KR20230025048A - Transmission oil composition for noise reduction and durability improvement - Google Patents

Abstract

The present invention relates to a transmission oil composition including: base oil; a metallocene-based resin; and a friction modifier including a phosphate ester-based compound, wherein the durability of a transmission can be improved while reducing noise generated from the transmission by mixing the metallocene-based resin and the friction modifier in a specific mixing ratio.

Description

Transmission oil composition for noise reduction and durability improvement {TRANSMISSION OIL COMPOSITION FOR NOISE REDUCTION AND DURABILITY IMPROVEMENT}

The present invention relates to an oil composition used in a transmission, and more particularly, to a transmission oil composition having improved noise reduction and durability by reducing the friction coefficient of manual transmission oil to an appropriate level.

Recently, regulations on vehicle exhaust gases such as carbon dioxide have become stricter in order to efficiently use energy and prevent global warming. Due to these environmental regulations, the development of fuel economy-enhancing engines and transmission oils that can reduce engine energy loss has been actively pursued.

In the conventional transmission oil, it was possible to improve the operability of gears and bearings and improve fuel efficiency by reducing loss generated during gear shifting by improving the friction coefficient, but noise increased in a specific field operation mode due to frictional resistance. On the other hand, if the friction coefficient of transmission oil is too low, wear and durability degradation due to slip may occur.

Therefore, it is necessary to develop a transmission oil composition capable of reducing the friction coefficient of the transmission oil to an appropriate level to solve the noise phenomenon and at the same time improve the durability of the transmission.

Republic of Korea Patent Publication No. 2008-0109877

The present invention is to solve the above problems, and an object of the present invention is to provide a transmission oil composition capable of improving durability of a transmission while reducing noise by reducing a friction coefficient to an appropriate level.

The object of the present invention is not limited to the object mentioned above. The objects of the present invention will become more apparent from the following description, and will be realized by the means and combinations described in the claims.

The transmission oil composition according to the present invention includes a friction modifier including a base oil, a metallocene-based resin, and a phosphoric acid ester-based compound.

The transmission oil composition may further include a viscosity modifier and an antiwear agent.

The transmission oil composition contains 75 to 85% by weight of the base oil, 2 to 6% by weight of the metallocene resin, 0.3 to 0.5% by weight of the friction modifier, 5 to 15% by weight of the viscosity modifier, and 3 to 5% by weight of the antiwear agent. can include

The base oil may include at least one selected from mineral oil, synthetic oil, and combinations thereof classified into groups 3 to 5 in the API (American Petroleum Institute) base oil category.

The metallocene-based resin may include polyalpha olefin (mPAO) polymerized with a metallocene catalyst.

A weight ratio of the metallocene-based resin and the friction modifier may be 4:1 to 20:1.

The friction modifier may be a compound represented by Formula 1 below.

[Formula 1]

(In Formula 1, the ratio of X and Y is 1:3 to 1:4, and the weight average molecular weight (Mw) is 200,000 g/mol to 400,000 g/mol.)

The viscosity modifier is polybutadiene hydrogen phosphate Comb Polymethacrylate (PHP Comb PMA), Comb Polymethacrylate (Comb PMA), esteric (Asteric), olefin copolymer ( OCP, Olefiin Copolymer), styrene butadiene rubber (SBR), LSH polymethacrylate (PMA, LSH Polymethacrylate), and at least one selected from the group consisting of combinations thereof.

The antiwear agent is at least one selected from the group consisting of zinc alkyl dithiophosphate (ZnDTP), amine phosphate, isobutynyl succinic ester, and combinations thereof can include

The transmission oil composition may have a kinetic friction coefficient of 0.079 to 0.081, a kinematic viscosity (40° C.) of 20.6 to 21.2 cSt, and an FZG gear durability of 84 to 108 hours.

The transmission oil composition according to the present invention is formulated with a metallocene-based resin effective for forming an oil film and a friction modifier including a phosphoric acid ester-based compound that has not been used before in a specific mixing ratio, thereby reducing noise generated in the transmission and improving durability of the transmission. can improve

The effects of the present invention are not limited to the effects mentioned above. It should be understood that the effects of the present invention include all effects that can be inferred from the following description.

The above objects, other objects, features and advantages of the present invention will be easily understood through the following preferred embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content will be thorough and complete and the spirit of the present invention will be sufficiently conveyed to those skilled in the art.

In this specification, terms such as "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise specified, all numbers, values and/or expressions expressing quantities of components, reaction conditions, polymer compositions and formulations used herein refer to the number of factors that such numbers arise, among other things, to obtain such values. Since these are approximations that reflect the various uncertainties of the measurement, they should be understood to be qualified by the term "about" in all cases. Also, when numerical ranges are disclosed herein, such ranges are contiguous and include all values from the minimum value of such range to the maximum value inclusive, unless otherwise indicated. Furthermore, where such ranges refer to integers, all integers from the minimum value to the maximum value inclusive are included unless otherwise indicated.

In this specification, where ranges are stated for a variable, it will be understood that the variable includes all values within the stated range inclusive of the stated endpoints of the range. For example, a range of "5 to 10" includes values of 5, 6, 7, 8, 9, and 10, as well as any subrange of 6 to 10, 7 to 10, 6 to 9, 7 to 9, and the like. inclusive, as well as any value between integers that fall within the scope of the stated range, such as 5.5, 6.5, 7.5, 5.5 to 8.5 and 6.5 to 9, and the like. Also, for example, the range of "10% to 30%" includes values such as 10%, 11%, 12%, 13%, etc., and all integers up to and including 30%, as well as values from 10% to 15%, 12% to 12%, etc. It will be understood to include any sub-range, such as 18%, 20% to 30%, and the like, as well as any value between reasonable integers within the scope of the stated range, such as 10.5%, 15.5%, 25.5%, and the like.

The transmission oil composition according to the present invention includes a friction modifier including a base oil, a metallocene-based resin, and a phosphoric acid ester-based compound.

The transmission oil composition according to the present invention may further include a viscosity modifier, an antiwear agent and an additive, preferably 75 to 85% by weight of a base oil, 2 to 6% by weight of a metallocene resin, 0.3 to 0.5% by weight of a friction modifier, viscosity 5 to 15% by weight conditioning agent and 3 to 5% by weight antiwear agent.

It is revealed in advance that the content of each component of the transmission oil composition according to the present invention to be described below is based on 100% by weight of the transmission oil composition. If the criteria are changed, the changed criteria will always be specified, so those with ordinary knowledge will be able to clearly know what composition the content is based on.

A more detailed description of each component constituting the transmission oil composition according to the present invention is as follows.

(1) base oil

Base oil is a basic component of lubricating oil and can be adjusted according to the content ratio of other additives.

The base oil may be included in an amount of 75 to 85% by weight based on the total content of the transmission oil composition. At this time, if the content of the base oil is less than 75% by weight, the viscosity increases as the content of other additives increases, resulting in a decrease in fuel economy. .

The base oil may include at least one selected from mineral oils, synthetic oils, and combinations thereof classified into groups 3 to 5 in the API (American Petroleum Institute) base oil category.

Here, mineral oil is atmospheric resid obtained by atmospheric distillation of crude oil such as paraffinic, intermediate, naphthenic, etc., distilled oil obtained by distilling the atmospheric resid under reduced pressure, and solvent dewaxing, solvent extraction, hydrocracking, and solvent dewaxing. , mineral oil and wax subjected to at least one of refining processes such as catalytic dewaxing and hydrorefining.

Synthetic oils are poly-α-olefins such as polybutene and α-olefin homopolymers or copolymers (for example, α-olefin homopolymers or copolymers having 8 to 14 carbon atoms such as ethylene-α-olefin copolymers). PAO), various esters such as polyol esters, dibasic acid esters, and phosphoric acid esters, various ethers such as polyphenyl ether, polyglycols, alkylbenzenes, alkylnaphthalenes, and waxes (GTL waxes) produced by the Fischer-Tropsch method, etc. may be obtained.

The base oil preferably belongs to Group 3, and typically Yubase 3, Yubase L3, and Ultra S3 products can be used. Here, the base oil of Group 3 has a sulfur content of more than 0 and less than 0.03% by weight, a saturation of 90% by weight or more, a viscosity index of 120 or more, and a kinematic viscosity of 2.8 at 100 ° C. ~ 3.2 cSt. At this time, the base oil of Group 3 has good adaptability to low and high temperatures, has an antioxidant function, and has excellent viscosity retention, so it can be used for a long time without deformation.

(2) Metallocene resin

The metallocene-based resin is a synthetic base oil for reducing fluid frictional resistance by forming an oil film, and may be included in an amount of 2 to 6% by weight based on the total content of the transmission oil composition. At this time, if the content is less than 2% by weight, the durability improvement effect is insignificant, and if it exceeds 6% by weight, fluid friction and viscosity increase, thereby reducing the fuel efficiency improvement effect. Preferably, the metallocene-based resin is included in an amount of 4 to 6% by weight in order to effectively reduce the frictional resistance of the fluid.

The metallocene-based resin may include metallocene polyalpha olefin (mPAO) polymerized with a metallocene catalyst.

The metallocene polyalphaolefin may be a compound represented by Formula 1 below. In the metallocene polyalphaolefin, hydrocarbon molecules, which are functional groups in Chemical Formula 1 below, are adsorbed on the metal surface of the transmission to play a role in smoothing the movement when the fluid flows, thereby reducing fluid resistance.

[Formula 1]

The metallocene polyalpha olefin may have a kinematic viscosity of 150 to 160 cSt at 100 °C and a weight average molecular weight (Mw) of 1000 to 30000 g/mol. If the kinematic viscosity of the metallocene polyalpha olefin is less than 150 cSt, it cannot play a sufficient role in reducing metal friction resistance. Conversely, if it exceeds 160 cSt, the viscosity of the oil becomes excessively high, resulting in deterioration of fuel efficiency. Preferably, the metallocene polyalphaolefin has a kinematic viscosity of 154 to 158 cSt at 100° C. and a weight average molecular weight (Mw) of 15000 to 20000 g/mol.

The metallocene polyalphaolefin may be obtained by copolymerization of a metallocene compound with an alphaolefin by cross-linking.

Here, as the metallocene compound, the metallocene compound is bis (cyclopentadienyl) zirconium dichloride, bis (methylcyclopentadienyl) zirconium dichloride, bis (ethylcyclopentadienyl) zirconium dichloride, bis (iso-propylcyclopentadienyl)zirconium dichloride, bis(n-propylcyclopentadienyl)zirconium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride, bis(t-butylcyclopentadienyl ) Zirconium dichloride, bis (dexylcyclopentadienyl) zirconium dichloride, bis (trimethylsilylcyclopentadienyl) zirconium dichloride, bis (trimethylsilylmethylcyclopentadienyl) zirconium dichloride, bis (cyclopentadienyl) Nyl) may include any one selected from the group consisting of zirconium chlorohydride, bis (cyclopentadienyl) methyl zirconium chloride, and bis (cyclopentadienyl) ethyl zirconium chloride.

The alpha olefin may be a monomer having 6 to 12 carbon atoms. At this time, the alpha olefin has a characteristic of reducing the frictional resistance of the metal surface in the transmission along with the functional group of the friction modifier.

(3) Friction modifier

Friction modifiers have characteristics that can improve NVH (Noise, Vibration, Harshness) performance by reducing the friction coefficient of manual transmission oil.

The friction modifier may be included in an amount of 0.3 to 0.05% by weight based on the total content of the transmission oil composition. At this time, if the content is less than 0.3% by weight, the effect of reducing the friction coefficient is insignificant, and on the contrary, if it exceeds 0.5% by weight, the friction coefficient is excessively lowered, and durability may be deteriorated. Preferably, the friction modifier is preferably included at 0.04% by weight.

In addition, the friction modifier may have a weight ratio of 1:4 to 1:20 with the metallocene-based resin in the total content of the transmission oil composition, and preferably a weight ratio with the metallocene-based resin of 1:10 to 1:15 can

The friction modifier is a compound represented by Formula 2 below, and may preferably be polyphosphoric acid ester.

[Formula 2]

In Formula 2, the ratio of X and Y is 1:3 to 1:4, and the weight average molecular weight (Mw) is 200,000 g/mol to 400,000 g/mol. In this case, n may be a number in an appropriate range according to the molecular weight.

(4) Viscosity modifier

The viscosity modifier helps the clutch to operate smoothly by lowering the viscosity of the composition, which increases when the transmission oil composition is at a low temperature, and prevents friction and wear between metals by increasing the viscosity of the composition, which decreases when the transmission oil composition is at a high temperature. there is.

The viscosity modifier may include 5 to 15% by weight based on the total content of the transmission oil composition. At this time, if the content is less than 5% by weight, the effect of increasing the viscosity is small and durability may be lowered.

The viscosity modifier is Polybutadiene hydrogen phosphate Comb Polymethacrylate (PHP Comb PMA), Comb Polymethacrylate (Comb PMA), esteric, olefin copolymer (OCP, Olefiin Copolymer), styrene butadiene rubber (SBR), LSH polymethacrylate (PMA, LSH Polymethacrylate), and at least one selected from the group consisting of combinations thereof. Preferably, polybutadiene hydrogen phosphate comb polymethacrylate having excellent high-temperature expandability and low-temperature shrinkage may be used.

Here, the polybutadiene hydrogen phosphate comb polymethacrylate may have a structural formula shown in Chemical Formula 3 below.

[Formula 3]

Here, the ratio of X and Y is 1:2 to 1:3, the weight average molecular weight (Mw) may be 150,000 g / mol to 300,000 g / mol, and R1 is hydrogen phosphate (Hydrogen phosphate ) may include a hydrophilic monomer as a monomer having a structure, and R2 may include polybutadiene having a weight average molecular weight (Mw) of 1,500 to 2,500 and carbon atoms of 1 to 20. In this case, n may be a number in an appropriate range according to the molecular weight.

[Formula 4]

That is, by introducing a side chain into which a hydrophilic monomer is introduced into the main chain of comb polymethacrylate (Comb PMA) and introducing polybutadiene into a carboxylate group bonded to the main chain, low-temperature shrinkage and By maximizing high-temperature expandability, low-temperature viscosity of transmission oil can be lowered to improve fuel efficiency, and high-temperature viscosity can be increased to improve durability.

(5) Anti-wear agent

The antiwear agent serves to prevent abrasion by forming a protective film on the surface of a friction metal such as a friction material or a metal plate, and is preferably used in an amount of 3 to 5% by weight based on the total weight of transmission oil. When the content of c is less than 3% by weight, wear resistance deteriorates and there is a limit to maintaining durability, and when the content exceeds 15% by weight, durability may deteriorate due to a decrease in friction coefficient due to excessive additives, so within the above range good to use

Antiwear agents include zinc alkyl dithiophosphate (ZnDTP), amine phosphate, isobutynyl succinic ester, molybdenum dithiocarbamate (MoDTC), dibutyl hydroxy It may include at least one selected from the group consisting of rosen phosphite and combinations thereof.

(6) Additives

In the present invention, a cleaning dispersing agent, an antioxidant, and an antifoaming agent may be further included as conventional additives.

The cleaning dispersant can keep the clutch clean by dispersing and floating deposits such as oxides or some sludge generated by oxidation of the automatic transmission oil composition in the engine and transmission in the form of fine particles, and calcium salicylate ), calcium sulfonate, or a mixture thereof,

Antioxidants are used for the purpose of preventing oxidation of engine oil, and amine-based antioxidants such as 3-hydroxydiphenylamine and phenyl-alpha-naphthylamine may be used.

The antifoaming agent may include at least one selected from the group consisting of silicone and polymethacrylate.

As described above, the transmission oil composition according to the present invention may have a kinetic friction coefficient of 0.079 to 0.081, a kinematic viscosity (40° C.) of 20.6 to 21.2 cSt, and an FZG gear durability of 84 to 108 hours. When all of these conditions are satisfied, noise reduction and durability improvement of the transmission can be maximized.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are merely examples to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Examples and Comparative Examples

Transmission oil compositions were prepared by a conventional method with the ingredients and contents shown in Tables 1 and 2 below.

Classification (% by weight) Example One 2 3 4 5 6 7 base oil Group 3 76.6 75.6 74.6 73.6 72.6 74.7 74.5 metallocene resin mPAO 2 3 4 5 6 4 4 main additive calcium sulfonate 8 8 8 8 8 8 8 friction modifier Polyphosphoric acid ester 0.4 0.4 0.4 0.4 0.4 0.3 0.5 viscosity modifier Polybutadienehydrogen phospate
Comb PMA 10 10 10 10 10 10 10 antiwear agent Zinc Alkyl Dithiophosphate 3 3 3 3 3 3 3

Classification (% by weight) comparative example One
(current specification) 2 3 4 5 6 7 base oil Group 3 79 77.6 71.6 75 74.75 74.45 78.6 metallocene resin mPAO - One 7 4 4 4 - main additive calcium sulfonate 8 8 8 8 8 8 8 friction modifier Polyphosphoric acid ester - 0.4 0.4 - 0.25 0.55 0.4 viscosity modifier Polybutadiene
hydrogen phospate
Comb PMA 10 10 10 10 10 10 10 antiwear agent Zinc Alkyl Dithiophosphate 3 3 3 3 3 3 3

[Each component constituting the transmission oil composition]

(1) Base oil: Group 3, Yubase3

(2) Metallocene resin: mPAO (metallocnene polyalpha olefin), product of Exxon Mobil

(3) Friction modifier: Polyphosphoric acid ester having a weight average molecular weight (Mw) of 200,000 to 400,000 g/mol

(4) Viscosity modifier: Polybutadiene hydrogen phosphate Comb Polymethacrylate containing hydrogen phosphate and polybutadiene and having a weight average molecular weight (Mw) of 150,000 to 300,000 g/mol

(5) Antiwear agent: zinc alkyldithiophosphate, product of Lubrizol

(6) Main additive: calcium sulfonate

Experimental example

The transmission oil compositions prepared in Examples 1 to 7 and Comparative Examples 1 to 7 were evaluated by the following method, and the results are shown in Tables 3 and 4 below.

[Assessment Methods]

(1) Synchro dynamic friction coefficient (self-test): Measure the dynamic friction between the friction material and the steel plate under the condition of 1200 rpm x 41 kgf x 80 ℃

(2) Kinematic viscosity at 40℃ (ASTM D445): Suck up the sample with a glass tube in a bath maintained at 40℃ and measure the dripping time to convert to kinematic viscosity

(3) Noise evaluation (self-test): Measure the noise after driving at a vehicle speed of 15 to 20 kph or more after full turn (the evaluation result is expressed as 6-, 6, 6+, 7-, 7, 7+, the higher the number indicates less noise)

(4) FZG gear endurance time (FVA No.2/Ⅳ): Measure the time for pitting after test evaluation at 1450rpm x 90℃ x 9 load stage

evaluation item Example One 2 3 4 5 6 7 synchro
Dynamic friction coefficient 0.081 0.081 0.080 0.080 0.080 0.081 0.079 Kinematic viscosity at 40°C (cSt) 20.6 20.8 21 21.2 21.2 20.9 21.1 noise evaluation 7- 7- 7 7 7 7- 7- FZG gear endurance time (h) 84 102 108 102 102 90 96

evaluation item comparative example
One
(current specification) 2 3 4 5 6 7 synchro
Dynamic friction coefficient 0.087 0.083 0.083 0.087 0.086 0.078 0.084 40℃
Kinematic Viscosity (cSt) 20.2 20.3 21 20.5 20.3 21.2 20.3 noise evaluation 6+ 6+ 6+ 6 6+ 6+ 6+ FZG gear endurance time (h) 72 72 78 72 72 66 72

According to the results of Tables 3 and 4, the weight ratio of mPAO and polyphosphoric acid ester in the transmission oil composition is 4: 1 to 20: 1, and the content of mPAO is 2 to 6% (Examples 1 to 5), Polyphosphoric acid When the ester content is added in the range of 0.3 to 0.5% (Examples 3, 6, and 7), the noise reduction improvement effect (-7 points, 7 points) is excellent, and the FZG endurance time is 84 to 108 hours. Compared to Comparative Examples 1 to 7, it was confirmed that the noise was reduced and the durability was improved at the same time.

In particular, when the contents of mPAO and polyphosphoric acid ester were added in a ratio of 10: 1 to 15: 1 in the transmission oil composition (Examples 3, 4, and 5), the effect of improving noise reduction (7 points) and the durability of FZG were 102 At ~ 108 hours, noise reduction and durability were significantly improved compared to Comparative Example 1, which is the current specification. Among them, it was confirmed that Example 3 has the most appropriate coefficient of friction, so the noise reduction improvement effect (7 points) is large, and the FZG durability time is 108 hours, which is improved by more than 50% compared to Comparative Example 1, which is the current specification. did

This is because the functional groups of the two materials, mPAO and polyphosphoric acid ester, are adsorbed on the stainless steel material inside the transmission differential to reduce the resistance between metals, thereby reducing the noise caused by local extreme pressure friction and also protecting the gear material, thereby increasing the durability of the transmission as well. it is improved

On the other hand, in the case of Comparative Example 2 containing a small amount of mPAO, the effect of improving durability was not good because the increase in viscosity was low and the effect of increasing the oil film was poor. Conversely, in the case of Comparative Example 3 containing too much mPAO content, it was confirmed that the viscosity was high, but the reduction in friction coefficient was low, and the noise improvement effect was low.

In addition, in the case of Comparative Example 5 containing a very small amount of polyphosphoric acid ester, the friction reduction effect was low and the noise improvement was insufficient, and as a result, the fuel efficiency and wear resistance were poor. On the contrary, in the case of Comparative Example 6 containing a large amount of polyphosphoric acid ester, it was confirmed that the friction coefficient was too low, causing slippage between gears, resulting in deterioration in durability.

In addition, when mPAO was not used at all (Comparative Example 7) or when Polyphosphoric acid ester was not used at all (Comparative Example 4), the effect of reducing the friction coefficient and improving durability was insufficient.

Therefore, the transmission oil composition according to the present invention is formulated with a metallocene-based resin effective for forming an oil film and a friction modifier including a phosphoric acid ester-based compound that has not been used before in a specific mixing ratio, thereby reducing noise generated in the transmission and improving transmission performance. durability can be improved.

Although the embodiments of the present invention have been described above, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing its technical spirit or essential features. . Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (10)

base oil;
metallocene-based resins; and
A transmission oil composition comprising a friction modifier comprising a phosphoric acid ester compound. According to claim 1,
viscosity modifier; and
A transmission oil composition further comprising; an antiwear agent. According to claim 2,
75 to 85% by weight of the base oil;
2 to 6% by weight of the metallocene resin;
0.3 to 0.5% by weight of the friction modifier;
5 to 15% by weight of the viscosity modifier; and
A transmission oil composition comprising 3 to 5% by weight of the antiwear agent. According to claim 1,
The base oil is a transmission oil composition comprising at least one selected from mineral oil, synthetic oil, and combinations thereof classified into groups 3 to 5 in the API (American Petroleum Institute) base oil category. According to claim 1,
The metallocene-based resin is a transmission oil composition comprising a poly alpha olefin (mPAO) polymerized with a metallocene catalyst. According to claim 1,
A transmission oil composition wherein the weight ratio of the metallocene-based resin and the friction modifier is 4:1 to 20:1. According to claim 1,
The transmission oil composition wherein the friction modifier is a compound represented by Formula 1 below.
[Formula 1]

(In Formula 1, the ratio of X and Y is 1:3 to 1:4, and the weight average molecular weight (Mw) is 200,000 g/mol to 400,000 g/mol.) According to claim 2,
The viscosity modifier,
Polybutadiene hydrogen phosphate Comb Polymethacrylate (PHP Comb PMA), Comb Polymethacrylate (Comb PMA), Asteric, Olefiin Copolymer (OCP) A transmission oil composition comprising at least one selected from the group consisting of , Styrene Butadiene Rubber (SBR), LSH Polymethacrylate (PMA), and combinations thereof. According to claim 2,
The antiwear agent,
Transmission oil containing at least one selected from the group consisting of zinc alkyl dithiophosphate (ZnDTP), amine phosphate, isobutynyl succinic ester, and combinations thereof composition. According to claim 1,
A transmission oil composition having a kinetic coefficient of friction of 0.079 to 0.081, a kinematic viscosity (40° C.) of 20.6 to 21.2 cSt, and a FZG gear durability of 84 to 108 hours.