JPS60145412A - Engine oil maintenance system - Google Patents

Abstract

PURPOSE:To objectively grasp deterioration of engine oil and its replacing timing by providing an engine oil deterioration judging device to judge the deterioration of engine oil, and a computer to output the compounding ratio of the additives to the oil. CONSTITUTION:An engine oil deterioration judging device 2 analyzes the concentration of special gases in the blow-bye gas exhausted from a vehicle 1 under maintenance to measure deterioration of the engine oil. A computer 4 selects the additives to the engine oil of the vehicle 1 under maintenance and outputs the composition of the additives. A compounding device 5 compounds the oil- additivies from a plurality of additive-tanks 52. An oil-additive mixer 6 mixes the additives thus compounded and checks the quality of the mixture. By this method the deterioration of the engine oil and its replacing timing are objectively grasped, and secure control of the engine oil can be made.

Description

[Detailed Description of the Invention] The present invention measures and determines the deterioration of engine oil, removes oil that has deteriorated beyond a certain level from the vehicle, and uses a computer to determine the additives and blending ratio that should be added to the oil. This invention relates to an engine oil maintenance system in which selected additives are added to degraded oil in formulations 1 to 1, and the prepared oil is supplied to a vehicle.

Engine oil is supplied to the kinetic friction parts of the engine,
It performs various functions such as lubrication, cooling, and sealing under high temperatures, making the engine run smoothly and promoting long-term use, so inspection is essential in vehicle maintenance, especially to check for engine oil deterioration and replacement. Management of timing, etc. is essential.

Conventionally, this kind of engine oil management has been done by visually observing the color of the oil adhering to the oil level gauge or the oil drawn out to the oil change machine, or by checking whether the engine is in a restless state during idling, deterioration of fuel efficiency, or Depending on the occurrence of abnormal noises when starting or operating the engine, or abnormally high-pitched operating noises at such times, it is necessary to determine whether the engine oil has deteriorated and replace the deteriorated oil after a certain period of time or after a certain period of driving. This was done by changing the oil based on the distance traveled.

However, although the method of determining oil deterioration based on the color of the oil is simple, it is difficult to ensure objectivity and requires skill, and judgment based on engine operating conditions is arbitrary. Oil deterioration cannot be promptly dealt with by periodic or mileage-based management. As described above, with conventional methods, it is extremely difficult to objectively grasp the deterioration of oil and correctly judge when it is time to replace the oil, which poses an obstacle to oil maintenance and inspection. Moreover, when changing the oil, specified engine oil is used based on the car model and engine model, and the properties of the oil are uniformly determined by the oil and additives added to the oil. There is no option to choose an engine oil with oil additives added depending on the individual vehicle, and there is no equipment to objectively judge the suitability of engine oil, so drivers are generally forced to use unsuitable oil. There were quite a few. This tendency is particularly noticeable in vehicles with established driving conditions, applications, and engine usage conditions, causing engine malfunctions and exhaust gas pollution.

Therefore, the inventor decided to develop and completed an engine oil deterioration determination device that can objectively grasp the deterioration of engine oil and accurately manage the timing of oil replacement based on this. That is, this determination device detects blow-by gas (blow-b)' out of the gases exhausted during vehicle operation.
It was developed with a focus on gas) K, and by analyzing the concentration of specific gases contained in this blow-by gas,
We focused on the ability to determine the degree of deterioration of engine oil.

In other words, blow-by gas is mainly caused by the air-fuel mixture being forced into the groove of the piston ring during the compression stroke and being pushed out unburned into the crankcase by the pressure of the combustion gas, and this gas contains a large amount of HC ( known to contain hydrocarbons). Normally, the sliding surfaces of the piston and cylinder are sealed by an oil film of engine oil, so the amount of blow-by gas discharged or the HC concentration in the blow-by gas maintains an approximately constant relationship. When engine oil deteriorates and its lubricity decreases, the formation of an oil film slows down, the sealing effect between the piston and cylinder decreases, and blow-by gas is pushed out to the crankcase. In other words, as the engine oil deteriorates, the HC concentration in the blow-by gas increases.
By measuring the concentration, the degree of deterioration of the engine oil can be determined.

The present invention objectively determines the deterioration of engine oil based on the above principle, and for engine oils that have deteriorated beyond a certain level, information specific to the vehicle being serviced is input into a computer, and the optimal oil additive is selected. Additives prepared based on the blending ratio are added to deteriorated oil to improve the quality of the oil and reduce its deterioration, and this prepared oil is used to refuel vehicles. It is possible to objectively judge the deterioration of engine oil and accurately manage the oil replacement period, and for oils that require maintenance if the deterioration is moderate or higher, oil additives that match the characteristics of the vehicle are added to reduce deterioration. In addition to promoting the effective use of resources by promoting the long-term use of oil, we aim to improve engine performance, fuel efficiency, and exhaust gas pollution, and we also provide a series of steps from determining engine oil deterioration to dealing with each determined oil. The objective is to provide an engine oil maintenance system that systematizes the process and ensures high reliability in engine oil maintenance and inspection.

Therefore, the engine oil maintenance system of the present invention
The deterioration of the engine oil in the vehicle being serviced is determined by an engine oil deterioration determination device that analyzes the HCa level in the blow-by gas. If the deterioration of the oil is moderate or higher, the engine oil is taken out of the vehicle and mixed. Data on the physical and chemical alteration of various oil additives stored in the tank, as well as data on the physical and chemical alterations of various oil additives depending on vehicle engine conditions, driving conditions, etc., as well as analytical data on engine oil functions by adding one or more oil additives, and the addition of various oils at that time. Information specific to the maintenance vehicle is input into a computer that stores information such as the contribution rate of additives, and the oil additives to be added to the engine oil of the maintenance vehicle and their blending ratio are output, and based on this output, the specified oil The system is characterized by blending additives, mixing the blended oil additives with engine oil in a mixing tank, supplying the prepared engine oil to maintenance vehicles, and further analyzing the HC concentration in the blow-by gas. An engine oil deterioration determination device that determines the deterioration of engine oil based on physical and chemical change data of various oil additives depending on the vehicle engine condition, driving condition, etc., and engine oil function by adding one or more oil additives. By storing analysis data and information such as the contribution rate of various oil additives at that time, and inputting information unique to the vehicle being serviced, outputs the oil additives that should be added to the engine oil of the vehicle being serviced and their blending ratio. A mixing tank for storing engine oil taken out from a maintenance vehicle, and an additive blending device capable of blending a certain amount of oil additives from a plurality of additive tanks containing oil additives. It is a feature.

Hereinafter, an illustrated embodiment in which the present invention is applied to an automobile mainly equipped with a four-cycle engine that uses gasoline or liquefied petroleum gas as fuel will be described. FIG. 1 shows an outline of the maintenance system of the present invention, and this system By analyzing the concentration of a specific gas in the blow-by gas discharged from 1,
An engine oil deterioration determination device 2 that counts and quantitatively measures the deterioration of engine oil; an oil cleaning device 3 that cleans oil requiring maintenance derived from the maintenance vehicle 1 based on the determination of the determination device 2; Information on the physical and chemical changes and effects of various oil additives on various engine, driving, and road conditions, as well as the contribution of various oil additives to mitigating and reducing oil deterioration. information and information for selecting oil additives and calculating their blending ratio based on these information are stored, and by inputting information specific to the maintenance vehicle 1 to this information, A computer 4 that selects oil additives to be used and outputs and displays their blending ratio; an additive blending device 5 that blends various oil additives based on the output display of the computer 4; The oil additive mixing device 6 is configured to mix the oil additives and check the quality of the oil additives.

The engine oil deterioration determination device 2 is constructed as shown in FIGS. 2 to 4, in which 7 is a crankcase, 8 is a cylinder provided inside the crankcase 7,
9 is a piston, 10 is a connecting rod, 11 is a crank, 12 is a crankshaft, 13 is a valve, 14 is a crankcase 7
This is an oil pan installed at the bottom of the engine, and engine oil 15 is stored inside. Reference numeral 16 denotes a head cover, on the top of which an oil filler port 17 for engine oil 15 is provided. A hose 18 is made of a heat-resistant material such as Teflon, and an adapter 19 that can be attached to the fuel filler port 17 is attached to one end of the hose, and the other end is connected to the gas concentration analyzer.

The gas concentration analyzer side is an instrument that can measure the concentration of a specific gas, such as HC (hydrocarbon), in the blow-by gas led out to the hose 18, and its measurement methods include mass spectrometry, infrared analysis (dispersive type), etc. , non-dispersive type), flame ionization, gas chromatography, combustion methods, etc., but in this example, flame ionization detection as an HC detector that makes full use of the flame ionization method that responds quickly over a wide range of HC concentrations. A container 21 is used. As shown in the principle diagram shown in FIG. 4, this hydrogen flame ionization detector 21 has a counter electrode n to which an applied voltage n is applied,
A collector electrode is arranged opposite to the counter electrode, and a nozzle 5 is arranged between these electrodes, and a constant flow rate is supplied from one side of the three-way pipe to which the nozzle 5 is connected. A sample gas containing HC, that is, blow-by gas (B), which is controlled to The combustion is carried out via auxiliary combustion air (5). In the figure, the path is a hydrogen flame, the grave is a conductor whose one end is connected to the collector electrode U, and (9) is a current amplifier with high input impedance to amplify the output of the hydrogen flame ionization detector 21. After sufficient amplification, the Total 3
1, and 32 is a load resistor connected in parallel between the amplifiers.

In addition, on the gas concentration analyzer side, as shown in FIG. 3, there is a strainer 33 between the hose 18 connected to the adapter 19 and the hydrogen flame ionization detector 21, and a device that controls the flow rate of the blow-by gas to a constant value. A control valve (path shown) is inserted. 34 is a pump, 35 is a determiner consisting of an amplifier such as an operational amplifier connected to the output side between the amplifiers, and the input side thereof is a deterioration detector calibrated to the permissible limit of the HC concentration in the blow-by gas according to the measurement conditions. For the standard value of the replacement area where the deterioration is severe and the area that requires maintenance which is lower than this standard value and the deterioration is moderate or higher, the median value of that area is input as the standard value, and these inputs and amplifiers (resources) are input. ) is compared with the output, and an indicator lamp 36 connected to the output side.
, 37 and 38 are turned on to visually display the HC concentration in the blow-by gas.

Therefore, the deterioration of the engine oil can be easily determined by the illumination of the indicator lamps 3F+, 37, :ts, and whether or not it has deteriorated more than a certain standard, while the degree of deterioration can be grasped numerically by the indicator 31. It becomes possible.

In this case, among the standard values for HC concentration, the standard values for the exchange range are the normal HC concentration contained in the blow-by gas discharged after a new oil change, and the normal HC concentration contained in the blow-by gas discharged due to the deterioration of the sealing function of the oil. Considering the HC concentration contained in the blow-by gas, the HC concentration in the total blow-by gas is set to the maximum allowable limit that can function as engine oil. Therefore, each of the above reference values depends on the vehicle type, especially the engine displacement, and the driving condition of the vehicle, such as idle link, acceleration, constant speed, etc.
Since it differs depending on the deceleration state, it is desirable to make these reference values adjustable according to these conditions.
In addition, the indicator 31 is one that can respond to a wide range of HC concentrations, and the display also shows, depending on the degree of oil deterioration, for example, a pass range, a maintenance required range, a replacement range, or an approximate oil replacement time. It is desirable to calibrate.

In the actual measurement of HC concentration, accurate results can be obtained by driving the vehicle in each of the above-mentioned states, but in order to simplify and speed up maintenance inspections, it is possible to obtain accurate results by driving the vehicle in each of the above-mentioned operating states. You may choose to do so. In addition, the determiner 35
In addition to using an operational amplifier as a comparator as mentioned above,
It is also possible to construct it using a known discrimination circuit or bridge circuit that makes full use of transistors and diodes.

The oil cleaning device 3 is equipped with a supply/discharge vibrator 39 connected to one end with a supply/discharge nozzle N that can be inserted into the oil recovery hole (path shown in the figure) of the oil pan 14. Valves 40, 41.

A bypass pipe 43 is connected to the control valves 40 and 41, and a connecting pipe 44 is connected to the control valve 42, and the flow of engine oil to be supplied and discharged is controlled by mechanical or electromagnetic force. The route can be changed. 45, 4
Reference numeral 6 indicates a filter disposed in the supply/discharge vibrator 39 between the direction control valve 4 (1 and 41), and is composed of, for example, a magnetic filter and a laminated filter, and 47 indicates the direction control valve 4-1.
A supply/discharge pump installed in the supply/discharge pipe 39 between , 42 and 4
8 is a waste oil tank.

The computer 4 stores various types of information 49 regarding the vehicle and oil additives, and this information 49 includes, for example, the engine type of the vehicle, the purpose of the vehicle, the period of use, and other conditions regarding the engine, as well as the conditions for continuous long-distance driving. various driving conditions, such as whether there is a lot of starting and stopping; road conditions, such as whether the vehicle is often driven on roads with a lot of sand or dust; and whether there is a lot of hill driving. Includes empirical rules and experimental data on the extent to which oil additives physically and chemically alter and influence oil additives. For example, oil additives usually include detergent dispersants, antioxidants, corrosion inhibitors, antifoaming agents, viscosity index improvers, pour point depressants, etc., but the physical properties of these additives vary depending on the above conditions. This information relates to whether chemical deterioration occurs or not, and information numerically expressing physicochemical deterioration when the above conditions are combined.

In addition, the information 49 includes information regarding effective oil additives and the blending ratio of the oil additives based on the degree of contribution to recovery, in order to restore the functions of the physicochemically degraded engine oil.

The information is information unique to each maintenance vehicle that is input into the computer 4, such as the type and model of the maintenance vehicle 1, the engine oil used, the engine type, the purpose of the vehicle, the period of use, the aforementioned driving conditions, and the road surface on which it was driven. This includes the status of And these information 49. t), the computer 4 performs control calculations, selects the oil additives to be used, and displays their blending ratios on the output 51.

The additive blending device 5 includes, for example, a plurality of types of additive tanks 52 containing the oil additives therein, and a blender 53 such as a measuring cylinder having a scale display for blending these additives. A supply pipe 54 is installed between these additive tanks 52 and the corresponding compounders 53, and a pressure pipe 56 communicating with a pressure bomb 55 is provided in each tank 52.
is piped to send pressurized air into each tank 52,
The oil additive contained inside can be pumped.

57 is a blended pulp, 58 and 59 are open/close pulps, and 6o is a conduit whose upper end is connected to the sub-tank 61, and whose lower end is piped toward the blending tank 62. In this case, the engine oil that is in use is often less than the specified amount, so in order to supplement this, an oil tank containing base oil is installed in parallel so that a certain amount can be replenished. This is desirable.

The oil additive mixing device 6 has the above-mentioned blending tank 62 that can contain oil that requires maintenance, and within this blending tank 62 there is a stirrer 63 and a known PH measurement sensor 64 that measures the residual alkalinity of the oil. It is provided. 65 is a PH indicator, and 66 is an amplifier connected between the indicator 65 and the sensor 64.

When inspecting and servicing engine oil using the maintenance system configured in this way, attach the adapter 19 to the fuel filler port 17 of the maintenance vehicle 1, set the gas concentration analyzer side to the operating state, and then 1 to the desired state. When the engine starts, the air-fuel mixture that was pushed into the groove of the piston ring during the compression stroke of the piston 9 is pushed out unburned into the crankcase 7 by the pressure of the combustion gas, producing blow-by gas. This flows toward the upper part of the crankcase 7 as shown by the arrow in FIG. 2, is guided through the fuel filler port 17 and the hose 18, and is introduced into the gas concentration analyzer side. The blow-by gas led to the above analyzer passes through a strainer to remove dust and dirt from the gas, and then the flow rate is adjusted to a constant level by the control valve (the channel shown in the figure). is mixed with the hydrogen gas supplied from the other side in the three-way pipe section to the nozzle 5.
The mixture is blown out and combusted between the counter electrode z3 and the collector electrode array via the auxiliary combustion air supplied from the air conduit 27.

Combustion of the blow-by gas, more specifically, combustion of HC in the blow-by gas, generates complex ions, and an electric field applied across the hydrogen flame path causes an ionic current to flow between the collector electrode array and the counter electrode. The magnitude of this ion current is a function of the number of carbon atoms passing through the flame, exhibits a response proportional to the characteristics and flow rate of the blow-by gas, and has linearity. That is, the ionic current is proportional to the detected HC concentration. Since this ion current is very weak, it is amplified by a high input impedance amplifier (9) and guided to an indicator 31, which responds in proportion to the HC concentration in the blow-by gas. Therefore, the engine oil deteriorates and the piston 9 and cylinder 8
If the formation of an oil film between the oil film and the sealing effect decreases, the amount of blow-by gas will increase approximately in proportion to the degree of deterioration. Since the HC concentration in the engine oil is increased, the deterioration of the engine oil can be numerically grasped by the response of the indicator 31.

At this time, if the response of the indicator 31 is calibrated in advance based on the correlation between the displacement of the maintenance vehicle 1 and the driving condition of the vehicle at the time of measurement before measuring the HC concentration, it will be compatible with all vehicles and measurement conditions. In addition, instead of or in addition to the indicator scale, the display section of the indicator 31 may be marked with, for example, "pass range,""maintenancearea,""replacementarea," or [
If you mark the oil replacement time as ``Replacement Required After O Months - 1'', you can predict the degree of oil deterioration and the oil replacement time.

On the other hand, the amplified ion current is input to the determiner 35,
Before and after this, when the reference values converted according to the measurement conditions described above are adjusted and input to the judge 35, the magnitude relationship between each reference value and the ion current is judged, and the ON-OF
One of the display lamps 36, 37, and 38 is lit by the F output. For example, these lamps%, 37, 3
If 8 is configured in a circuit so that it lights up in the pass range, maintenance required range, and replacement range, when the HC concentration in the blow-by gas is lower than the standard value of the maintenance required range, in other words, engine oil deterioration will be prevented. When the condition is minor, the indicator lamp 36 lights up to notify that it can be used continuously, and when the HC concentration is above the standard value for the maintenance area and below the standard value for the replacement area, that is, the engine oil has deteriorated. When the condition is moderate to severe, the indicator lamp 37 lights up to notify that oil maintenance is required, and when the HC concentration exceeds the standard value for the replacement range, that is, when the oil has deteriorated beyond the allowable limit. The oil indicator lamp lights up to notify you that oil cannot be used.

Therefore, depending on whether or not these indicator lamps 36 , 37 , and 38 are lit, it is possible to quickly know whether the engine oil function is working or not or how the oil has deteriorated. Since it can be confirmed by counting or quantitatively, it is possible to give objectivity to the judgment.

In this way, the engine oil deterioration determination device 2
Oils that are determined to be "acceptable oils" are confirmed to have no problems when used as they are, and oils that are determined to be "required oils" are stopped from operating the maintenance vehicle 1.
Insert the supply/discharge nozzle N into the oil recovery hole of the oil pan 14, switch the directional control valves 40, 41, and 42, drive the supply/discharge pump 47, and carry out the engine oil 15 in the oil pan 14. , connect this to the supply/discharge pipe 39
From there, the oil is guided again to the supply/discharge vibrator 39 via the bypass pipe 43 and stored in the waste oil tank 48, while new oil is supplied from the oil filler port 17 for oil exchange.

In addition, the oil determined to be "maintenance oil" is collected by the directional control valve 40, when the operation of the maintenance vehicle 1 is stopped and the supply/discharge nozzle N is inserted into the oil recovery hole of the oil pan 14.
41 and 42, drive the supply/discharge pump 47 to carry out the engine oil 15 in the oil pan 14, guide it from the supply/discharge vibrator 39 to the connecting pipe 44, and transfer it to the mixing tank 62.
to be accommodated. During this suction and conveyance, engine oil 15
passes through filters 45 and 46 inserted in the flow path,
Magnetic solids such as metal powder and dirt mixed in the oil are removed. In this way, the engine oil 15 accommodated in the blending tank 62 is immediately stirred by the stirrer 63, and the PH sensor 64 measures the degree of alkali remaining in the oil to confirm the degree of deterioration.

On the other hand, for the maintenance vehicle 1 that has been determined by the oil deterioration determination device 2 to require “maintenance oil”, the maintenance vehicle 1
Unique information (1) is created by listening to the serviceman or by expanding the driver's card. This information includes, for example, the 10 types of vehicles being serviced, model, engine type, engine oil used, purpose, period of use, car manufacturer, engine displacement, long distance, high speed, whether or not the vehicle is operated continuously, whether or not the vehicle is operated with many starts and stops, and the driving direction. Whether the road was sandy or dusty, how often low gears are used on slopes, etc., and this information 50 is sent to the computer 4 or CP installed in the maintenance shop.
Enter it into the terminal installed at the maintenance shop that is online with U.

The computer 4 calculates the correlation between the input information, the vehicle engine type, driving conditions, road conditions, and oil additives, the physicochemical data of each oil additive, and the function of the oil in each condition. Based on the four pieces of already stored information regarding the oil additives to be used for recovery and the blending ratio when these are used in combination, these are compared, controlled, and calculated to determine the engine oil to be used for the maintenance vehicle 1. Outputs the oil additives to be added to the oil additives and their mixing ratios51
to display this. In this case, if information such as the measured pH of the oil and the condition of the oil, such as the degree of foaming, is added to the information, a more optimal oil additive can be created.

Next, the serviceman drives the pressure pump 55 of the additive blending device 5 based on the output 51 of the computer 4, and pumps the pressurized air into the additive tank containing the corresponding oil additive.
Send it to 2. After that, a predetermined mixing valve 57 is opened, the oil additive is dripped into the mixer 53, and the amount of the oil additive is mixed based on the mixing amount. After that, the opening/closing valve 59 is opened and the mixing tank 6 is filled.
Let it flow down into 2. In this case, if a tank containing a base oil of specified or unspecified engine oil is installed so that it can be supplied together with each additive into the mixing tank 62, the shortage of engine oil can be replenished. In this way, the alkalinity of 15 volumes of engine oil with predetermined oil additives added is measured again by the PH sensor 64, and when the oil quality is confirmed and improvement in deterioration is confirmed,
The supply/discharge pump 47 is started to carry the engine oil in the mixing tank 62 into the maintenance vehicle 1 via the supply/discharge pipe 39.

Thereafter, the maintenance vehicle 1 is set to a predetermined operating state again, and the oil deterioration determining device 2 measures the deterioration to confirm improvement of the deterioration. In this way, in this maintenance system, improvement in deterioration of the engine oil after preparation is strictly confirmed by checking the alkalinity with the PH sensor 64 and checking with the oil deterioration determination device 2.
Misidentification can be prevented, oil quality can be strictly controlled, and high reliability can be ensured for oil quality and maintenance systems.

In the above-mentioned embodiment, the HC concentration in the blow-by gas is measured by the flame ionization method, but it may also be measured by other methods such as infrared analysis, or even by CVS instead of the concentration method.
It may be measured by a gravimetric method such as the total bag method or the total bag method.Also, in this example, the case where it is applied to a car equipped with a 4-stroke engine is explained, but it is also possible to measure by a weight method such as a total bag method. It can also be applied to automobiles and motorcycles; in this case, since vehicles equipped with two-stroke engines generally emit a large amount of HC,
It is necessary to use an analyzer that responds to a wide range of concentrations or weights.The engine oil maintenance system of the present invention has been made possible to objectively confirm oil deterioration using the engine oil deterioration determination device as described above. It is possible to objectively grasp and accurately manage the deterioration of the engine oil function and the timing of replacement, thereby having the effect of improving engine malfunction and exhaust gas pollution caused by the use of deteriorated oil. In addition, in the present invention, for oils with moderate or higher deterioration, the optimal oil additive that matches the vehicle being serviced is selected17, reducing deterioration of engine oil, improving quality, and ensuring long-term use. By doing so, it is possible to maintain high engine performance and to make effective use of the sound source.

Moreover, in the present invention, as an engine oil maintenance method,
We have systematized each process, including oil deterioration determination, oil treatment based on the determination results, and the selection and addition of the optimal oil additive to improve the functionality of oil that has deteriorated moderately or more. This method has the advantage of ensuring high reliability compared to seed work.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and FIGS. 2 to 4 are principle diagrams showing an example of an engine oil deterioration determination device used in the present invention, and explanatory diagrams showing the main parts thereof. . DESCRIPTION OF SYMBOLS 1... Maintenance vehicle, 2... Engine oil deterioration determination device, 4... Computer, 5... Additive tank ft
, 15...engine oil, 49,5o...information,
51...Output, 52...Additive tank, 62...
Mixing tank JP-A Sho GO-145412 (9)

Claims (2)

[Claims] (1) The deterioration of the engine oil in the maintenance vehicle is determined by an engine oil deterioration determination device that analyzes the HC concentration in the blow-by gas, and if the oil deterioration is moderate or higher, the engine oil is removed from the maintenance vehicle. At the same time, data on physical and chemical alterations of various oil additives depending on vehicle engine conditions, driving conditions, etc., analysis data on engine oil function due to the addition of one or more oil additives, and data on that occasion are also collected. Information specific to the vehicle being serviced is input into a computer that stores information such as the contribution rate of various oil additives, and the oil additives that should be added to the engine oil of the vehicle being serviced and their blending ratios are output, and based on this output. An engine oil maintenance system characterized in that a predetermined oil additive is blended, the blended oil additive is mixed with engine oil in a mixing tank, and the prepared engine oil is supplied to a maintenance vehicle. (2) An engine oil deterioration determination device that analyzes the HC concentration in blow-by gas to determine engine oil deterioration, and data on physical and chemical alterations of various oil additives depending on vehicle engine conditions, driving conditions, etc. Alternatively, by storing analysis data of engine oil function by adding multiple oil additives and information such as the contribution rate of various oil additives at that time, and inputting information specific to the vehicle being serviced, the engine oil of the vehicle being serviced can be A computer that outputs the oil additives to be added and their mixing ratios, a mixing tank that stores the engine oil taken out from the maintenance vehicle, and multiple additive tanks that store oil additives to mix a certain amount of oil additives. An engine oil maintenance system characterized by being equipped with a capable additive mixing device.