of 6.0–8.0%.If the amount used is too small, this results in a deterioration of the oil's dispersing performance, an increase in deposits on the surface of engine parts, and thicker oil sludge in the oil pan; if the amount used is too large, the additives are wasted and the effects of other functional additives in the lubricating oil are affected without any additional beneficial effects.

[0015] According to a specific embodiment of the present disclosure, the tackifier preferably comprises an ethylene-propylene copolymer, such as RHY615, 9230F, and the like. The properties of the lubricating oil are closely related to the type and shear strength of the tackifier. In the present invention, an ethylene-propylene copolymer with a shear index of 20 is preferably used as the tackifier. The tackifier of the present invention comprises about 3.0–5.0% of the total weight of the composition.If the amount used is too small, it results in lower viscosity, reduced film thickness and stability, and reduced wear protection properties in actual use; if the amount used is too large, the additives are wasted, increasing the oil viscosity and resulting in decreased low-temperature performance and cleaning performance, without any additional beneficial effects.

[0016] According to a specific embodiment of the present invention, the pour point depressant preferably comprises polymethacrylate. The addition of a pour point depressant can lower the pour point of lubricating oil to improve the performance of the oil product used in a low-temperature environment. In the present invention, the amount of pour point depressant added is not particularly limited and is generally 0.1–0.2% of the total mass of the lubricating oil composition. If the value is less than 0.1%, the amount used is too small, which may result in the pour point of the lubricating oil not meeting the requirements of the standard and affect its flowability in a low-temperature environment.

[0017] According to a specific embodiment of the present invention, the antifoaming agent preferably comprises dimethicone. An antifoaming agent can reduce the phenomenon of foam formation from mechanically agitated lubricating oil during actual use and prevent the problem of part of the oil film of an engine component tearing and wearing down due to a large amount of foam generated during operation. The amount of antifoaming agent added is not particularly limited and is generally 0.001–0.010% of the total mass of the lubricating oil composition. If the value is lower than 0.001%, the amount used is too small, resulting in a deterioration of the antifoaming resistance; if the value is higher than 0.010%, the amount used is too large, wasting the additives without any additional beneficial effects.

[0018] According to a specific embodiment of the present invention, the CTL base oil is a synthetic carbon oil with a kinematic viscosity at 100 °C of 3.8-4.2 mm. 2 / s, more strongly preferred 4 mm 2 / s.

[0019] According to a specific embodiment of the present invention, the API Group III base oil is an API Group III hydrocracking base oil with a kinematic viscosity at 100 °C of 3.8-4.3 mm. 2 / s, more strongly preferred 4 mm 2 / s.

[0020] According to a specific embodiment of the present invention, the lubricating oil composition preferably has a sulfur content of 0.20-0.30 wt.%, a phosphorus content of 0.06-0.07 wt.%, a base number of 9.0-11.0 mg KOH / g, and a sulfated ash content of 0.4-0.6 wt.%. At the end of a 120-hour endurance test of an M100 methanol engine according to NB / SH / T 0189, the lubricating oil composition exhibited a four-ball wear spot diameter of 0.8 mm or less, and the methanol engine started at -36 °C within 3.5 seconds.

[0021] According to a specific embodiment of the present invention, the above-mentioned base oil is a combination of two base oils with high viscosity indices that meet the requirements of the standard for API Group III base oils.

[0022] The present invention further makes the use of the lubricating oil composition available in a passenger car M100 methanol engine.

[0023] In the present invention, the major technical challenge based on the mechanism of action of the additives was solved through a systematic and comprehensive screening and formulation optimization of various additive types and additives of the same type with different compositions using various simultaneous tests. This was ultimately achieved through laboratory simulation tests and endurance tests of an M100 methanol engine. The synergistic effect among the additives was improved by introducing and adjusting the types and proportions of the additives. Compared to existing commercially available products, it exhibits better wear protection properties, improved cold-start properties at low temperatures, and meets the lubrication requirements of an M100 methanol engine.In the endurance test of an M100 methanol engine, it exhibits better wear resistance and better cold-start properties at low temperatures in a cold region, thus meeting the requirements for low viscosity and a long oil change interval for oil for methanol engines. Brief description of the drawings Fig. Figure 1 is a photograph of the pressure-bearing surface of a piston; Fig. Figure 2 is a photograph of the non-pressure-bearing surface of a piston; Fig. 3 is a photograph of the oil pan. Detailed description of the invention

[0024] To obtain a clearer understanding of the technical features, purposes and advantageous effects of the present invention, the technical solution of the present invention is now described in detail below, but should not be interpreted as limiting the implementable scope of the present invention.

[0025] In the present invention, the selection of base oils and additive components utilizes PDSC (induction duration), wear point diameter, dynamic low-temperature viscosity, and other laboratory test methods to assess the oxidation resistance, wear resistance, and low-temperature flowability of oil products. The test conditions for the simulations each included: a PDSC oxidation induction duration set to 210 °C, a template diameter of 392 N, and a dynamic low-temperature viscosity test at -35 °C. Example 1

[0026] In this example, a lubricating oil composition is made available, and the starting materials used per 100 kg of the composition and their masses are as follows: 0.5 kg calcium salicylate with a base number of 265-295; 0.5 kg magnesium sulfonate with a base number of 395-430; 8.0 kg polymeric polyisobutylene succinimide with a base number of 46 mgKOH / g and a nitrogen content of 1.8%; 0.9 kg basic zinc di-n-octyldithiophosphate with a sulfur to phosphorus ratio of 1.80 and a zinc to phosphorus ratio of 1.1; 1.0 kg of a mixture of p,p-diisooctyldiphenylamine and a hindered ester-based phenol (VANLUBE BHC) with a mass ratio of 1:1; 1.8 kg of a mixture of N,N-bis(2-ethylhexyl)methyl-1H-benzotriazol-1-methanamine and 2,5-dimercapto-1,3,4-thiadiazole with a mass ratio of 1:1; 0.8 kg of a dibenzyl disulfide anti-wear agent with a sulfur content of 14%; 4.0 kg of an ethylene-propylene copolymer tackifier (RHY615); 0.2 kg polymethacrylate; 0.005 kg of a dimethicone antifoaming agent; 40.0 kg of a CTL base oil with a viscosity at 100 °C of 3.8-4.2 mm 2 / s and 42.195 kg of a hydrogenated API Group III base oil with a viscosity at 100 °C of 3.8-4.3 mm 2 / s.

[0027] The lubricating oil composition in this example has a sulfur content of 0.28% and a phosphorus content of 0.067%. Example 2

[0028] In this example, a lubricating oil composition is made available, and the starting materials used per 100 kg of the composition and their masses are as follows: 0.5 kg calcium salicylate with a base number of 320-360; 0.5 kg magnesium alkyl salicylate with a base number of 400; 10.0 kg polymeric polyisobutylene succinimide with a base number of 48 mgKOH / g and a nitrogen content of 1.8%; 1.0 kg basic zinc di-n-octyldithiophosphate with a sulfur to phosphorus ratio of 1.9 and a zinc to phosphorus ratio of 1.1; 1.0 kg of a mixture of p,p-diisooctyldiphenylamine and a hindered ester-based phenol (VANLUBE BHC) with a mass ratio of 1:1; 2.0 kg of a mixture of N,N-bis(2-ethylhexyl)methyl-1H-benzotriazol-1-methanamine and 2,5-dimercapto-1,3,4-thiadiazole with a mass ratio of 1:1; 0.5 kg of a dibenzyl disulfide anti-wear agent with a sulfur content of 14%; 4.0 kg of an ethylene-propylene copolymer tackifier (9230F); 0.2 kg polymethacrylate; 0.005 kg of a dimethicone antifoaming agent; 40.0 kg of a CTL base oil with a viscosity at 100 °C of 3.8-4.2 mm 2 / s and 40.395 kg of a hydrogenated API Group III base oil with a viscosity at 100 °C of 3.8-4.3 mm 2 / s.

[0029] The lubricating oil composition in this example has a sulfur content of 0.27% and a phosphorus content of 0.070%. Example 3

[0030] In this example, a lubricating oil composition is made available, and the starting materials used per 100 kg of the composition and their masses are as follows: The components and masses are the same as in Example 2, except that the magnesium alkyl salicylate with a base number of 400 is replaced by magnesium sulfonate with a base number of 395-430.

[0031] The lubricating oil composition in this example has a sulfur content of 0.30% and a phosphorus content of 0.068%. Example 4

[0032] In this example, a lubricating oil composition is made available, and the starting materials used per 100 kg of the composition and their masses are as follows: 0.7 kg calcium salicylate with a base number of 265-295; 0.3 kg magnesium sulfonate with a base number of 395-430; 6.0 kg polymeric polyisobutylene succinimide with a base number of 47 mgKOH / g and a nitrogen content of 2.1%; 1.0 kg basic zinc di-n-octyldithiophosphate with a sulfur to phosphorus ratio of 1.8 and a zinc to phosphorus ratio of 1.1; 0.8 kg of a mixture of p,p-diisooctyldiphenylamine and a hindered ester-based phenol (VANLUBE BHC) with a mass ratio of 1:1; 1.0 kg of a mixture of N,N-bis(2-ethylhexyl)methyl-1H-benzotriazol-1-methanamine and 2,5-dimercapto-1,3,4-thiadiazole with a mass ratio of 1:1; 0.6 kg of a dibenzyl disulfide anti-wear agent with a sulfur content of 14%; 5.0 kg of an ethylene-propylene copolymer tackifier (RHY615); 0.2 kg polymethacrylate; 0.006 kg of a dimethicone antifoaming agent; 50.0 kg of a CTL base oil with a viscosity at 100 °C of 3.8-4.2 mm 2 / s; 34.394 kg of a hydrogenated API Group III base oil with a viscosity at 100 °C of 3.8-4.3 mm 2 / s.

[0033] The lubricating oil composition in this example has a sulfur content of 0.22% and a phosphorus content of 0.066%. Example 5

[0034] In this example, a lubricating oil composition is made available, and the starting materials used per 100 kg of the composition and their masses are as follows: 0.3 kg calcium salicylate with a base number of 320-360; 0.6 kg magnesium alkyl salicylate with a base number of 400; 7.0 kg polymeric polyisobutylene succinimide with a base number of 46 mgKOH / g and a nitrogen content of 1.8%; 1.0 kg basic zinc di-n-octyldithiophosphate with a sulfur to phosphorus ratio of 1.8 and a zinc to phosphorus ratio of 1.1; 1.0 kg of a mixture of p,p-diisooctyldiphenylamine and a hindered ester-based phenol (VANLUBE BHC) with a mass ratio of 1:1; 1.5 kg of a mixture of N,N-bis(2-ethylhexyl)methyl-1H-benzotriazol-1-methanamine and 2,5-dimercapto-1,3,4-thiadiazole with a mass ratio of 1:1; 0.8 kg of a dibenzyl disulfide anti-wear agent with a sulfur content of 14%; 4.0 kg of an ethylene-propylene copolymer tackifier (RHY615); 0.1 kg polymethacrylate; 0.005 kg of a dimethicone antifoaming agent; 45.0 kg of a CTL base oil with a viscosity at 100 °C of 3.8-4.2 mm 2 / s; 38.695 kg of a hydrogenated API Group III base oil with a viscosity at 100 °C of 3.8-4.3 mm 2 / s.

[0035] The lubricating oil composition in this example has a sulfur content of 0.26% and a phosphorus content of 0.071%. Comparative example 1

[0036] In this comparative example, a lubricating oil composition is made available, and the starting materials used per 100 kg of the composition and their masses are as follows: The components and masses are the same as in Example 1, except that the basic zinc di-n-octyldithiophosphate is replaced by a zinc secondary alkyldithiophosphate with a sulfur to phosphorus ratio of 2.1.

[0037] The lubricating oil composition in this example has a sulfur content of 0.35% and a phosphorus content of 0.080%. Comparative example 2

[0038] In this comparative example, a lubricating oil composition is made available, and the starting materials used per 100 kg of the composition and their masses are as follows: The components and masses are the same as in Example 1, except that the basic zinc di-n-octyldithiophosphate is replaced by a zinc secondary alkyldithiophosphate with a sulfur to phosphorus ratio of 2.1, and the polymeric polyisobutylene succinimide is replaced by a borated succinimide dispersant with a base number of 16.

[0039] The lubricating oil composition in this example has a sulfur content of 0.33% and a phosphorus content of 0.081%. Comparative example 3

[0040] In this comparative example, a lubricating oil composition is made available, and the starting materials used per 100 kg of the composition and their masses are as follows: The components and masses are the same as in Example 1, except that the CTL base oil is replaced by a hydrogenated API Group III base oil with a viscosity at 100 °C of 5.8–6.2 mm². 2 / s is replaced.

[0041] The lubricating oil composition in this example has a sulfur content of 0.28% and a phosphorus content of 0.070%.

[0042] To verify the effect of the present invention, performance was determined by laboratory simulations and a test on an engine test bench using the engine lubricating oils produced in the examples of the present invention, and the test results are shown in Table 1: 1. Determination of the laboratory performance of lubricating oil compositions Table 1. Results for determining the performance of lubricating oil compositions Points Example comparative example Commercially available 5W-30 methanol engine oil Test procedure 1 2 3 4 5 1 2 3 Base number / (mgKOH / g) 11,0 10,8 10,5 9,8 10,1 10,9 8,6 10,9 8,8 SH / T 0251 Sulphated ash content / in% by mass 0,54 0,52 0,52 0,58 0,54 0,54 0,52 0,53 0,65 GB / T 2433 PDSC (210 °C) / min 29,0 28,0 28,0 27 26 29,0 27,0 27,0 26,0 SH / T 0719 Wear point diameter (392 N) / mm, after addition of 0.2% methanol, 0.1% formic acid and 0.2% water in a specific ratio 0,58 0,57 0,60 0,63 0,61 0,82 Block 0,59 0,65 NB / SH / T0189 After a 120-hour endurance test on an M100 methanol engine (1.8 l / 100km) 0,78 / / / / / / / 0,88 (100 h) CCS (-35 °C) / mm 2 / s 4380 4650 4710 4120 4230 4460 5012 7320 5860(-30 °C) GB / T 6538

[0043] The data in Table 1 show that the lubricating oil of the present invention exhibits good oxidation and wear resistance during the induction period of PDSC oxidation and in the determination of the wear spot diameter in the simulation test. After a 120-hour endurance test on an M100 methanol engine, the wear spot diameter is 0.8 mm or less, which is better than that obtained from a 100-hour endurance test on a commercially available methanol oil. A dynamic low-temperature viscosity test at -35 °C demonstrates excellent low-temperature flow properties, and a low-temperature cold-start test within 5 seconds was performed with Example 1 on a methanol vehicle at an ambient temperature of -36 °C, achieving a start within 3.5 seconds.In Comparative Example 1 and Comparative Example 2, the anti-wear properties of all oils showed a significant decrease after mixing with water, methanol, and formic acid because no basic zinc dithiophosphate (basic zinc di-n-octyldithiophosphate) was used, although the PDSC properties of the engine oils were similar. Furthermore, in the case of Comparative Example 2, where no polymeric polyisobutylene succinimide with a high nitrogen content and a high base number was used, a serious consequence of blockage occurred in the wear test. In Comparative Example 3, where no CTL4 base oil was used, a significant reduction in the low-temperature flowability of the oil occurred, and the excellent low-temperature flowability of the present invention could not be achieved. 2. Inspection after disassembly of the lubricating oil composition of Example 1 after testing on the engine test bench

[0044] The lubricating oil composition of the present invention exhibited excellent properties of clean dispersion and excellent wear protection properties in the test on the methanol engine.

Claims

[1] Alcohol-resistant low-viscosity lubricating oil composition comprising: 0.6-1.0% of a metal detergent, 6.0-10.0% of an ashless dispersant, 0.5-2.0% of an antioxidant and anti-wear agent, 1.0-2.0% of a metal deactivator, 0.2-1.0% of a high-pressure anti-wear agent, 3.0-5.0% of a tackifier, 0.1-0.2% of a pour point depressant, 0.001-0.010% of an antifoaming agent, 30.0-50.0% of a CTL base oil and the remainder an API Group III base oil, based on 100% of the total mass of the lubricating oil composition; wherein the antioxidant and anti-wear agent comprises a basic zinc dithiophosphate, an ashless amine-based antioxidant and an ashless phenol-based antioxidant; the metal deactivator comprises a thiadiazole-based metal deactivator and a methylbenzotriazole-based metal deactivator; the high-pressure wear protection agent comprises a high-pressure wear protection agent based on thioethers; wherein the basic zinc dithiophosphate in the antioxidant and anti-wear agent has a sulfur to phosphorus ratio of 1.8-1.9 and a zinc to phosphorus ratio of 1.1-1.2 and The high-pressure wear protection agent based on thioethers has a sulfur content of 14.0-15.0%. [2] Lubricating oil composition according to claim 1, wherein the basic zinc dithiophosphate is a basic zinc di-n-octyldithiophosphate. [3] Lubricating oil composition according to claim 1 or 2, wherein the antioxidant and anti-wear agent comprises 40-60 wt% of basic zinc dithiophosphate, 20-30% of ashless amine-based antioxidant and 10-20% of ashless phenol-based antioxidant, based on 100 wt% of the antioxidant and anti-wear agent; and wherein in the metal deactivator the mass ratio of the thiadiazole-based metal deactivator to the methylbenzotriazole-based metal deactivator is 1:2-2:

1. [4] Lubricating oil composition according to claim 1, wherein the lubricating oil composition comprises: 0.7-1.0% of the metal detergent, 6.0-8.0% of the ashless dispersant, 0.5-1.8% of the antioxidant and anti-wear agent, 1.0-2.0% of the metal deactivator, 0.2-0.8% of the high-pressure anti-wear agent, 3.0-5.0% of the tackifier, 0.1-0.2% of the pour point depressant, 0.001-0.010% of the antifoaming agent, 30.0-40.0% of the CTL base oil and the remainder being the API Group III base oil. [5] Lubricating oil composition according to claim 1, wherein the metal detergent comprises a calcium salt and a magnesium salt. [6] Lubricating oil composition according to claim 5, wherein the calcium salt comprises calcium salicylate and / or calcium sulfonate and the magnesium salt comprises magnesium salicylate and / or magnesium sulfonate. [7] Lubricating oil composition according to claim 1, wherein the ash-free dispersing agent comprises polyisobutylene succinimide. [8] Lubricating oil composition according to claim 7, wherein the polyisobutylene succinimide has a nitrogen content of 1.8-2.2% and a base number of 46-55 mgKOH / g. [9] Lubricating oil composition according to claim 1, wherein the tackifier comprises an ethylene-propylene copolymer. [10] Lubricating oil composition according to claim 1, wherein the pour point reducer comprises a polymethacrylate. [11] Lubricating oil composition according to claim 1, wherein the antifoaming agent comprises dimethicone. [12] Lubricating oil composition according to claim 1, wherein the CTL base oil is a synthetic carbon oil with a kinematic viscosity at 100 °C of 3.8-4.2 mm 2 / s is involved. [13] Lubricating oil composition according to claim 1, wherein the API Group III base oil is an API Group III hydrocracking base oil with a kinematic viscosity at 100 °C of 3.8-4.3 mm 2 / s is involved. [14] Lubricating oil composition according to claim 1, wherein the lubricating oil composition has a sulfur content of 0.20-0.30 wt.%, a phosphorus content of 0.06-0.07 wt.%, a base number of 9.0-11.0 mgKOH / g and a sulfated ash content of 0.4-0.6 wt.% and the lubricating oil composition has a four-ball wear point diameter of 0.8 mm or less at the end of a 120-hour endurance test in an M100 methanol engine according to NB / SH / T 0189 and the methanol engine starts within 3.5 seconds at -36 °C. [15] Use of the lubricating oil composition according to any one of claims 1-14 in a passenger car M100 methanol engine.

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