Lubricant compositions having two base oil stocks

Abstract

Lubricant compositions and methods of use thereof. Lubricant compositions may comprise: about 70 wt % to about 99.99 wt % of a first oil base stock, wherein the first oil base stock comprises an API Group II extra heavy oil base stock, the API Group II extra heavy oil base stock having: a kinematic viscosity (ASTM D445, 40° C.) of about 320 cSt to about 520 cSt, a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 36 cSt, a viscosity index (ASTM D2270) of about 80 to about 119, a pour point (ASTM D97) of about −6° C. or less, and a saturate content (ASTM D7419) of about 90 wt % or greater; and about 0 wt % to about 30 wt % of a second oil base stock, wherein the second oil base stock comprises an API Group I oil base stock, the API Group I oil base stock having: a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 15 cSt.

Description

FIELD OF INVENTION

[0001] This application relates to lubricant compositions and methods related thereto.BACKGROUND

[0002] Lubricant compositions (e.g., lubricants, oils, and the like) are used in a variety of mechanical applications for smoothing the operation thereof. Example applications may include internal combustion engines, industrial machinery, gear systems, and the like. Furthermore, lubricant compositions may serve additional roles within desired applications including, but not limited to, cooling machinery, cleansing components, as well as preventing rust and / or corrosion. Lubricant compositions may be subject to various wear and degradation, including oxidation of the lubricant oil itself, leading to reduced lubrication performance.

[0003] A variety of base stocks may be available for formulation of lubricant compositions, including base stocks in American Petroleum Institute (API) groups I through V. The API defines Group I oil base stocks as solvent-refined mineral oils; Group I oil base stocks contain the least saturates and highest amount of sulfur and generally have the lowest viscosity indices. Group I generally defines the bottom tier of lubricant performance. Group II and Group III oil base stocks are high viscosity index and very high viscosity index base stocks, respectively. The Group III oil base stocks generally contain fewer unsaturates and sulfur than the Group II oils. Group IV oil base stocks consist of polyalphaolefins, which are produced via the catalytic oligomerization of linear alphaolefins (LAOs). Group V includes all the other oil base stocks not included in Groups I through IV; Group V base stocks include lubricants based on or derived from esters.SUMMARY OF INVENTION

[0004] According to an embodiment consistent with the present disclosure, lubricant compositions comprise: about 70 wt % to about 99.99 wt % of a first oil base stock, wherein the first oil base stock comprises an API Group II extra heavy oil base stock, the API Group II extra heavy oil base stock having: a kinematic viscosity (ASTM D445, 40° C.) of about 320 cSt to about 520 cSt, a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 36 cSt, a viscosity index (ASTM D2270) of about 80 to about 119, a pour point (ASTM D97) of about −6° C. or less, and a saturate content (ASTM D7419) of about 90 wt % or greater; about 0 wt % to about 30 wt % of a second oil base stock, wherein the second oil base stock comprises an API Group I oil base stock, the API Group I oil base stock having: a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 15 cSt.

[0005] According to another embodiment consistent with the present disclosure, methods for producing a circulating oil composition comprise: optionally, preparing a base oil for a circulating oil composition by blending a first oil base stock for the base oil and a second oil base stock for the base oil, thereby forming the base oil, the base oil comprising: about 70 wt % to about 99.99 wt % of a first oil base stock, wherein the first oil base stock comprises an API Group II extra heavy oil base stock, the API Group II extra heavy oil base stock having: a kinematic viscosity (ASTM D445, 40° C.) of about 320 cSt to about 520 cSt, a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 36 cSt, a viscosity index (ASTM D2270) of about 80 to about 119, a pour point (ASTM D97) of about −6° C. or less, and a saturate content (ASTM D7419) of about 90 wt % or greater; and about 0 wt % to about 30 wt % of a second oil base stock, wherein the second oil base stock comprises an API Group I oil base stock, the API Group I oil base stock having: a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 15 cSt; providing the base oil; optionally, providing an R&O additive package, a pour point depressant, and / or an anti-foam additive; and optionally, blending the base oil with the R&O additive package, the pour point depressant, and / or the anti-foam additive.

[0006] These and other features and attributes of the disclosed compositions and methods of the present disclosure and their advantageous applications and / or uses will be apparent from the detailed description which follows.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawings. The following figures are included to illustrate certain aspects of the disclosure and should not be viewed as exclusive configurations. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure.

[0008] FIG. 1 is a graph of total acid number (TAN) change for example compositions according to the present disclosure.

[0009] FIG. 2 is a graph of viscosity increase for example compositions according to the present disclosure.

[0010] FIG. 3 is a graph of failure time for example compositions according to the present disclosure.DETAILED DESCRIPTION

[0011] This application relates to lubricant compositions and methods related thereto and, particularly, to circulating oil compositions and methods related thereto.

[0012] The term “mass %” as used herein indicates percentage by mass such as percentage by weight (e.g., wt %), “vol %” as used herein indicates percentage by volume, “mol %” as used herein indicates percentage by mole, “ppm” as used herein indicates parts per million, and “ppm wt” and “wppm” are used interchangeably and mean parts per million on a weight basis. All concentrations herein, unless otherwise stated, are expressed on the basis of the total amount of the composition in question.

[0013] The term “polymer” as used herein refers to any two or more of the same or different repeating units / mer unit or units. The term “homopolymer” as used herein refers to a polymer having units that are the same. The term “copolymer” as used herein refers to a polymer having two or more units that are different from each other and includes terpolymers and the like. The term “terpolymer” as used herein refers to a polymer having three units that are different from each other. The term “different” as used herein as it refers to units indicates that the units differ from each other by at least one atom or are different isomerically. Likewise, the definition of polymer, as used herein, includes homopolymers, copolymers, and the like.

[0014] The term “alphaolefin” refers to any linear or branched compound of carbon and hydrogen having at least one double bond between the a and R carbon atoms. For purposes of this specification and the claims appended thereto, when a polymer or copolymer is referred to as including an alpha-olefin (e.g., a polyalphaolefin) the alpha-olefin present in such polymer or copolymer is the polymerized form of the alpha-olefin.

[0015] The term “oil base stock” as used herein refers to any base fluid that could be used in a lubricant including, but not limited to, a terpene, a mineral oil, a synthetic hydrocarbon, an ester, the like, or any combination thereof. An oil base stock as used herein may include Group I, II, III, IV, and V (as defined by American Petroleum Institute [API]) base oils, including any combination thereof. The terms “base oil”, “oil base stock”, “oil basestock,”“basestock oil,”“base stock oil,” simply “base stock,” or any grammatical variations thereof are used interchangeably herein.

[0016] According to the American Petroleum Institute (API) classifications, base stocks are categorized in five groups based on their saturated hydrocarbon content (saturates) (quoted as a weight percent (wt %)), sulfur level (wt %), and viscosity index (see Table 1 below). Lubricant base stocks are typically produced in large scale from petroleum sources. Group I, II, and III base stocks are derived from crude oil via processing, such as solvent extraction, hydroprocessing, solvent or catalytic dewaxing, and hydroisomerization. Group III base stocks also can be produced from synthetic hydrocarbon liquids obtained from natural gas, coal or other fossil resources; Group IV base stocks, the polyalphaolefins (PAO), are produced by oligomerization of alpha olefins, such as 1-decene; Group V base stocks include everything that does not belong to Groups I-IV, such as naphthenics, polyalkylene glycols (PAG), and esters.TABLE 1API Basestock Group Classifications.APIViscosityClassificationwt % Saturateswt % SulfurIndex (VI)Group I<90 and / or>0.03 and≥80 and <120Group II≥90 and≤0.03 and≥80 and <120Group III≥90 and≤0.03 and≥120Group IVPolyalphaolefins (PAO)Group VAll others not in Groups I, II, III, or IV

[0017] Lubricating base oils the present disclosure may be derived from any suitable source. Base stock oils useful in the present disclosure may include natural oils, synthetic oils, and / or unconventional oils (or mixtures thereof). Base stock oils suitable for the present disclosure may be used unrefined, refined, or rerefined (the latter is also known as reclaimed or reprocessed oil). Unrefined oils are those obtained directly from a natural or synthetic source and used without added purification and may include shale oil obtained directly from retorting operations, petroleum oil obtained directly from primary distillation, and ester oil obtained directly from an esterification process. Refined oils are similar to the oils discussed for unrefined oils except refined oils are subjected to one or more purification steps to improve at least one lubricating oil property. One skilled in the art will be familiar with many purification processes. Such purification processes may include solvent extraction, secondary distillation, acid extraction, base extraction, filtration, percolation, and the like. Rerefined oils may be obtained by processes analogous to refined oils but using an oil that has been previously used as a feed stock. Other processes may be used for production of oils of the present disclosure.

[0018] Lubricant compositions of the present disclosure may be suitable lubricants for a variety of applications including, but not limited to, industrial lubricants, automotive lubricants, the like, or any combination thereof. Lubricant composition of the present disclosure may provide increased oxidation resistance, allowing for increased usable lifespan of the lubricant composition and reducing wear and tear on mechanical components surrounding the lubricant compositions.

[0019] Lubricant compositions of the present disclosure may comprise one or more base stocks in combination, including two or more base stocks, such as a first oil base stock and, optionally, a second oil base stock.

[0020] Lubricant compositions of the present disclosure may include the first oil base stock at a concentration of about 60 wt % to about 99.99 wt %, or about 70 wt % to about 99.99 wt %, or about 75 wt % to about 99 wt %, or about 70 wt % to about 80 wt %, or about 98 wt % to about 99.99 wt %, or about 99 wt % to about 99.99 wt %, or about 99.0 wt % to about 99.1 wt %.

[0021] Suitable first oil base stocks may include suitable API Group II base stocks such as group II extra heavy oil base stocks. Group II extra heavy oil base stocks of interest in the present disclosure, may have a kinematic viscosity (ASTM D445, 40° C.) of about 300 centistokes (cSt) to about 600 cSt (or about 320 cSt to about 520 cSt, or about 380 cSt to about 520 cSt, or about 450 cSt to about 520 cSt) and a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 40 cSt (or about 22 cSt to about 36 cSt, or about 27 cSt to about 36 cSt, or about 32 cSt to about 36 cSt). Suitable Group II extra heavy oil base stocks may have a viscosity index (ASTM D2270) of about 80 to about 119 (or about 95 to about 115). Suitable Group II extra heavy oil base stocks may have a pour point (IP 15 or ASTM D97) of about −35° C. to about −6° C. (or about −35° C. to about −15° C., or about −6° C. or less, or about −15° C. or less). Suitable Group II extra heavy oil base stocks may have a saturate content (ASTM D7419) of about 90 wt % or greater (or about 90 wt % to about 99.99 wt %, or about 95 wt % to about 99.99 wt %, or about 98 wt % to about 99.99 wt %, or about 90 wt % to about 99 wt %, or about 95 wt % to about 99 wt %, or about 98 wt % to about 99 wt %, or about 95 wt % or greater, or about 98 wt % or greater, or about 99 wt % or greater). Other characteristics of suitable Group II extra heavy oil base stocks may include, but are not limited to: base stock color (ASTM D6045) of L1.5 to L0.5 (or L1.5 to L1.0, or L1.0 to L0.5); carbon residue (ASTM D4530) of about 0.0001 mass % to about 0.1 mass %, or about 0.001 mass % to about 0.01 mass %, or about 0 mass % to about 0.1 mass %, or about 0 mass % to about 0.01 mass %, or about 0.1 mass % or less, or about 0.01 mass % or less; cloud point (ASTM D2500) of about −60° C. to about −2° C., or about −60° C. to about −30° C., or about −30° C. to about −2° C., or about −2° C. or less, or about −30° C. or less, or about −60° C. or less; flashpoint (ASTM D92) of about 250° C. to about 300° C., or about 250° C. to about 275° C., or about 275° C. to about 300° C., or about 250° C. or greater. Suitable Group II extra heavy oil base stocks for use as a first oil base stock may include those commercially available under the tradenames EHC™ (including, but not limited to, EHC 340 MAX™) (Exxon Mobil Corporation).

[0022] The first oil base stocks may further comprise API Group I bright stocks. The first oil base stocks may include about 1 wt. % to about 20 wt. % of API Group I bright stocks. “Bright stock,” and grammatical variations thereof, as used herein refers to high viscosity API Group I base oils. API Group I bright stocks are more than standard API Group I base oils. API Group I bright stocks may be refined by running feedstock through a vacuum distillation process, followed by solvent extraction, solvent dewaxing, and hydrofinishing processes. Alternatively, API Group I bright stocks may be refined by hydrotreating and catalytic dewaxing of napthenic crude oil. API Suitable API Group I bright stocks may have a kinematic viscosity (ASTM D445, 100° C.) of greater than about 20 cSt to about 40 cSt, or about 25 cSt to about 38 cSt, or about 30 cSt to about 36 cSt. Suitable API Group I bright stocks for use as a first oil base stock may include those commercially available under the tradenames Americas Core 2500 (Exxon Mobil Corporation). The first oil base stocks may include substantially no API Group I bright stocks, including substantially no API Group I bright stocks. “Substantially no,” and grammatical variations thereof, as used herein, refers to a composition including an amount of a compound such that the composition has no discernable properties indicating the presence of the compound, including, but not limited to, for example, less than about 1 wt %, or less than about 0.1 wt %, or less than about 0.01 wt %, or less than about 0.001 wt % of a compound. Lubricant compositions of the present disclosure may use the Group II extra heavy oil base stocks to replace API Group I bright stocks present in corresponding lubricant compositions (e.g., commercially available lubricant oil formulations).

[0023] Lubricant compositions of the present disclosure may optionally include a second oil base stock. Lubricant compositions of the present disclosure may include a second oil base stock at a concentration of about 0 wt % to about 30 wt %, or about 0 wt % to about 1 wt %, or less than about 0.1 wt %, or about 20 wt % to about 25 wt %, or about 20 wt % to about 30 wt %. Suitable second oil base stocks may include API Group I oil base stocks. API Group I oil base stocks may have a kinematic viscosity (ASTM D445, 100° C.) of about 20 cSt or less (e.g., API Group I oil base stocks may exclude API Group I bright stocks). Second oil base stocks may have a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 20, or cSt 2 cSt to about 15 cSt, or about 3 cSt to about 5 cSt, or about 4 cSt to about 6 cSt, or about 10 cSt to about 15 cSt. Suitable second oil base stocks may include, but are not limited to, for example, Americas CORE™ 600 and AP / E CORE™ 600 (Exxon Mobil Corporation).Additives

[0024] Lubricant compositions may include one or more various additive(s) for increasing lubricant performance. Additive(s) included in lubricant compositions of the present disclosure may include, rust and oxidation (R&O) additives, pour point depressants, anti-foam additives, or any combination thereof. R&O additives may include rust inhibitors, oxidation inhibitors, and corrosion inhibitors. R&O additives may be included in lubricant compositions of the present disclosure at concentrations of about 0.1 wt % to about 1.5 wt %, or about 0.1 wt % to about 1.0 wt %, or about 0.5 wt % to about 1.0 wt %. Pour point depressants may be included in lubricant compositions of the present disclosure at concentrations of about 0.01 wt % to about 0.5 wt %, or about 0.05 wt % to about 0.5 wt %, or about 0.05 wt % to about 0.2 wt %. Anti-foam additives may be included in lubricant compositions of the present disclosure at concentrations of about 0.001 wt % to about 0.01 wt %, or about 0.003 wt % to about 0.007 wt %.

[0025] Lubricant additives may include, but are not limited to, for example, dispersants, detergents, antiwear additives, viscosity modifiers, corrosion inhibitors, rust inhibitors, metal deactivators, extreme pressure additives, anti-seizure agents, wax modifiers, fluid-loss additives, seal compatibility agents, friction modifiers, lubricity agents, anti-staining agents, chromophoric agents, defoamants, demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants, and others, including combinations thereof. These additive(s) may be delivered with varying amounts of diluent oil. When lubricant compositions include one or more of the foregoing additive(s), the additive(s) may be blended into the compositions in an amount sufficient to perform an intended function. For example, foregoing additive(s) may each be present in lubricant compositions at concentrations of about 0.001 wt % to about 40 wt %, or about 0.001 wt % to about 10 wt %, or about 0.001 wt % to about 5 wt %.Properties

[0026] Lubricant compositions of the present disclosure may have various properties that may allow for equivalent or increased performance, as compared to corresponding lubricant compositions in the absence of Group II extra heavy oil base stocks. For example, lubricant compositions of the present disclosure may achieve equivalent or increased performance in various properties by using the Group II extra heavy oil base stocks to replace API Group I bright stocks present in corresponding lubricant compositions (e.g., commercially available lubricant formulations).

[0027] Properties of lubricant compositions of the present disclosure may include a viscosity (ASTM D445, 40° C.) from about 400 cSt to about 600 cSt, or about 400 cSt to about 550 cSt, or about 400 cSt to about 525 cSt, or about 400 cSt to about 450 cSt, or about 450 cSt to about 500 cSt. Lubricant compositions of the present disclosure may be of ISO Viscosity Grade (VG) 460.

[0028] Properties of lubricant compositions of the present disclosure may include a Total Acid Number (TAN) change of less than about 0.4, or less than about 0.3, or less than about 0.2, or less than about 0.1, or about 0 to about 0.4, or about 0 to about 0.3, or about 0 to about 0.2, or about 0 to about 0.1, or about 0.01 to about 0.4, or about 0.01 to about 0.3, or about 0.01 to about 0.2, or about 0.01 to about 0.1, during 1500 hours of testing according to an ExxonMobil Circulating Oil Oxidation Test, performed using an FZG gear test rig. The ExxonMobil Circulating Oil Oxidation Test is run for 1500 hours at 100° C. with copper and steel catalysts added to the reservoir to make the test more severe. The FZG gears are set to load stage 8 to make the test more severe than a typical circulating oil oxidation test. Lubricant compositions of the present disclosure may have a TAN change during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test which is about 0.1 lower to about 0.5 lower, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock.

[0029] Properties of lubricant compositions of the present disclosure may include a viscosity increase of less than about 9%, or less than about 8%, or less than about 5%, or less than about 4%, or less than about 3%, or about 0% to about 9%, or about 0% to about 6%, or about 0% to about 4%, or about 0.1% to about 9%, or about 0.1% to about 6%, or about 0.1% to about 4%, or about 1% to about 5%, or about 2% to about 4%, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test using the FZG gear test rig, as described above.

[0030] Lubricant compositions of the present disclosure may have a % viscosity increase during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 2% lower to about a 7% lower, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by one or more API Group I bright stocks.

[0031] Properties of lubricant compositions of the present disclosure may include an oxidation time to failure (ASTM D2272 RPVOT) of greater than 325 minutes, or greater than 350 minutes, or greater than 400 minutes, or greater than 450 minutes, or 325 minutes to 500 minutes, or 325 minutes to 475 minutes, or 325 minutes to 450 minutes, or 400 minutes to 800 minutes, or 400 minutes to 700 minutes, or 400 minutes to 600 minutes, or 400 minutes to 500 minutes, or 450 minutes to 475 minutes. Lubricant compositions of the present disclosure may have an oxidation time to failure (ASTM D2272 RPVOT) which is about 90 minutes or greater to about 160 minutes or greater, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock.

[0032] Furthermore, lubricant compositions of the present disclosure may have a reduced sulfur content (ASTM D6443), as compared to corresponding lubricant compositions in the absence of (e.g., where bright stocks take the place of) the Group II extra heavy oil base stock, without a corresponding decrease in oxidation performance.ADDITIONAL EMBODIMENTS

[0033] Embodiment 1. A lubricant composition comprising: about 70 wt % to about 99.99 wt % of a first oil base stock, wherein the first oil base stock comprises an API Group II extra heavy oil base stock, the API Group II extra heavy oil base stock having: a kinematic viscosity (ASTM D445, 40° C.) of about 320 cSt to about 520 cSt, a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 36 cSt, a viscosity index (ASTM D2270) of about 80 to about 119, a pour point (ASTM D97) of about −6° C. or less, and a saturate content (ASTM D7419) of about 90 wt % or greater; about 0 wt % to about 30 wt % of a second oil base stock, wherein the second oil base stock comprises an API Group I oil base stock, the API Group I oil base stock having: a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 15 cSt.

[0034] Embodiment 2. The lubricant composition of Embodiment 1, wherein the lubricant composition comprises about 0 wt % of the second oil base stock.

[0035] Embodiment 3. The lubricant composition of Embodiment 1, wherein the lubricant composition comprises about 20 wt % to about 30 wt % of the second oil base stock.

[0036] Embodiment 4. The lubricant composition of any one of Embodiments 1-3, wherein the first oil base stock comprises less than about 1 weight percent (wt. %) of an API Group I bright stock.

[0037] Embodiment 5. The lubricant composition of any one of Embodiments 1-4, further comprising: about 0.1 wt % to about 1.5 wt % of a R&O additive package, the R&O additive package comprising a rust inhibitor, an oxidation inhibitor, and a corrosion inhibitor; about 0.05 wt % to about 0.5 wt % of a pour point depressant; and / or about 0.001 wt % to about 0.01 wt % of an anti-foam additive.

[0038] Embodiment 6. The lubricant composition of any one of Embodiments 1-5, wherein the lubricant composition has a TAN change of less than about 0.2 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

[0039] Embodiment 7. The lubricant composition of any one of Embodiments 1-6, wherein the lubricant composition has a % viscosity increase of less than about 5 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

[0040] Embodiment 8. The lubricant composition of any one of Embodiment 1-7, wherein the lubricant composition has an oxidation time to failure (ASTM D2272 RPVOT) of about 400 minutes to about 800 minutes.

[0041] Embodiment 9. The lubricant composition of any one of Embodiments 1-8, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock: a TAN change, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 0.1 lower to about 0.5 lower; and / or a % viscosity increase, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 2% lower to about a 7% lower.

[0042] Embodiment 10. The lubricant composition of any one of Embodiments 1-9, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock: an oxidation time to failure (ASTM D2272 RPVOT) which is about 90 minutes greater to about 160 minutes greater.

[0043] Embodiment 11. A method for producing a circulating oil composition, the method comprising: optionally, preparing a base oil for a circulating oil composition by blending a first oil base stock for the base oil and a second oil base stock for the base oil, thereby forming the base oil, the base oil comprising: about 70 wt % to about 99.99 wt % of a first oil base stock, wherein the first oil base stock comprises an API Group II extra heavy oil base stock, the API Group II extra heavy oil base stock having: a kinematic viscosity (ASTM D445, 40° C.) of about 320 cSt to about 520 cSt, a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 36 cSt, a viscosity index (ASTM D2270) of about 80 to about 119, a pour point (ASTM D97) of about −6° C. or less, and a saturate content (ASTM D7419) of about 90 wt % or greater; and about 0 wt % to about 30 wt % of a second oil base stock, wherein the second oil base stock comprises an API Group I oil base stock, the API Group I oil base stock having: a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 15 cSt; providing the base oil; optionally, providing an R&O additive package, a pour point depressant, and / or an anti-foam additive; and optionally, blending the base oil with the R&O additive package, the pour point depressant, and / or the anti-foam additive.

[0044] Embodiment 12. The method of Embodiment 11, wherein the lubricant composition comprises about 0 wt % of the second oil base stock.

[0045] Embodiment 13. The method of Embodiment 11, wherein the lubricant composition comprises about 20 wt % to about 30 wt % of the second oil base stock.

[0046] Embodiment 14. The method of any one of Embodiments 11-13, wherein the first oil base stock replaces comprises less than about 1 weight percent (wt. %) of an API Group I bright stock.

[0047] Embodiment 15. The method of any one of Embodiments 11-14, further comprising: about 0.1 wt % to about 1.5 wt % of a R&O additive package, the R&O additive package comprising a rust inhibitor, an oxidation inhibitor, and a corrosion inhibitor; about 0.05 wt % to about 0.5 wt % of a pour point depressant; and / or about 0.001 wt % to about 0.01 wt % of an anti-foam additive

[0048] Embodiment 16. The method of any one of Embodiments 11-15, wherein the lubricant composition has a TAN change of less than 0.2 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

[0049] Embodiment 17. The method of any one of Embodiments 11-16, wherein the lubricant composition has a % viscosity increase of less than 5 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

[0050] Embodiment 18. The method of any one of Embodiments 11-17, wherein the lubricant composition has an oxidation time to failure (ASTM D2272 RPVOT) of 400 minutes to 800 minutes.

[0051] Embodiment 19. The method of any one of Embodiments 11-18, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock: a TAN change, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 0.1 lower to about 0.5 lower; and / or a % viscosity increase, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 2% lower to about a 7% lower.

[0052] Embodiment 20. The method of any one of Embodiments 11-19, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock: an oxidation time to failure (ASTM D2272 RPVOT) which is about 90 minutes greater to about 160 minutes greater.

[0053] To facilitate a better understanding of the embodiments of the present invention, the following examples of preferred or representative embodiments are given. In no way should the following examples be read to limit, or to define, the scope of the invention.EXAMPLES

[0054] Circulating oils are a specific class of lubricating oils. Circulating oils are lubricating oils for the centralized continuous and reusable lubrication of various systems, to protect critical components such as bearings, blowers, gearboxes, or the like, for a wide range of purposes (e.g., heat exchange, friction reduction, and prevention of wear, corrosion, and rust). Circulating oils operate under conditions of high temperature, exposure to filtration operations, long oil drain intervals, and contact with moisture and other contaminants. Further, circulating oils require exceptional oil life, often tens of thousands of hours. Due to the millions of gallons of these oils used annually, circulating oils must have excellent thermal stability, oxidative stability, filterability, foaming resistance, compatibility with multiple materials, low traction coefficient, low temperature fluidity, and high film thickness at high temperatures. Improved oxidation stability, for example, can lead to longer oil life in severe oil service.Experiment 1: Formulations

[0055] Example lubricant compositions were formed in two areas, A and B. Example compositions in area A included an API Group II extra heavy oil base stock oil comprising EHC 340 MAX™ (available from Exxon Mobil Corporation) as a first oil base stock. Furthermore, example compositions in area B included an API Group I oil base stock comprising Americas CORE™ 600 (available from Exxon Mobil Corporation) as a second oil base stock in addition to the API Group II extra heavy oil base stock oil comprising EHC 340 MAX™ (available from Exxon Mobil Corporation) as the first oil base stock. Comparative Example compositions in area A included an API Group I bright stock as a comparative example first oil base stock, specifically comprising AP / E CORE™ 2500 (available from Exxon Mobil Corporation) for area A and Americas CORE™ 2500 (available from Exxon Mobil Corporation) for area B. Additionally, additives were included in example compositions. In particular, additives included a rust and oxidation (R&O) additive package comprising a rust inhibitor, an oxidation inhibitor, and a corrosion inhibitor, as well as a pour point depressant, and an anti-foam additive.TABLE 2Compositions.A-CE-1A-1B-CE-1B-1Composition (mass %)AP / E CORE ™ 250099.095Americas CORE ™ 250074.8Americas CORE ™ 60023.79523.795EHC 340 MAX ™99.09574.8R&O Additive Package0.80.81.01.0Pour Point Depressant0.10.10.40.4Anti-Foam Additive0.0050.0050.0050.005Experiment 2: Oxidation Resistance—Oil Property Measurement (Area A)

[0056] Example lubricant compositions A-CE-1 and A-1 were tested for change in Total Acid Number (TAN) and viscosity increase percentage (%) according to the ExxonMobil Circulating Oil Oxidation Test, performed using the FZG gear test rig. The test was run for 1500 hours at 100° C. with copper and steel catalysts added to the reservoir to make the test more severe. The FZG gears were set to load stage 8 to make the test more severe than a typical circulating oil oxidation test.

[0057] Results of testing are shown in FIGS. 1 and 2, respectively. As shown, Example A-1 maintained stable viscosity increase and virtually no increase in TAN, indicating resistance to oxidation as compared to Comparative Example A-CE-1. The superior oxidation performance of lubricant compositions of the present disclosure is unexpected, since there was no change in the additive packages, and sulfur functions as an antioxidant in Group I oil base stock, such that removal of sulfur by replacement of Group I oil base stock with a Group II extra heavy oil base stock would be expected to degrade oxidation performance.Experiment 3: Oxidation Resistance—Failure Time Measurement (Area B)

[0058] Example lubricant compositions B-CE-1 and B-1 were tested for oxidation time to failure by a Rotating Pressure Vessel Oxidation Test (RPVOT) according to ASTM D2272. Results of testing are shown in FIG. 3. As shown, Example B-1 resisted failure for 450 minutes, significantly longer than the time for Comparative Example B-CE-1 (about 300 minutes). The superior oxidation performance of lubricant compositions of the present disclosure is even more unexpected, for the reasons discussed above.

[0059] Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular examples and configurations disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative examples disclosed above may be altered, combined, or modified and all such variations are considered within the scope and spirit of the present invention. The invention illustratively disclosed herein suitably may be practiced in the absence of any element that is not specifically disclosed herein and / or any optional element disclosed herein. While compositions and methods are described in terms of “comprising,”“containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

[0060] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the present specification and associated claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the incarnations of the present inventions. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claim, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0061] One or more illustrative incarnations incorporating one or more invention elements are presented herein. Not all features of a physical implementation are described or shown in this application for the sake of clarity. It is understood that in the development of a physical embodiment incorporating one or more elements of the present invention, numerous implementation-specific decisions must be made to achieve the developer's goals, such as compliance with system-related, business-related, government-related and other constraints, which vary by implementation and from time to time. While a developer's efforts might be time-consuming, such efforts would be, nevertheless, a routine undertaking for those of ordinary skill in the art and having benefit of this disclosure.

[0062] While compositions and methods are described herein in terms of “comprising” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps.

Examples

examples

[0054]Circulating oils are a specific class of lubricating oils. Circulating oils are lubricating oils for the centralized continuous and reusable lubrication of various systems, to protect critical components such as bearings, blowers, gearboxes, or the like, for a wide range of purposes (e.g., heat exchange, friction reduction, and prevention of wear, corrosion, and rust). Circulating oils operate under conditions of high temperature, exposure to filtration operations, long oil drain intervals, and contact with moisture and other contaminants. Further, circulating oils require exceptional oil life, often tens of thousands of hours. Due to the millions of gallons of these oils used annually, circulating oils must have excellent thermal stability, oxidative stability, filterability, foaming resistance, compatibility with multiple materials, low traction coefficient, low temperature fluidity, and high film thickness at high temperatures. Improved oxidation stability, for example, can...

experiment 1

Formulations

[0055]Example lubricant compositions were formed in two areas, A and B. Example compositions in area A included an API Group II extra heavy oil base stock oil comprising EHC 340 MAX™ (available from Exxon Mobil Corporation) as a first oil base stock. Furthermore, example compositions in area B included an API Group I oil base stock comprising Americas CORE™ 600 (available from Exxon Mobil Corporation) as a second oil base stock in addition to the API Group II extra heavy oil base stock oil comprising EHC 340 MAX™ (available from Exxon Mobil Corporation) as the first oil base stock. Comparative Example compositions in area A included an API Group I bright stock as a comparative example first oil base stock, specifically comprising AP / E CORE™ 2500 (available from Exxon Mobil Corporation) for area A and Americas CORE™ 2500 (available from Exxon Mobil Corporation) for area B. Additionally, additives were included in example compositions. In particular, additives included a r...

experiment 2

Oxidation Resistance—Oil Property Measurement (Area A)

[0056]Example lubricant compositions A-CE-1 and A-1 were tested for change in Total Acid Number (TAN) and viscosity increase percentage (%) according to the ExxonMobil Circulating Oil Oxidation Test, performed using the FZG gear test rig. The test was run for 1500 hours at 100° C. with copper and steel catalysts added to the reservoir to make the test more severe. The FZG gears were set to load stage 8 to make the test more severe than a typical circulating oil oxidation test.

[0057]Results of testing are shown in FIGS. 1 and 2, respectively. As shown, Example A-1 maintained stable viscosity increase and virtually no increase in TAN, indicating resistance to oxidation as compared to Comparative Example A-CE-1. The superior oxidation performance of lubricant compositions of the present disclosure is unexpected, since there was no change in the additive packages, and sulfur functions as an antioxidant in Group I oil base stock, such...

FIELD OF INVENTION

[0001] This application relates to lubricant compositions and methods related thereto.BACKGROUND

[0002] Lubricant compositions (e.g., lubricants, oils, and the like) are used in a variety of mechanical applications for smoothing the operation thereof. Example applications may include internal combustion engines, industrial machinery, gear systems, and the like. Furthermore, lubricant compositions may serve additional roles within desired applications including, but not limited to, cooling machinery, cleansing components, as well as preventing rust and / or corrosion. Lubricant compositions may be subject to various wear and degradation, including oxidation of the lubricant oil itself, leading to reduced lubrication performance.

[0003] A variety of base stocks may be available for formulation of lubricant compositions, including base stocks in American Petroleum Institute (API) groups I through V. The API defines Group I oil base stocks as solvent-refined mineral oils; Group I oil base stocks contain the least saturates and highest amount of sulfur and generally have the lowest viscosity indices. Group I generally defines the bottom tier of lubricant performance. Group II and Group III oil base stocks are high viscosity index and very high viscosity index base stocks, respectively. The Group III oil base stocks generally contain fewer unsaturates and sulfur than the Group II oils. Group IV oil base stocks consist of polyalphaolefins, which are produced via the catalytic oligomerization of linear alphaolefins (LAOs). Group V includes all the other oil base stocks not included in Groups I through IV; Group V base stocks include lubricants based on or derived from esters.SUMMARY OF INVENTION

[0004] According to an embodiment consistent with the present disclosure, lubricant compositions comprise: about 70 wt % to about 99.99 wt % of a first oil base stock, wherein the first oil base stock comprises an API Group II extra heavy oil base stock, the API Group II extra heavy oil base stock having: a kinematic viscosity (ASTM D445, 40° C.) of about 320 cSt to about 520 cSt, a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 36 cSt, a viscosity index (ASTM D2270) of about 80 to about 119, a pour point (ASTM D97) of about −6° C. or less, and a saturate content (ASTM D7419) of about 90 wt % or greater; about 0 wt % to about 30 wt % of a second oil base stock, wherein the second oil base stock comprises an API Group I oil base stock, the API Group I oil base stock having: a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 15 cSt.

[0005] According to another embodiment consistent with the present disclosure, methods for producing a circulating oil composition comprise: optionally, preparing a base oil for a circulating oil composition by blending a first oil base stock for the base oil and a second oil base stock for the base oil, thereby forming the base oil, the base oil comprising: about 70 wt % to about 99.99 wt % of a first oil base stock, wherein the first oil base stock comprises an API Group II extra heavy oil base stock, the API Group II extra heavy oil base stock having: a kinematic viscosity (ASTM D445, 40° C.) of about 320 cSt to about 520 cSt, a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 36 cSt, a viscosity index (ASTM D2270) of about 80 to about 119, a pour point (ASTM D97) of about −6° C. or less, and a saturate content (ASTM D7419) of about 90 wt % or greater; and about 0 wt % to about 30 wt % of a second oil base stock, wherein the second oil base stock comprises an API Group I oil base stock, the API Group I oil base stock having: a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 15 cSt; providing the base oil; optionally, providing an R&O additive package, a pour point depressant, and / or an anti-foam additive; and optionally, blending the base oil with the R&O additive package, the pour point depressant, and / or the anti-foam additive.

[0006] These and other features and attributes of the disclosed compositions and methods of the present disclosure and their advantageous applications and / or uses will be apparent from the detailed description which follows.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawings. The following figures are included to illustrate certain aspects of the disclosure and should not be viewed as exclusive configurations. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure.

[0008] FIG. 1 is a graph of total acid number (TAN) change for example compositions according to the present disclosure.

[0009] FIG. 2 is a graph of viscosity increase for example compositions according to the present disclosure.

[0010] FIG. 3 is a graph of failure time for example compositions according to the present disclosure.DETAILED DESCRIPTION

[0011] This application relates to lubricant compositions and methods related thereto and, particularly, to circulating oil compositions and methods related thereto.

[0012] The term “mass %” as used herein indicates percentage by mass such as percentage by weight (e.g., wt %), “vol %” as used herein indicates percentage by volume, “mol %” as used herein indicates percentage by mole, “ppm” as used herein indicates parts per million, and “ppm wt” and “wppm” are used interchangeably and mean parts per million on a weight basis. All concentrations herein, unless otherwise stated, are expressed on the basis of the total amount of the composition in question.

[0013] The term “polymer” as used herein refers to any two or more of the same or different repeating units / mer unit or units. The term “homopolymer” as used herein refers to a polymer having units that are the same. The term “copolymer” as used herein refers to a polymer having two or more units that are different from each other and includes terpolymers and the like. The term “terpolymer” as used herein refers to a polymer having three units that are different from each other. The term “different” as used herein as it refers to units indicates that the units differ from each other by at least one atom or are different isomerically. Likewise, the definition of polymer, as used herein, includes homopolymers, copolymers, and the like.

[0014] The term “alphaolefin” refers to any linear or branched compound of carbon and hydrogen having at least one double bond between the a and R carbon atoms. For purposes of this specification and the claims appended thereto, when a polymer or copolymer is referred to as including an alpha-olefin (e.g., a polyalphaolefin) the alpha-olefin present in such polymer or copolymer is the polymerized form of the alpha-olefin.

[0015] The term “oil base stock” as used herein refers to any base fluid that could be used in a lubricant including, but not limited to, a terpene, a mineral oil, a synthetic hydrocarbon, an ester, the like, or any combination thereof. An oil base stock as used herein may include Group I, II, III, IV, and V (as defined by American Petroleum Institute [API]) base oils, including any combination thereof. The terms “base oil”, “oil base stock”, “oil basestock,”“basestock oil,”“base stock oil,” simply “base stock,” or any grammatical variations thereof are used interchangeably herein.

[0016] According to the American Petroleum Institute (API) classifications, base stocks are categorized in five groups based on their saturated hydrocarbon content (saturates) (quoted as a weight percent (wt %)), sulfur level (wt %), and viscosity index (see Table 1 below). Lubricant base stocks are typically produced in large scale from petroleum sources. Group I, II, and III base stocks are derived from crude oil via processing, such as solvent extraction, hydroprocessing, solvent or catalytic dewaxing, and hydroisomerization. Group III base stocks also can be produced from synthetic hydrocarbon liquids obtained from natural gas, coal or other fossil resources; Group IV base stocks, the polyalphaolefins (PAO), are produced by oligomerization of alpha olefins, such as 1-decene; Group V base stocks include everything that does not belong to Groups I-IV, such as naphthenics, polyalkylene glycols (PAG), and esters.TABLE 1API Basestock Group Classifications.APIViscosityClassificationwt % Saturateswt % SulfurIndex (VI)Group I<90 and / or>0.03 and≥80 and <120Group II≥90 and≤0.03 and≥80 and <120Group III≥90 and≤0.03 and≥120Group IVPolyalphaolefins (PAO)Group VAll others not in Groups I, II, III, or IV

[0017] Lubricating base oils the present disclosure may be derived from any suitable source. Base stock oils useful in the present disclosure may include natural oils, synthetic oils, and / or unconventional oils (or mixtures thereof). Base stock oils suitable for the present disclosure may be used unrefined, refined, or rerefined (the latter is also known as reclaimed or reprocessed oil). Unrefined oils are those obtained directly from a natural or synthetic source and used without added purification and may include shale oil obtained directly from retorting operations, petroleum oil obtained directly from primary distillation, and ester oil obtained directly from an esterification process. Refined oils are similar to the oils discussed for unrefined oils except refined oils are subjected to one or more purification steps to improve at least one lubricating oil property. One skilled in the art will be familiar with many purification processes. Such purification processes may include solvent extraction, secondary distillation, acid extraction, base extraction, filtration, percolation, and the like. Rerefined oils may be obtained by processes analogous to refined oils but using an oil that has been previously used as a feed stock. Other processes may be used for production of oils of the present disclosure.

[0018] Lubricant compositions of the present disclosure may be suitable lubricants for a variety of applications including, but not limited to, industrial lubricants, automotive lubricants, the like, or any combination thereof. Lubricant composition of the present disclosure may provide increased oxidation resistance, allowing for increased usable lifespan of the lubricant composition and reducing wear and tear on mechanical components surrounding the lubricant compositions.

[0019] Lubricant compositions of the present disclosure may comprise one or more base stocks in combination, including two or more base stocks, such as a first oil base stock and, optionally, a second oil base stock.

[0020] Lubricant compositions of the present disclosure may include the first oil base stock at a concentration of about 60 wt % to about 99.99 wt %, or about 70 wt % to about 99.99 wt %, or about 75 wt % to about 99 wt %, or about 70 wt % to about 80 wt %, or about 98 wt % to about 99.99 wt %, or about 99 wt % to about 99.99 wt %, or about 99.0 wt % to about 99.1 wt %.

[0021] Suitable first oil base stocks may include suitable API Group II base stocks such as group II extra heavy oil base stocks. Group II extra heavy oil base stocks of interest in the present disclosure, may have a kinematic viscosity (ASTM D445, 40° C.) of about 300 centistokes (cSt) to about 600 cSt (or about 320 cSt to about 520 cSt, or about 380 cSt to about 520 cSt, or about 450 cSt to about 520 cSt) and a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 40 cSt (or about 22 cSt to about 36 cSt, or about 27 cSt to about 36 cSt, or about 32 cSt to about 36 cSt). Suitable Group II extra heavy oil base stocks may have a viscosity index (ASTM D2270) of about 80 to about 119 (or about 95 to about 115). Suitable Group II extra heavy oil base stocks may have a pour point (IP 15 or ASTM D97) of about −35° C. to about −6° C. (or about −35° C. to about −15° C., or about −6° C. or less, or about −15° C. or less). Suitable Group II extra heavy oil base stocks may have a saturate content (ASTM D7419) of about 90 wt % or greater (or about 90 wt % to about 99.99 wt %, or about 95 wt % to about 99.99 wt %, or about 98 wt % to about 99.99 wt %, or about 90 wt % to about 99 wt %, or about 95 wt % to about 99 wt %, or about 98 wt % to about 99 wt %, or about 95 wt % or greater, or about 98 wt % or greater, or about 99 wt % or greater). Other characteristics of suitable Group II extra heavy oil base stocks may include, but are not limited to: base stock color (ASTM D6045) of L1.5 to L0.5 (or L1.5 to L1.0, or L1.0 to L0.5); carbon residue (ASTM D4530) of about 0.0001 mass % to about 0.1 mass %, or about 0.001 mass % to about 0.01 mass %, or about 0 mass % to about 0.1 mass %, or about 0 mass % to about 0.01 mass %, or about 0.1 mass % or less, or about 0.01 mass % or less; cloud point (ASTM D2500) of about −60° C. to about −2° C., or about −60° C. to about −30° C., or about −30° C. to about −2° C., or about −2° C. or less, or about −30° C. or less, or about −60° C. or less; flashpoint (ASTM D92) of about 250° C. to about 300° C., or about 250° C. to about 275° C., or about 275° C. to about 300° C., or about 250° C. or greater. Suitable Group II extra heavy oil base stocks for use as a first oil base stock may include those commercially available under the tradenames EHC™ (including, but not limited to, EHC 340 MAX™) (Exxon Mobil Corporation).

[0022] The first oil base stocks may further comprise API Group I bright stocks. The first oil base stocks may include about 1 wt. % to about 20 wt. % of API Group I bright stocks. “Bright stock,” and grammatical variations thereof, as used herein refers to high viscosity API Group I base oils. API Group I bright stocks are more than standard API Group I base oils. API Group I bright stocks may be refined by running feedstock through a vacuum distillation process, followed by solvent extraction, solvent dewaxing, and hydrofinishing processes. Alternatively, API Group I bright stocks may be refined by hydrotreating and catalytic dewaxing of napthenic crude oil. API Suitable API Group I bright stocks may have a kinematic viscosity (ASTM D445, 100° C.) of greater than about 20 cSt to about 40 cSt, or about 25 cSt to about 38 cSt, or about 30 cSt to about 36 cSt. Suitable API Group I bright stocks for use as a first oil base stock may include those commercially available under the tradenames Americas Core 2500 (Exxon Mobil Corporation). The first oil base stocks may include substantially no API Group I bright stocks, including substantially no API Group I bright stocks. “Substantially no,” and grammatical variations thereof, as used herein, refers to a composition including an amount of a compound such that the composition has no discernable properties indicating the presence of the compound, including, but not limited to, for example, less than about 1 wt %, or less than about 0.1 wt %, or less than about 0.01 wt %, or less than about 0.001 wt % of a compound. Lubricant compositions of the present disclosure may use the Group II extra heavy oil base stocks to replace API Group I bright stocks present in corresponding lubricant compositions (e.g., commercially available lubricant oil formulations).

[0023] Lubricant compositions of the present disclosure may optionally include a second oil base stock. Lubricant compositions of the present disclosure may include a second oil base stock at a concentration of about 0 wt % to about 30 wt %, or about 0 wt % to about 1 wt %, or less than about 0.1 wt %, or about 20 wt % to about 25 wt %, or about 20 wt % to about 30 wt %. Suitable second oil base stocks may include API Group I oil base stocks. API Group I oil base stocks may have a kinematic viscosity (ASTM D445, 100° C.) of about 20 cSt or less (e.g., API Group I oil base stocks may exclude API Group I bright stocks). Second oil base stocks may have a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 20, or cSt 2 cSt to about 15 cSt, or about 3 cSt to about 5 cSt, or about 4 cSt to about 6 cSt, or about 10 cSt to about 15 cSt. Suitable second oil base stocks may include, but are not limited to, for example, Americas CORE™ 600 and AP / E CORE™ 600 (Exxon Mobil Corporation).Additives

[0024] Lubricant compositions may include one or more various additive(s) for increasing lubricant performance. Additive(s) included in lubricant compositions of the present disclosure may include, rust and oxidation (R&O) additives, pour point depressants, anti-foam additives, or any combination thereof. R&O additives may include rust inhibitors, oxidation inhibitors, and corrosion inhibitors. R&O additives may be included in lubricant compositions of the present disclosure at concentrations of about 0.1 wt % to about 1.5 wt %, or about 0.1 wt % to about 1.0 wt %, or about 0.5 wt % to about 1.0 wt %. Pour point depressants may be included in lubricant compositions of the present disclosure at concentrations of about 0.01 wt % to about 0.5 wt %, or about 0.05 wt % to about 0.5 wt %, or about 0.05 wt % to about 0.2 wt %. Anti-foam additives may be included in lubricant compositions of the present disclosure at concentrations of about 0.001 wt % to about 0.01 wt %, or about 0.003 wt % to about 0.007 wt %.

[0025] Lubricant additives may include, but are not limited to, for example, dispersants, detergents, antiwear additives, viscosity modifiers, corrosion inhibitors, rust inhibitors, metal deactivators, extreme pressure additives, anti-seizure agents, wax modifiers, fluid-loss additives, seal compatibility agents, friction modifiers, lubricity agents, anti-staining agents, chromophoric agents, defoamants, demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants, and others, including combinations thereof. These additive(s) may be delivered with varying amounts of diluent oil. When lubricant compositions include one or more of the foregoing additive(s), the additive(s) may be blended into the compositions in an amount sufficient to perform an intended function. For example, foregoing additive(s) may each be present in lubricant compositions at concentrations of about 0.001 wt % to about 40 wt %, or about 0.001 wt % to about 10 wt %, or about 0.001 wt % to about 5 wt %.Properties

[0026] Lubricant compositions of the present disclosure may have various properties that may allow for equivalent or increased performance, as compared to corresponding lubricant compositions in the absence of Group II extra heavy oil base stocks. For example, lubricant compositions of the present disclosure may achieve equivalent or increased performance in various properties by using the Group II extra heavy oil base stocks to replace API Group I bright stocks present in corresponding lubricant compositions (e.g., commercially available lubricant formulations).

[0027] Properties of lubricant compositions of the present disclosure may include a viscosity (ASTM D445, 40° C.) from about 400 cSt to about 600 cSt, or about 400 cSt to about 550 cSt, or about 400 cSt to about 525 cSt, or about 400 cSt to about 450 cSt, or about 450 cSt to about 500 cSt. Lubricant compositions of the present disclosure may be of ISO Viscosity Grade (VG) 460.

[0028] Properties of lubricant compositions of the present disclosure may include a Total Acid Number (TAN) change of less than about 0.4, or less than about 0.3, or less than about 0.2, or less than about 0.1, or about 0 to about 0.4, or about 0 to about 0.3, or about 0 to about 0.2, or about 0 to about 0.1, or about 0.01 to about 0.4, or about 0.01 to about 0.3, or about 0.01 to about 0.2, or about 0.01 to about 0.1, during 1500 hours of testing according to an ExxonMobil Circulating Oil Oxidation Test, performed using an FZG gear test rig. The ExxonMobil Circulating Oil Oxidation Test is run for 1500 hours at 100° C. with copper and steel catalysts added to the reservoir to make the test more severe. The FZG gears are set to load stage 8 to make the test more severe than a typical circulating oil oxidation test. Lubricant compositions of the present disclosure may have a TAN change during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test which is about 0.1 lower to about 0.5 lower, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock.

[0029] Properties of lubricant compositions of the present disclosure may include a viscosity increase of less than about 9%, or less than about 8%, or less than about 5%, or less than about 4%, or less than about 3%, or about 0% to about 9%, or about 0% to about 6%, or about 0% to about 4%, or about 0.1% to about 9%, or about 0.1% to about 6%, or about 0.1% to about 4%, or about 1% to about 5%, or about 2% to about 4%, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test using the FZG gear test rig, as described above.

[0030] Lubricant compositions of the present disclosure may have a % viscosity increase during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 2% lower to about a 7% lower, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by one or more API Group I bright stocks.

[0031] Properties of lubricant compositions of the present disclosure may include an oxidation time to failure (ASTM D2272 RPVOT) of greater than 325 minutes, or greater than 350 minutes, or greater than 400 minutes, or greater than 450 minutes, or 325 minutes to 500 minutes, or 325 minutes to 475 minutes, or 325 minutes to 450 minutes, or 400 minutes to 800 minutes, or 400 minutes to 700 minutes, or 400 minutes to 600 minutes, or 400 minutes to 500 minutes, or 450 minutes to 475 minutes. Lubricant compositions of the present disclosure may have an oxidation time to failure (ASTM D2272 RPVOT) which is about 90 minutes or greater to about 160 minutes or greater, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock.

[0032] Furthermore, lubricant compositions of the present disclosure may have a reduced sulfur content (ASTM D6443), as compared to corresponding lubricant compositions in the absence of (e.g., where bright stocks take the place of) the Group II extra heavy oil base stock, without a corresponding decrease in oxidation performance.ADDITIONAL EMBODIMENTS

[0033] Embodiment 1. A lubricant composition comprising: about 70 wt % to about 99.99 wt % of a first oil base stock, wherein the first oil base stock comprises an API Group II extra heavy oil base stock, the API Group II extra heavy oil base stock having: a kinematic viscosity (ASTM D445, 40° C.) of about 320 cSt to about 520 cSt, a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 36 cSt, a viscosity index (ASTM D2270) of about 80 to about 119, a pour point (ASTM D97) of about −6° C. or less, and a saturate content (ASTM D7419) of about 90 wt % or greater; about 0 wt % to about 30 wt % of a second oil base stock, wherein the second oil base stock comprises an API Group I oil base stock, the API Group I oil base stock having: a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 15 cSt.

[0034] Embodiment 2. The lubricant composition of Embodiment 1, wherein the lubricant composition comprises about 0 wt % of the second oil base stock.

[0035] Embodiment 3. The lubricant composition of Embodiment 1, wherein the lubricant composition comprises about 20 wt % to about 30 wt % of the second oil base stock.

[0036] Embodiment 4. The lubricant composition of any one of Embodiments 1-3, wherein the first oil base stock comprises less than about 1 weight percent (wt. %) of an API Group I bright stock.

[0037] Embodiment 5. The lubricant composition of any one of Embodiments 1-4, further comprising: about 0.1 wt % to about 1.5 wt % of a R&O additive package, the R&O additive package comprising a rust inhibitor, an oxidation inhibitor, and a corrosion inhibitor; about 0.05 wt % to about 0.5 wt % of a pour point depressant; and / or about 0.001 wt % to about 0.01 wt % of an anti-foam additive.

[0038] Embodiment 6. The lubricant composition of any one of Embodiments 1-5, wherein the lubricant composition has a TAN change of less than about 0.2 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

[0039] Embodiment 7. The lubricant composition of any one of Embodiments 1-6, wherein the lubricant composition has a % viscosity increase of less than about 5 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

[0040] Embodiment 8. The lubricant composition of any one of Embodiment 1-7, wherein the lubricant composition has an oxidation time to failure (ASTM D2272 RPVOT) of about 400 minutes to about 800 minutes.

[0041] Embodiment 9. The lubricant composition of any one of Embodiments 1-8, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock: a TAN change, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 0.1 lower to about 0.5 lower; and / or a % viscosity increase, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 2% lower to about a 7% lower.

[0042] Embodiment 10. The lubricant composition of any one of Embodiments 1-9, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock: an oxidation time to failure (ASTM D2272 RPVOT) which is about 90 minutes greater to about 160 minutes greater.

[0043] Embodiment 11. A method for producing a circulating oil composition, the method comprising: optionally, preparing a base oil for a circulating oil composition by blending a first oil base stock for the base oil and a second oil base stock for the base oil, thereby forming the base oil, the base oil comprising: about 70 wt % to about 99.99 wt % of a first oil base stock, wherein the first oil base stock comprises an API Group II extra heavy oil base stock, the API Group II extra heavy oil base stock having: a kinematic viscosity (ASTM D445, 40° C.) of about 320 cSt to about 520 cSt, a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 36 cSt, a viscosity index (ASTM D2270) of about 80 to about 119, a pour point (ASTM D97) of about −6° C. or less, and a saturate content (ASTM D7419) of about 90 wt % or greater; and about 0 wt % to about 30 wt % of a second oil base stock, wherein the second oil base stock comprises an API Group I oil base stock, the API Group I oil base stock having: a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 15 cSt; providing the base oil; optionally, providing an R&O additive package, a pour point depressant, and / or an anti-foam additive; and optionally, blending the base oil with the R&O additive package, the pour point depressant, and / or the anti-foam additive.

[0044] Embodiment 12. The method of Embodiment 11, wherein the lubricant composition comprises about 0 wt % of the second oil base stock.

[0045] Embodiment 13. The method of Embodiment 11, wherein the lubricant composition comprises about 20 wt % to about 30 wt % of the second oil base stock.

[0046] Embodiment 14. The method of any one of Embodiments 11-13, wherein the first oil base stock replaces comprises less than about 1 weight percent (wt. %) of an API Group I bright stock.

[0047] Embodiment 15. The method of any one of Embodiments 11-14, further comprising: about 0.1 wt % to about 1.5 wt % of a R&O additive package, the R&O additive package comprising a rust inhibitor, an oxidation inhibitor, and a corrosion inhibitor; about 0.05 wt % to about 0.5 wt % of a pour point depressant; and / or about 0.001 wt % to about 0.01 wt % of an anti-foam additive

[0048] Embodiment 16. The method of any one of Embodiments 11-15, wherein the lubricant composition has a TAN change of less than 0.2 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

[0049] Embodiment 17. The method of any one of Embodiments 11-16, wherein the lubricant composition has a % viscosity increase of less than 5 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

[0050] Embodiment 18. The method of any one of Embodiments 11-17, wherein the lubricant composition has an oxidation time to failure (ASTM D2272 RPVOT) of 400 minutes to 800 minutes.

[0051] Embodiment 19. The method of any one of Embodiments 11-18, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock: a TAN change, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 0.1 lower to about 0.5 lower; and / or a % viscosity increase, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 2% lower to about a 7% lower.

[0052] Embodiment 20. The method of any one of Embodiments 11-19, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock: an oxidation time to failure (ASTM D2272 RPVOT) which is about 90 minutes greater to about 160 minutes greater.

[0053] To facilitate a better understanding of the embodiments of the present invention, the following examples of preferred or representative embodiments are given. In no way should the following examples be read to limit, or to define, the scope of the invention.EXAMPLES

[0054] Circulating oils are a specific class of lubricating oils. Circulating oils are lubricating oils for the centralized continuous and reusable lubrication of various systems, to protect critical components such as bearings, blowers, gearboxes, or the like, for a wide range of purposes (e.g., heat exchange, friction reduction, and prevention of wear, corrosion, and rust). Circulating oils operate under conditions of high temperature, exposure to filtration operations, long oil drain intervals, and contact with moisture and other contaminants. Further, circulating oils require exceptional oil life, often tens of thousands of hours. Due to the millions of gallons of these oils used annually, circulating oils must have excellent thermal stability, oxidative stability, filterability, foaming resistance, compatibility with multiple materials, low traction coefficient, low temperature fluidity, and high film thickness at high temperatures. Improved oxidation stability, for example, can lead to longer oil life in severe oil service.Experiment 1: Formulations

[0055] Example lubricant compositions were formed in two areas, A and B. Example compositions in area A included an API Group II extra heavy oil base stock oil comprising EHC 340 MAX™ (available from Exxon Mobil Corporation) as a first oil base stock. Furthermore, example compositions in area B included an API Group I oil base stock comprising Americas CORE™ 600 (available from Exxon Mobil Corporation) as a second oil base stock in addition to the API Group II extra heavy oil base stock oil comprising EHC 340 MAX™ (available from Exxon Mobil Corporation) as the first oil base stock. Comparative Example compositions in area A included an API Group I bright stock as a comparative example first oil base stock, specifically comprising AP / E CORE™ 2500 (available from Exxon Mobil Corporation) for area A and Americas CORE™ 2500 (available from Exxon Mobil Corporation) for area B. Additionally, additives were included in example compositions. In particular, additives included a rust and oxidation (R&O) additive package comprising a rust inhibitor, an oxidation inhibitor, and a corrosion inhibitor, as well as a pour point depressant, and an anti-foam additive.TABLE 2Compositions.A-CE-1A-1B-CE-1B-1Composition (mass %)AP / E CORE ™ 250099.095Americas CORE ™ 250074.8Americas CORE ™ 60023.79523.795EHC 340 MAX ™99.09574.8R&O Additive Package0.80.81.01.0Pour Point Depressant0.10.10.40.4Anti-Foam Additive0.0050.0050.0050.005Experiment 2: Oxidation Resistance—Oil Property Measurement (Area A)

[0056] Example lubricant compositions A-CE-1 and A-1 were tested for change in Total Acid Number (TAN) and viscosity increase percentage (%) according to the ExxonMobil Circulating Oil Oxidation Test, performed using the FZG gear test rig. The test was run for 1500 hours at 100° C. with copper and steel catalysts added to the reservoir to make the test more severe. The FZG gears were set to load stage 8 to make the test more severe than a typical circulating oil oxidation test.

[0057] Results of testing are shown in FIGS. 1 and 2, respectively. As shown, Example A-1 maintained stable viscosity increase and virtually no increase in TAN, indicating resistance to oxidation as compared to Comparative Example A-CE-1. The superior oxidation performance of lubricant compositions of the present disclosure is unexpected, since there was no change in the additive packages, and sulfur functions as an antioxidant in Group I oil base stock, such that removal of sulfur by replacement of Group I oil base stock with a Group II extra heavy oil base stock would be expected to degrade oxidation performance.Experiment 3: Oxidation Resistance—Failure Time Measurement (Area B)

[0058] Example lubricant compositions B-CE-1 and B-1 were tested for oxidation time to failure by a Rotating Pressure Vessel Oxidation Test (RPVOT) according to ASTM D2272. Results of testing are shown in FIG. 3. As shown, Example B-1 resisted failure for 450 minutes, significantly longer than the time for Comparative Example B-CE-1 (about 300 minutes). The superior oxidation performance of lubricant compositions of the present disclosure is even more unexpected, for the reasons discussed above.

[0059] Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular examples and configurations disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative examples disclosed above may be altered, combined, or modified and all such variations are considered within the scope and spirit of the present invention. The invention illustratively disclosed herein suitably may be practiced in the absence of any element that is not specifically disclosed herein and / or any optional element disclosed herein. While compositions and methods are described in terms of “comprising,”“containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

[0060] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the present specification and associated claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the incarnations of the present inventions. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claim, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0061] One or more illustrative incarnations incorporating one or more invention elements are presented herein. Not all features of a physical implementation are described or shown in this application for the sake of clarity. It is understood that in the development of a physical embodiment incorporating one or more elements of the present invention, numerous implementation-specific decisions must be made to achieve the developer's goals, such as compliance with system-related, business-related, government-related and other constraints, which vary by implementation and from time to time. While a developer's efforts might be time-consuming, such efforts would be, nevertheless, a routine undertaking for those of ordinary skill in the art and having benefit of this disclosure.

[0062] While compositions and methods are described herein in terms of “comprising” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps.

Examples

examples

[0054]Circulating oils are a specific class of lubricating oils. Circulating oils are lubricating oils for the centralized continuous and reusable lubrication of various systems, to protect critical components such as bearings, blowers, gearboxes, or the like, for a wide range of purposes (e.g., heat exchange, friction reduction, and prevention of wear, corrosion, and rust). Circulating oils operate under conditions of high temperature, exposure to filtration operations, long oil drain intervals, and contact with moisture and other contaminants. Further, circulating oils require exceptional oil life, often tens of thousands of hours. Due to the millions of gallons of these oils used annually, circulating oils must have excellent thermal stability, oxidative stability, filterability, foaming resistance, compatibility with multiple materials, low traction coefficient, low temperature fluidity, and high film thickness at high temperatures. Improved oxidation stability, for example, can...

experiment 1

Formulations

[0055]Example lubricant compositions were formed in two areas, A and B. Example compositions in area A included an API Group II extra heavy oil base stock oil comprising EHC 340 MAX™ (available from Exxon Mobil Corporation) as a first oil base stock. Furthermore, example compositions in area B included an API Group I oil base stock comprising Americas CORE™ 600 (available from Exxon Mobil Corporation) as a second oil base stock in addition to the API Group II extra heavy oil base stock oil comprising EHC 340 MAX™ (available from Exxon Mobil Corporation) as the first oil base stock. Comparative Example compositions in area A included an API Group I bright stock as a comparative example first oil base stock, specifically comprising AP / E CORE™ 2500 (available from Exxon Mobil Corporation) for area A and Americas CORE™ 2500 (available from Exxon Mobil Corporation) for area B. Additionally, additives were included in example compositions. In particular, additives included a r...

experiment 2

Oxidation Resistance—Oil Property Measurement (Area A)

[0056]Example lubricant compositions A-CE-1 and A-1 were tested for change in Total Acid Number (TAN) and viscosity increase percentage (%) according to the ExxonMobil Circulating Oil Oxidation Test, performed using the FZG gear test rig. The test was run for 1500 hours at 100° C. with copper and steel catalysts added to the reservoir to make the test more severe. The FZG gears were set to load stage 8 to make the test more severe than a typical circulating oil oxidation test.

[0057]Results of testing are shown in FIGS. 1 and 2, respectively. As shown, Example A-1 maintained stable viscosity increase and virtually no increase in TAN, indicating resistance to oxidation as compared to Comparative Example A-CE-1. The superior oxidation performance of lubricant compositions of the present disclosure is unexpected, since there was no change in the additive packages, and sulfur functions as an antioxidant in Group I oil base stock, such...

Claims

1. A lubricant composition comprising:about 70 wt % to about 99.99 wt % of a first oil base stock, wherein the first oil base stock comprises an API Group II extra heavy oil base stock, the API Group II extra heavy oil base stock having:a kinematic viscosity (ASTM D445, 40° C.) of about 320 cSt to about 520 cSt,a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 36 cSt,a viscosity index (ASTM D2270) of about 80 to about 119,a pour point (ASTM D97) of about −6° C. or less, anda saturate content (ASTM D7419) of about 90 wt % or greater;about 0 wt % to about 30 wt % of a second oil base stock, wherein the second oil base stock comprises an API Group I oil base stock, the API Group I oil base stock having:a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 15 cSt.

2. The lubricant composition of claim 1, wherein the lubricant composition comprises about 0 wt % of the second oil base stock.

3. The lubricant composition of claim 1, wherein the lubricant composition comprises about 20 wt % to about 30 wt % of the second oil base stock.

4. The lubricant composition of claim 1, wherein the first oil base stock comprises less than about 1 weight percent (wt. %) of an API Group I bright stock.

5. The lubricant composition of claim 1, further comprising:about 0.1 wt % to about 1.5 wt % of a R&O additive package, the R&O additive package comprising a rust inhibitor, an oxidation inhibitor, and a corrosion inhibitor;about 0.05 wt % to about 0.5 wt % of a pour point depressant; and / orabout 0.001 wt % to about 0.01 wt % of an anti-foam additive.

6. The lubricant composition of claim 1, wherein the lubricant composition has a TAN change of less than about 0.2 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

7. The lubricant composition of claim 1, wherein the lubricant composition has a % viscosity increase of less than about 5 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

8. The lubricant composition of claim 1, wherein the lubricant composition has an oxidation time to failure (ASTM D2272 RPVOT) of about 400 minutes to about 800 minutes.

9. The lubricant composition of claim 1, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock:a TAN change, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 0.1 lower to about 0.5 lower; and / ora % viscosity increase, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 2% lower to about a 7% lower.

10. The lubricant composition of claim 1, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock:an oxidation time to failure (ASTM D2272 RPVOT) which is about 90 minutes greater to about 160 minutes greater.

11. A method for producing a circulating oil composition, the method comprising:optionally, preparing a base oil for a circulating oil composition by blending a first oil base stock for the base oil and a second oil base stock for the base oil, thereby forming the base oil, the base oil comprising:about 70 wt % to about 99.99 wt % of a first oil base stock, wherein the first oil base stock comprises an API Group II extra heavy oil base stock, the API Group II extra heavy oil base stock having:a kinematic viscosity (ASTM D445, 40° C.) of about 320 cSt to about 520 cSt,a kinematic viscosity (ASTM D445, 100° C.) of about 22 cSt to about 36 cSt,a viscosity index (ASTM D2270) of about 80 to about 119,a pour point (ASTM D97) of about −6° C. or less, anda saturate content (ASTM D7419) of about 90 wt % or greater; andabout 0 wt % to about 30 wt % of a second oil base stock, wherein the second oil base stock comprises an API Group I oil base stock, the API Group I oil base stock having:a kinematic viscosity (ASTM D445, 100° C.) of about 2 cSt to about 15 cSt;providing the base oil;optionally, providing an R&O additive package, a pour point depressant, and / or an anti-foam additive; andoptionally, blending the base oil with the R&O additive package, the pour point depressant, and / or the anti-foam additive.

12. The method of claim 11, wherein the lubricant composition comprises about 0 wt % of the second oil base stock.

13. The method of claim 11, wherein the lubricant composition comprises about 20 wt % to about 30 wt % of the second oil base stock.

14. The method of claim 11, wherein the first oil base stock replaces comprises less than about 1 weight percent (wt. %) of an API Group I bright stock.

15. The method of claim 11, further comprising:about 0.1 wt % to about 1.5 wt % of a R&O additive package, the R&O additive package comprising a rust inhibitor, an oxidation inhibitor, and a corrosion inhibitor;about 0.05 wt % to about 0.5 wt % of a pour point depressant; and / orabout 0.001 wt % to about 0.01 wt % of an anti-foam additive.

16. The method of claim 11, wherein the lubricant composition has a TAN change of less than 0.2 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

17. The method of claim 11, wherein the lubricant composition has a % viscosity increase of less than 5 during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test.

18. The method of claim 11, wherein the lubricant composition has an oxidation time to failure (ASTM D2272 RPVOT) of 400 minutes to 800 minutes.

19. The method of claim 11, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock:a TAN change, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 0.1 lower to about 0.5 lower; and / ora % viscosity increase, during 1500 hours of testing according to the ExxonMobil Circulating Oil Oxidation Test, which is about 2% lower to about a 7% lower.

20. The method of claim 11, wherein the lubricant composition has, as compared to a corresponding lubricant composition wherein the Group II extra heavy oil base stock is replaced by an API Group I bright stock:an oxidation time to failure (ASTM D2272 RPVOT) which is about 90 minutes greater to about 160 minutes greater.

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