Abstract: The present disclosure relates to a non-acidic, sulfur-containing, phosphorus-containing compound of the formula I where R1, R2, R3, R4, R5, R6, and R7 are as defined herein. Such a compound may exhibit improved antiwear performance and thermal stability in lubricating compositions.

Abstract: A lubrication-condition detector detects a lubricant shortage of a target portion that repeats a predetermined operation at a predetermined cycle. The lubrication-condition detector includes: a physical-quantity measuring unit for continuously measuring a physical quantity related to the target portion; and a computer for determining a presence of a lubricant shortage based on the physical quantity. The computer includes: a cycle extractor for extracting a cycle datum per an operational cycle from continuous data including the physical quantity and its measuring time; a representative-value calculator for calculating a representative value for each of plural cycle data; and determining unit for determining a presence of a lubricant shortage based on the plural representative values.

Abstract: A method for forming a finished lubricant comprises selecting a target high temperature viscosity for the finished lubricant. A target high temperature viscosity for a base oil blend is selected. The target high temperature viscosity for the base oil blend is less than the target high temperature viscosity for the finished lubricant. At least two base oils from at least three viscosity grades of base oils are selected and mixed to form a base oil blend that meets the target high temperature viscosity for the base oil blend. The base oil blend is mixed with performance additive package and viscosity modifier to provide a finished lubricant that meets the target high temperature viscosity for the finished lubricant. The at least two base oils for the base oil blend having the target high temperature viscosity are selected such that less viscosity modifier is needed to meet the target high temperature viscosity of the finished lubricant.

Abstract: An apparatus having a vacuum vessel that has a mechanism using a lubricant therein and not causing defects and faults to samples introduced into the vacuum vessel even it is an apparatus where lubricating oil or grease is applied is provided. An apparatus having a vacuum vessel that has a mechanism using a lubricant therein such as CD-SEM, in which a lubricant (oil, grease) whose adsorption amount per minute to a surface of a material introduced into the vacuum vessel of an apparatus for evaluating a lubricant after the start of vacuum evacuation and after reaches a quasi-equilibrium state is below 0.09 ng/cm2 is employed.

Abstract: A lubricant deterioration detecting device includes an arcuate optical fiber having one end positioned in face-to-face relation with a light emitting element and also having the opposite end positioned in face-to-face relation with a light receiving element, and a measuring gap for intervening a lubricating agent is provided in a portion of the arcuate optical fiber. In the vicinity of the measuring gap, a resistance element, the amount of deformation of which varies with change in state of lubrication performed with the lubricating agent, is provided for flowing of the lubricating agent within the measuring gap.

Abstract: An apparatus and a method for detection of wear particles in a lubricant are disclosed. The apparatus includes a microfluidic device including a microchannel sized for a lubricant containing wear particles to pass therethrough and first and second electrodes extending into the microchannel. A detection system is coupled with the electrodes for detection of wear particles passing through the microchannel, based on a change in capacitance of the electrodes.

Abstract: Systems and methods for testing an engine lubricant are provided. The system includes a test assembly rotatably supportable on a platform. The test assembly includes a pair of spaced apart blocks and at least one test cylinder. The blocks include a support block and a test block. The support block has at least one cavity therein. The test block has a heat source applying heat to a test surface thereof. The test cylinder has the engine lubricant therein, and a closed end and an open end opposite thereto. The closed end is positionable in the cavity of the support block. The open end is positionable adjacent the test surface of the test block. The test cylinder is rotatable between a contact position and a non-contact position by the rotating frame such that the engine lubricant is selectively contactable with the test surface whereby deposits form on the test surface.

Abstract: Disclosed in certain embodiments is a method of determining the individual concentration of different antioxidants of the same class in a sample comprising contacting the sample with an effective amount of phenol; and analyzing the sample by voltammetry.

Abstract: Process for evaluating the effect of a refinery feedstock on a refinery process by (i) providing a refinery feedstock (ii) treating the refinery feedstock to produce a plurality of fractions each representative of a feedstock for the refinery process, the plurality of fractions having at least two fractions with different properties; (iii) treating each of the plurality of fractions under experimental conditions representative of those in the refinery process, the treatments being carried out in an essentially parallel manner; and (iv) determining one or more performance criteria for each fraction for the refinery process by analyzing the respective product streams produced from each fraction at least partially in parallel.

Abstract: A method for evaluating antifoam additives for lubricants. The method includes a step of aging a quantity of fluid containing an antifoam additive in one or more high shear simulator(s) for a period of time to provide an aged fluid. After the aging step, the fluid is evaluated in a foam tendency evaluation test to provide the foaming tendency for the fluid.

Abstract: A kit for testing grease includes components for testing consistency, oil bleed characteristic and contamination. Consistency of the grease is tested by compressing a sample of the grease between two surfaces (e.g., glass plates), measuring the extent of spread, and comparing the measured spread to a calibrated reference. Oil bleed characteristic is tested by placing a quantity of the used grease on a test medium, heating the test sample, measuring a dimension of the grease quantity on the heated test sample, and determining the bleed characteristic of the used grease by comparing the dimension of the grease quantity to a reference. A contamination test may be performed by further compressing the consistency sample and inspecting the sample both by the naked eye and with a microscope.

Abstract: The present disclosure relates to a non-acidic, sulfur-containing, phosphorus-containing compound of the formula I where R1, R2, R3, R4, R5, R6, and R7 are as defined herein. Such a compound may exhibit improved antiwear performance and thermal stability in lubricating compositions.

Abstract: An apparatus for measuring air amount of engine oil includes an inflow pipe in which the engine oil flows in connection with an engine and an inflow valve, a measuring burette having an inflow hole connected with the inflow pipe and an outflow hole formed at the other side and a measurement camera provided at the side of the measuring burette to photograph graduations, a vent pipe branched from the outflow hole of the measuring burette and a bent valve provided on the vent pipe, a drain burette having a drain pipe connected with the outflow hole provided at one side thereof and having a drain valve provided on the drain pipe, an auxiliary drain pipe having one side branched from the inflow hole and the other side connected to the drain burette and an auxiliary valve provided on the auxiliary drain pipe, and a control unit.

Abstract: A method and device for determining the appropriate time to recharge hydraulic fluid in a work vehicle. The method preferably includes making a real time determination of the at least a quality parameter of hydraulic fluid in a work vehicle. The system includes comparing in real time, the quality parameter to a predetermined value for the hydraulic fluid. The method of the present invention also includes a system for comparing the determined values and communicating same to an operator. The method of the present invention also includes the capacity to control the output level of the work vehicle according to the level of contamination in the hydraulic fluid. The present invention also provides a device for real time monitoring and control of the hydraulic fluid.

Abstract: The present invention relates to a method of measuring engine oil deterioration, including measuring the first absorbance of engine oil using near infrared at a wavelength of 1000 nm or more, measuring the second absorbance of the engine oil during use using near infrared at the wavelength, and comparing the first absorbance and the second absorbance of the engine oil, so that the engine oil may be determined to be in a state of deterioration when the second absorbance may be at least 1.5 times the first absorbance, and to a system for measuring engine oil deterioration therefor.

Abstract: In a method for determining a total hydrocarbon composition of a multiphase flow including gas and liquid, the method includes taking different samples of the gas and liquid at t least two different thermodynamic states of the multiphase flow. The method further includes analyzing the different samples, and using a molar balance of the different samples at the at least two different thermodynamic states to calculate a gas molar fraction and a liquid molar fraction. The gas molar fraction and liquid molar fraction may be used for deriving an overall composition of the multiphase flow and for deriving the gas and liquid volume fractions.

Abstract: A method and apparatus for determining oil degradation measures a first electric-current value of a driving current used to operate an electric oil pump at a predetermined consistent revolution, and stores the first electric-current value as an electric-current initial value. Data is corrected by measuring a second electric-current value of the driving current, with the second electric-current value being measured when the electric pump is operated at the predetermined consistent revolution when the engine is driven a predetermined time after the electric-current initial value is stored. The electric-current initial value is compared with the second electric-current value. It is then determined that a viscosity of the oil has become low when a difference between the electric-current initial value and the second electric-current value is equal to or greater than a predetermined value.

Abstract: A capacitive sensor in its simplest form has three identical plated spatial electrodes, which are positioned equally spaced apart, in order, alignment and parallel with each other. The first and third electrodes are the outer electrodes and connected in parallel by a first lead wire serving as a first electrical pole to be a group of the integrated electrodes. The second electrode is the middle electrode and connected by a second lead wire serving as a second electrical pole. The sensor is applied with an alternating current (AC) excitation signal from an AC device. The present invention method includes application of referencing and sensing capacitive sensors to obtain a measured temperature compensated electrical property of the oil to thereby obtain a measured remaining usage so as to a predicted remaining usage of the oil.

Abstract: Techniques for determining viscosity of oil in a sample include extracting the oil from the sample using a volatile polar first solvent; using a portion of the extracted oil to determine a concentration factor of oil in the sample; determining a dry weight of the extracted oil using the concentration factor; adding a second solvent to a remaining portion of the extract, where the second solvent is less volatile than the first solvent; removing the first solvent from the remaining portion of the extract; taking a series of sub-samples from the remaining portion of the extract and sequentially removing different amounts of the second solvent from each sub-sample; measuring solvent concentrations and viscosity values of the solvent-oil mixtures of each sub-sample; and based on the measured solvent concentrations and viscosity values of each sub-sample, determining the second-solvent-free viscosity of the oil in the sample.

Abstract: A tubular filter suitable for capturing and removing, in a continuous production line, solid content and oil content in a large volume of liquid (particularly a beverage liquid). A tubular liquid-treating filter formed by winding a nonwoven fabric layer together with a reinforcing net sheet, wherein the reinforcing net sheet has a mesh size in the range from 6 to 35 mesh and includes a portion having a thickness in the range from 0.3 to 2.0 mm.

Abstract: The disclosure presents an apparatus and method for measuring viscosity of a lubricating oil. The apparatus has a piezo-resistive cantilever sensor for sensing a first oil viscosity parameter. The sensor has a cantilever having a pressure receiving portion for receiving pressure exerted by the lubricating oil as the lubricating oil comes into contact with the pressure receiving portion. The cantilever also has first and second resistive portions in electrical communication with a first lead and a second lead, respectively, which are in electrical communication with an electrical circuit amplification element, for creating an output signal indicative of a change in the resistive characteristics of the first and second resistive portions of the cantilever as the lubricating oil comes into contact with the pressure receiving portion. The output signal can be used for determining oil viscosity.

Abstract: Disclosed in certain embodiments is a method of determining the individual concentration of different antioxidants of the same class in a sample comprising contacting the sample with an effective amount of phenol; and analyzing the sample by voltammetry.

Abstract: The invention relates to a housing part containing a lubricant reservoir and at least one respective inlet and outlet opening for filling and draining a lubricating fluid into and from the lubricant reservoir. The inlet and outlet openings are sealed by releasable closure devices each comprising a sensor means for determining the operation parameters in a lubricant contained in the lubricant reservoir and for generating and/or storing sensor signals, as well as a transceiver for the transmission of the sensor signals to an external processing unit.

Abstract: The quantitative determination of aging effects on motor oil is of great interest. According to a method, two variables of the motor oil are detected, one of the two variables being the viscosity and the other variable being the acid content of the motor oil. A first deviation of the detected first variable from a default value is then determined, and the second variable is estimated based on the deviation. By determining a second deviation of the estimated second variable from the detected second variable, the second deviation is determined as a measure of the aging effect on the motor oil. Since various aging effects influence the two variables in different manners, individual aging effects may be quantitatively determined in a targeted manner.

Abstract: In a fuel property sensor, a pair of first and second electrodes is arranged in a fuel chamber to measure an electric capacitance, thereby detecting a mixing ratio of alcohol to gasoline in a fuel of the fuel chamber. An outer wall surface of the first electrode is exposed in the fuel, and a sensing portion contacts an inner wall surface of the first electrode to detect a temperature of the fluid via the first electrode. One end portion of a lead is connected to the sensing portion and the other end portion thereof is connected to a plate portion attached to a housing. Furthermore, an elastic deformation portion is provided as a part of the lead to be elastically deformed, and to cause the sensing portion to be biased in a direction on which the sensing portion contacts the inner wall surface of the first electrode.

Abstract: The invention relates to a bearing, comprising: a first and a second bearing element (11, 13, 17, 12, 14, 18) that are movable relative to one another; a lubricant (2) arranged between the first and the second bearing element (11, 13, 17, 12, 14, 18) for reducing the friction between the first and the second bearing element; at least one transmitter (3) for exciting acoustic waves (A, A1, A2) in the first or the second bearing element (11, 13, 17, 12, 14, 18), the transmitter (3) being arranged on the first or the second bearing element; at least one receiver (4) for receiving acoustic waves evoked by the transmitter (3), the receiver (4) being arranged on the first or the second bearing element (11, 13, 17, 12, 14, 18), wherein information related to properties of the lubricant (2) can be determined using a signal generated by the receiver (4) upon receipt of acoustic waves evoked by the transmitter (3). The invention is also related to a method for determining properties of a lubricant in a bearing.

Abstract: An engine oil system comprises an oil condition sensing device and a control module. The oil condition sensing device includes an electrically actuated member and is in fluid communication with an engine oil reservoir. The control module selectively causes current to be supplied to the oil condition sensing device to actuate the member, measures the current, determines a parameter of the current, and selectively identifies at least two of an oil level, an oil change event, and an oil viscosity level based on the parameter.

Abstract: A method and control module for indicating engine oil life includes a viscosity determination module determining a viscosity of the engine oil based on an engine oil pressure and engine oil temperature. The control system further includes a comparison module comparing the viscosity of the engine oil to a threshold and generating a warning signal in response to comparing the viscosity.

Abstract: The present disclosure provides a method for detecting degradation of an engine oil, by separation into a polar component and a non-polar component via admixture with a polar solvent having a polarity index greater than or equal to 5 and optionally a non-polar solvent having a polarity index of less than or equal to about 1. The polar component is analyzed for one or more degradation indicators selected from the group consisting of antioxidants, acid content, and combinations thereof. Such degradation indicators relate to a degree of engine oil degradation. The polar component may be analyzed by Gas Chromatography and Mass Spectrometry (GC/MS) for the one or more degradation indicators, which can provide a semi-quantitative level of such degradation indicator species. The non-polar component identifies combustion products that help to explain the level of degradation.

Abstract: This invention is a method for determining the quality of lubrication oil added to a quantity of used oil in an operating engine or mechanism such as occurs during an oil change or when additional oil is added to maintain the vehicle manufacturer's specified total volume of oil. The method is based on identifying the electrical resistivity characteristics of the oil addition, representative of both the base oil formulation and its additive package, and, through comparison with previously-generated resistivity data on multiple oils identifying the oil addition. The added oil may then be compared with manufacturer specifications for the specific application to determine whether it meets recommended manufacturer requirements.

Abstract: The invention relates to a method for metered dispensing of lubricants using a lubricant dispenser comprising a reservoir chamber filled with lubricant, a gas generating unit for electrochemically generating gas, a piston acted on by the generated gas for outputting the lubricant from the reservoir chamber, and an electronic control unit for controlling the electrochemical gas generation. According to the invention, the temperature of the lubricant or the environment is measured at time intervals, and an average temperature value is derived from a plurality of measured temperature values. Using stored correction values describing the temperature-dependence of the electrochemical gas generating rate, a control parameter determining the electrochemical gas generation is set for the average temperature value, having the requirement that the gas generating rate at the average temperature value corresponds to the target value that correlates to prescribed dispensing time.

Abstract: An improved method for predicting the remaining useful life of transmission oil and an apparatus for practicing the same are provided. The method includes: detecting if the transmission has completed a new shift; if yes, determining a total shift count; determining accumulated distance and accumulated time parameters; determining a transmission temperature degradation factor; detecting if the lockup clutch is open and if the transmission is in range; if yes, determining a converter degradation factor; determining a total degradation factor based at least in part upon the transmission temperature degradation factor and converter degradation factor; determining an oil life time limit and oil life distance limit; determining if either the accumulated time parameter is greater than the oil life time limit or the accumulated distance parameter is greater than the oil life distance limit; if yes, activating a service indicator to notify vehicle occupants that transmission oil service is required.

Abstract: A method for monitoring a linear guide with a carriage that can be displaced along a rail on a lubricated rolling contact is provided having a sensor device for detecting a state of a lubricant for lubricating the rolling contact. In order to allow a quick determination of the state of the lubricant with simple measures, an oscillation time signal is detected by a sensor device from which a characteristic value that increases with increasing degradation of the lubricant is determined by an effective value determination after high-pass filtering. When the characteristic value exceeds a specified threshold value, measures are initiated for improving the lubricating properties.

Abstract: A vehicle working-fluid evaluating system includes an obtaining device configured to obtain a plurality of deterioration elements related to deterioration factors that are generated as a vehicle travels and that accelerate deterioration of working fluid. A deterioration-level calculator is configured to calculate, based on the plurality of deterioration elements obtained by the obtaining device, an oil deterioration estimate. A severity determining device is configured to determine, in accordance with the oil deterioration estimate calculated by the deterioration-level calculator, severity of usage of the working fluid for a transmission mounted on the vehicle. A change-timing determining device is configured to determine the working-fluid change timing in accordance with the severity of usage of the working fluid determined by the severity determining device. A notification device is configured to indicate the determined working-fluid change timing determined by the change-timing determining device.

Abstract: A method for identifying a lubricant composition that reduces the propensity for knock in an engine. The lubricant composition is mixed with a solvent to reduce the viscosity of the lubricant composition, thereby forming a lubricant-solvent mixture having a viscosity similar to or less than that of engine fuel. A sample of a lubricant-solvent mixture is then subjected to a constant volume combustion test to determine the reactivity associated with the lubricant-solvent mixture. The test is repeated for a range of lubricant-solvent ratios, and statistical methods are used to calculate the reactivity of the lubricant composition without solvent.

Abstract: The methods of the invention are aimed toward the determination of corrosivity, ageing, fingerprinting and contaminants, as well as the functional diagnosis, decontamination, depolarisation and detoxification of oils and technical fluids, such as mineral insulating, natural and/or synthetic esters, lubricants, hydraulic fluids, diathermic fluids and technical fluids in general, used in apparatuses and equipment, such as electric transformers, reactors, bushings, switches and turbines, for the generation, transmission, distribution and use of power.

Abstract: A method for evaluating a lubrication containment system is set forth herein. In one lubrication containment system, a seal runner can be fixed to the rotatable structure and seal against a static radial seal supported by the sump housing. The method also includes the step of rotating the structure relative to the sump housing. The method also includes the step of directing test fluid to the structure inside the sump housing. The method also includes the step of quantifying an accumulation of test lubricant at the seal runner during rotation by omitting the radial seal from the lubrication containment system. As a result, test lubricant can pass out of the sump housing. The amount of test lubricant that passes out of the sump housing, past the location where the seal runner would be or would have been, corresponds to the amount of lubricant that accumulates at the seal runner during operation in the field.

Abstract: A system for determining the type of hydraulic fluid employed in a transmission includes a translating valve, a valve position sensor, a hydraulic fluid temperature sensor, and a controller. The valve position sensor is operable to measure the actual time the valve takes to translate within the hydraulic fluid. The controller is operable to compare the actual time of valve translation to an expected time of valve translation. If the actual time of valve translation is different than the expected time of valve translation to a predetermined degree, the controller is operable to signal an operator of the motor vehicle or a service technician that the hydraulic fluid being used in the transmission is not meeting operating expectations.

Abstract: The invention relates to a device and to a method for determining the proportion of fuel in a combustion engine lubricating oil. The device according to the invention comprises a column (12) with at least 22000 theoretical plates and a steady state phase capable of separating the fuel, the oil, the internal standard contained in the oil and the solvent, in which the oil and the internal standard are diluted, and a heating module (120) capable of causing an increase in the temperature of the column (12) at a rate of at least 350° C./min. In the method according to the invention, the column (12) is subjected to determined cycles during which the pressure of the carrier gas and the temperature are varied.

Abstract: An embodiment of the present invention provides for a sensing element comprising a non-conductive housing with three chambers for detecting oil conductivity, additive depletion and oxidation, and water contamination, respectively. Through the monitoring of an array of oil sensors, an early warning of oil degradation due to oxidation is provided. The monitoring system further detects excess soot, water and other contaminants in the oil. The oil sensor array and related monitoring system decrease the likelihood of catastrophic engine failure through the early detection and warning of a decrease in oil quality thereby reducing vehicle owner outlays for servicing and disposal fees while further aiding in the satisfaction of environmental protection regulations.

Abstract: The invention relates to a test method and a test device for the determination of an oil separation tendency of lubricating greases under pressure load. In the method, a predetermined test pressure is applied to a test volume (2) filled with lubricating grease (27) over a predetermined test period (32), the lubricating grease (27) of the test volume (2) is contacted with an oil absorption or oil separation element (11), and the change of the test volume (2) is detected on the basis of an absorption or separation of oil (29) separated from the lubricating grease (27) by the oil absorption or oil separation element (11) at the end of the test period (32). To be able to estimate the oil separation tendency of lubricating grease more exactly, in the method according to the invention, the time history of the change of the test volume (2) representative of the oil separation is detected over the test period (32).

Abstract: The present disclosure relates to a lubricant composition comprising a first phosphorus compound, a second phosphorus compound, and a third phosphorus compound, wherein the first phosphorus compound is present in the lubricant composition in an amount to provide between about 120 and 350 ppm phosphorus. The lubricant composition may provide robust anti-wear and reduced pitting.

Abstract: Disclosed herein is a system and method for screening a liquid composition. The system includes (a) a test cell having a top portion and a bottom portion, the test cell comprising (i) a test panel removably mounted to the top portion of the test cell at an angle of between about 10 to about 45 degrees to the horizontal of the test cell; (ii) a reservoir for holding the liquid composition; and (iii) a means for applying a substantially uniform coating of the liquid composition from the reservoir to at least a portion of the test panel; (b) a means for heating the test panel according to a first temperature control program; (c) a means for heating the reservoir according to a second temperature control program; and (d) a means for supplying an oxidizing gas to the test cell.

Abstract: Rapid determination of low temperature residual wax contamination in basestock oil provides a basis for real time correlation of basestock quality with the low temperature viscometric properties of fully formulated oils made using said basestock oil.

Abstract: A fluid discrimination apparatus and a fluid discrimination method are provided for carrying out with accuracy a fluid discrimination such as a fluid type discrimination, a concentration discrimination, the fluid existence or nonexistence discrimination, and a fluid temperature discrimination for a discriminated fluid that is stored in a tank or the like. A characteristic measured value as an index value that indicates the characteristics of the fluid to be discriminated is measured, and a discrimination of a fluid is carried out by comparing the fluid discrimination data that indicates the relationship between a fluid that has been measured in advance and a characteristic value of the fluid with the characteristic measured value.

Abstract: A vehicle has a transmission, a transmission filter, and a controller having an algorithm or method for predicting the remaining useful life of the filter. The algorithm or method uses a sensor to detect an operating event of the transmission, such as a completed shift event or zero transmission output speed event, and increases a stored value of an accumulated distance and time variable. A shift sensor is operable for comparing a detected speed ratio of the transmission to a stored threshold speed ratio for determining the completed shift event. The remaining useful filter life is predicted using one or more look up tables using the values of the accumulated distance and time variables. The accumulated distance is calculated in part by dividing a prior recorded accumulated distance value by a ratio of an output speed of the transmission to an actual vehicle speed.

Abstract: At least one operating quantity of an internal combustion engine is recorded. A criterion is derived for an oil change from the at least one operating quantity by converting a number of operating quantities, as input quantities of a neural and/or probabilistic computer network, into a number of state quantities characterizing the oil as output quantities of the computer network, wherein at least some of the output quantities are subjected to a check, the criterion being derived from the check.

Abstract: An arrangement and method for determining a characteristic variable of a fluid having a movably suspended measuring element, a restraining element, an advancing element and a control device. The control device is designed to actuate the restraining element and/or the advancing element in order to move the measuring element between the first measuring point and the second measuring point, to determine a time period which the measuring element requires in order to be moved between the first measuring point and the second measuring point, and to determine a characteristic variable of the fluid on the basis of the determined time period, a predetermined force and a known geometry.

Abstract: A capacitive sensor in its simplest form has three identical plated spatial electrodes, which are positioned equally spaced apart, in order, alignment and parallel with each other. The first and third electrodes are the outer electrodes and connected in parallel by a first lead wire serving as a first electrical pole to be a group of the integrated electrodes. The second electrode is the middle electrode and connected by a second lead wire serving as a second electrical pole. The sensor is applied by an alternating current (AC) excitation by an AC device. The present invention method includes application of referencing and sensing capacitive sensors to obtain a measured temperature compensated electrical property of the oil to thereby obtain a measured remaining usage so as to a predicted one for the oil.

Abstract: To provide an engine oil degradation-estimating device and a device for estimating antioxidant performance of engine oil which are capable of determining degradation and an antioxidant performance of engine oil inexpensively and accurately, thereby making it possible to properly determine degradation of the engine oil and the time for replacement of the engine oil. The engine oil degradation-estimating device includes an ECU 2. The ECU 2 estimates an antioxidant performance OIT and a cleanliness preservation performance TBN of engine oil, and determines degradation of engine oil based on the estimated antioxidant performance OIT and cleanliness preservation performance TBN. The device for estimating antioxidant performance of engine oil also includes an ECU 2. The ECU 2 acquires concentration [FUEL] of fuel in engine oil, and estimates the antioxidant performance of the engine oil based on the acquired fuel concentration [FUEL].