DE102013224963B4 - Method and device for plausibilizing information about a change of a lubricant in an internal combustion engine - Google Patents

Abstract

Method for plausibilizing information about a change of a lubricant (16) in an internal combustion engine, the internal combustion engine comprising: - a crankcase (15), from which a vent line (24) leads into an intake tract (20) of the internal combustion engine, so that at certain Operating conditions of the internal combustion engine in the crankcase (15) existing fuel vapor in the intake tract (20) can be initiated - an electronic control device (40) for controlling and regulating the internal combustion engine with a lambda controller (44) and an oil dilution model (OIL_M) the fuel input and fuel discharge modeled into the lubricant (16), wherein - the control device (40) information (LV_OIL_CHG) is supplied via a supposedly occurred change of the lubricant (16), - If fulfillment of predetermined release conditions for the plausibility check in a subsequent idling phase (LL2) of the Brennkraf machine (λ_CONT) a lambda probe (57) is monitored, and - if the signal (λ_CONT) falls below a predetermined threshold (λ_THD), the information (LV_OIL_CHG) on the change of the lubricant (16) is not confirmed, otherwise the information (LV_OIL_CHG) is confirmed.

Description

The present invention relates to a method and a device for plausibilizing information about a change of a lubricant in an internal combustion engine.

Modern internal combustion engines, in particular Otto internal combustion engines with direct fuel injection show an increased fuel input into the engine oil, which is located as a lubricant in the crankcase. Especially immediately after a cold start of an internal combustion engine unburned fuel can be dissolved in the engine oil of the internal combustion engine, which then evaporates again with increasing operating temperature. In reciprocating internal combustion engines according to the Otto principle or according to the diesel principle fuel can condense on the cold wall of the combustion chamber, especially in the first seconds after a cold start on the oil film and dissolve in the oil film.

This oil dilution by the fuel causes an undesirable change in the lubricating properties of the engine oil. Thereby, the wear and the probability of the occurrence of a defect can be increased and the life expectancy of the internal combustion engine can be reduced.

The dissolved fuel in the engine oil evaporates again with increasing operating temperature and accumulates in a reciprocating internal combustion engine, especially in the crankcase. To prevent the emission of unburned fuel into the environment, the crankcase is connected to the intake manifold via a crankcase breather. Due to a pressure gradient from the crankcase to the intake tract, a dependent on the operating condition of the internal combustion engine mass flow of exhaust gas, air and possibly fuel, which evaporates in the crankcase from the engine oil.

The control device of a modern internal combustion engine, generally referred to as engine control, monitors the functionality of its components by means of a diagnosis of the operating parameters available to it. Fuel that evaporates from the engine oil and enters the intake manifold via the crankcase breather must be taken into account in the injection control. For this reason, attempts are made to determine the currently registered fuel quantity in the engine oil as accurately as possible in order to be able to take appropriate measures if necessary.

In the DE 10 2010 043 780 A1 A method for determining the amount of fuel outgassing from a lubricant, which is located in a housing of an internal combustion engine, is described in an intake tract of the internal combustion engine.

The method comprises (a) setting a first purge flow through the housing, (b) measuring a first output value of a lambda governor of the internal combustion engine, (c) setting a second purge flow through the housing, wherein the second purge flow is a different one compared to the first purge flow Flow strength, (d) measuring a second output value of the internal combustion engine lambda controller, and (e) determining the amount of fuel outgassing based on the measured first output value and the measured second output value.

The DE 10 2006 059 674 A1 shows a method and apparatus for detecting a continuous fuel input in the lubricating oil of an internal combustion engine, in particular an internal combustion engine for driving a motor vehicle. The continuous fuel input is determined based on hydrocarbons which outgas from the lubricating oil and enter the combustion process via a crankcase ventilation provided in the internal combustion engine. Preferably, the continuous fuel input occurring during operation of the internal combustion engine, in particular during an inspection of the internal combustion engine as a result of additional outgassing, is calculated from the difference with values measured at the factory on an application engine.

The DE 10 2007 046 489 B3 shows a method for operating an internal combustion engine with a vent of a crankcase in an intake tract of the internal combustion engine with the following steps: (a) detecting operating parameters of the internal combustion engine, (b) determining a mass flow of fuel from the crankcase into the intake tract in dependence on the detected operating parameters , (c) controlling or monitoring the internal combustion engine as a function of the fuel mass flow from the crankcase into the intake tract.

The quality of the engine oil is not only affected by the dilution with fuel by the blow-by effects mentioned, but it must also be considered a certain amount of wear, among other things by thermal stress, by penetration of combustion residues and absorption of particles due to abrasion is justified. With this wear u. a. the viscosity and lubrication properties of the engine oil, requiring replacement at certain intervals.

A method for determining the timing for the lubricating oil change in motor vehicles are well known. For example, in the EP 08 66 428 A2 described that the effectiveness of the lubricating oil is detected by continuously detecting the dielectric constant, the viscosity and the electrical conductivity of the lubricant oil in the lubricating oil circuit of the internal combustion engine and these parameters are constantly compared with the values determined in the vehicle, the dielectric constant, the viscosity and the electrical conductivity and that, given a predetermined deviation of these parameters from the parameters determined in the vehicle test, an indication for an imminent oil change takes place.

After the oil change, whether in the context of an inspection of the motor vehicle in a workshop or by the driver of the motor vehicle itself, no or no significant proportion of fuel in the engine oil longer exists and the determined before the oil change amount of fuel in the engine oil must be adjusted accordingly, d. H. be set to the value zero or to a value corresponding to the remaining engine oil in percentage.

The information about a completed oil change can be entered both in the workshop via a diagnostic computer or by means of a workshop tester or else via the instrument cluster of the motor vehicle by the driver himself. This information is forwarded to the engine control unit and the control strategy of the internal combustion engine adapted accordingly, in particular also set the time interval or kilometer interval for the next oil change date.

Since resetting the value for the oil dilution has a considerable influence on the system behavior (for example, if no emergency operation is initiated despite high oil dilution, which increases the risk of engine observers or if diagnostic routines are released, which then lead to incorrect results), the Information that an oil change has taken place. This is also referred to below as plausibility of the oil change information.

The invention has for its object to provide a method and an apparatus with which or with the information in a simple manner about a change of a lubricant in an internal combustion engine can be plausible.

This object is solved by the subject matters of the independent claims. Preferred developments are defined in the dependent claims.

The invention is characterized by a method and a corresponding device for plausibilizing information about a change of a lubricant in an internal combustion engine. The internal combustion engine has a crankcase, from which a vent line leads into an intake tract of the internal combustion engine, so that in certain operating conditions of the internal combustion engine in the crankcase existing fuel vapor can be introduced into the intake tract. An electronic control device is provided for controlling and regulating the internal combustion engine with a lambda controller and an oil dilution model, which models the fuel input and fuel discharge into the lubricant. The control device is supplied with information about a supposedly occurring change of the lubricant and upon fulfillment of predetermined release conditions for the plausibility check, the signal of the lambda probe is monitored in a subsequent idling phase of the internal combustion engine. If the signal falls below a predetermined threshold, the information about the change of the lubricant is not confirmed, otherwise the information is confirmed.

The invention is based on the recognition that, in the case of an actual change of the lubricant, for example of the engine oil, ideally no fuel, practically no more fuel is present in the fresh lubricant. Accordingly, the signal of a lambda probe would have to show no great deviation in the direction of rich mixture in an idling phase of the internal combustion engine following input of the information that a change of the lubricant has taken place. If this is the case, the information about the change of the lubricant is confirmed.

However, if the signal of the lambda probe deviates during this observation period idle phase by more than a predetermined value, this is an indication that there is still a large amount of outgassing fuel in the lubricant, so no change of lubricant may have occurred. In this way, incorrect inputs made by the driver of the vehicle can be detected via a supposedly carried out change of the lubricant in the instrument cluster.

This can be safely prevented consequential damage to the internal combustion engine, which could arise due to incorrect input.

According to advantageous embodiments of the invention, the plausibility check is only performed when the temperature of the lubricant has exceeded a predetermined threshold and / or the oil dilution model indicates that the proportion of fuel in the lubricant has exceeded a predetermined threshold. This ensures that the signal of the lambda probe and the actual load of the lubricant with fuel and this leads to a meaningful result.

According to one embodiment of the invention, confirmed parameter information about a change of the lubricant model parameters of the oil dilution model regarding the entry and discharge of fuel in the lubricant. As a result, the state of the lubricant with respect to contained fuel is known, this contributes to a very precise control and control of the internal combustion engine.

Since a small residual amount of used lubricant always remains in the internal combustion engine when changing the lubricant, it is advantageous to set the threshold value for the lambda probe signal at which the decision is made as to whether a lubricant change has taken place or not. that the information about the change of the lubricant is only confirmed if the signal of the lambda probe by less than z. B. 15-20% deviates from a neutral value.

An embodiment of the present invention will be explained in more detail with reference to the accompanying figures. Show it:

1 a schematic representation of an internal combustion engine with associated control device,

2 a flowchart of a program for plausibility of the oil change information and

3 Diagrams of different time profiles for illustrating the method according to the invention during operation of the internal combustion engine.

1 shows a schematic representation of an internal combustion engine 10 with a combustion chamber 11 in a cylinder 12 , The combustion chamber 11 is on one side (in 1 on its underside) from a piston 13 completed. The piston 13 is over a connecting rod 14 with an in 1 not shown crankshaft in a crankcase 15 connected. The internal combustion engine 10 , especially in the cylinder 12 moving pistons 13 is from a lubricant 16 lubricated, located in the crankcase 15 collects and from in 1 circulated and filtered facilities not shown.

The internal combustion engine 10 also has an intake tract 20 on, in the flow direction of the sucked air in succession, an air filter 21 , a throttle 22 and an air mass sensor serving as a load sensor 23 are arranged. As a load sensor may alternatively or additionally an intake manifold pressure sensor in the intake 20 be provided. It also flows into the intake system 20 downstream of the throttle 22 a vent line 24 of the crankcase 15 , In the vent line 24 a shut-off valve, in particular an electric shut-off valve may be provided (not shown).

The intake tract 20 is via a gas inlet valve 25 with the combustion chamber 11 connected. The gas inlet valve 25 is by means of a camshaft 26 controlled. At the head of the cylinder 12 the internal combustion engine 10 are also a fuel injection valve 27 for direct injection of the fuel into the combustion chamber 11 and a spark plug 28 arranged. The fuel injector 27 can alternatively at the intake 20 and thus in the flow direction in front of the inlet valve 25 be arranged. In the case of a diesel engine, the spark plug 28 omitted.

The combustion chamber 11 the internal combustion engine 10 also has a gas outlet valve 29 that by means of a camshaft 30 is controlled, with an exhaust tract 31 in connection. In the exhaust tract 31 can one or more catalytic converters 32 and / or other means for filtering or conditioning exhaust gases of the internal combustion engine 10 be arranged.

For controlling and / or regulating the internal combustion engine 10 is an electronic control unit (ECU) 40 intended. The control device 40 contains a computing unit (processor) 41 that with a program memory 42 and a value memory 43 (Data memory) is coupled. The arithmetic unit 40 , the program memory 42 and the value memory 43 may each comprise one or more microelectronic components. Alternatively, these components may be partially or fully integrated in a single microelectronic device. In the program memory 42 or the value memory 43 programs or values are stored, which are for the operation of the internal combustion engine 10 are necessary. In particular, in the program memory 42 implements a method for checking the plausibility of the information on an oil change that has taken place during certain operating ranges of the internal combustion engine 10 from the arithmetic unit 41 is processed, as it is based on the 2 will be explained in more detail. Also, in the program memory 42 implemented a so-called oil dilution model OIL_M, with which the fuel input into the lubricant 16 and the fuel discharge from the lubricant 16 is determined. Such an oil dilution model OIL_M is for example in the DE 10 2010 006 580 B3 described, the contents of which are hereby incorporated.

In the value memory 43 Among other things, thresholds T_OIL_THD, λ_THD are stored, the meanings of which are also based on the description of the 2 will be explained in more detail.

In addition, in the control device 40 a lambda controller 44 implemented known mode of operation, with the help of the air-fuel ratio in the combustion chamber 11 set to a setpoint, usually lambda = 1, so that in the catalytic converter 32 an optimal conversion rate is achieved.

The control device 40 Several sensors are assigned, which record different measured variables and in each case determine the measured value of the measured variable. Operating variables include not only the measured quantities but also variables derived therefrom. The control device 40 determined depending on at least one of the measured variables and / or the operating variables manipulated variables, which are then converted into one or more actuating signals for controlling actuators by means of corresponding actuators.

The sensors are, for example, the air mass meter 23 , a temperature sensor 51 for the lubricant 16 in the crankcase 15 outputting a signal T_OIL, a temperature sensor 52 for the coolant of the internal combustion engine 10 that outputs a signal TCO, a crankshaft angle sensor 53 , which detects a crankshaft angle, which is then assigned a speed N, a lambda probe 57 upstream of the catalytic converter 32 whose signal is characteristic of the air / fuel ratio in the combustion chamber 11 of the cylinder 12 , In a preferred embodiment is also a lambda probe 58 downstream of the catalytic converter 32 as provided in the 1 is shown in dashed lines. The signal of this lambda probe 58 can in particular for trim control and diagnosis of the functionality of the catalytic converter 32 be used. Signals from other sensors, which for the operation of the internal combustion engine 10 necessary, but not explicitly shown, are generally indicated by the reference ES.

The actuators are, for example, the throttle 22 in the intake tract 20 and the fuel injection valve 27 , Further signals for further actuators, which operate the internal combustion engine 10 are necessary, but not shown explicitly, are generally designated by the reference symbol AS.

Next to the cylinder 12 can still be provided more cylinders, which are also associated with corresponding actuators. The application of the method according to the invention is independent of the number of cylinders.

The control device 40 determines, inter alia, as a function of a load signal and the rotational speed N, taking into account the signals of said further sensors the appropriate ignition timing, the injection timing and the injection period. If a crankcase ventilation takes place, so also the fuel components, which evaporate from the lubricant, are taken into account in this calculation.

The control device 40 has an interface 54 to which a diagnostic computer and / or a workshop test device 55 can be connected. With the help of these devices, for example, as part of an inspection of the motor vehicle in a workshop information about a performed lubricant change, in particular the change of the engine oil of the control device 40 be transmitted.

This information is then taken into account in the control and regulation algorithms, in particular in determining the time for the next oil change.

Furthermore, the control device 40 with an instrument cluster located in the vehicle interior 56 connected, with the various information about the operating condition of the internal combustion engine and the vehicle visually and / or acoustically the driver can be displayed. The driver can with the help of this instrument cluster 56 also make inputs yourself, in particular also enter the information that a change of engine oil has taken responsibility, ie outside a workshop visit. The 2 shows in the form of a flow chart a method for plausibility of the oil change information. The method is started in a timely manner after a start of the internal combustion engine in a step S1. In a step S2, it is queried whether an oil change information in the control device 40 is present. For this, the state of a logical variable LV_OIL_CHG is queried. If the logical variable LV_OIL_CHG has the value equal to 1, it is first assumed that an oil change took place before the start of the internal combustion engine. The logical variable LV_OIL_CHG is set to the value 1 when in the workshop via a diagnostic computer or a workshop tester an oil change that has taken place is transmitted to the control device or the driver of the motor vehicle inputs such information manually via the instrument cluster itself.

If the logical variable LV_OIL_CHG has the value equal to 0, then this is an indicator that no oil change has taken place since the last shutdown of the internal combustion engine and the method is in a step S9 and called again at the next start of the internal combustion engine.

If the query in step S2 reveals that the logical variable LV_OIL_CHG has the value equal to 1, then in a subsequent step S3 it is checked whether certain enabling conditions for the plausibility check of this state of the logical variable LV_OIL_CHG are fulfilled. On the one hand, the temperature of the engine oil T_OIL must be above a threshold value T_OIL_THD ( 3 ), so that at all fuel out of the engine oil and on the other hand, there must also be a certain minimum of fuel in the engine oil, which is determined by an oil dilution model OIL_M, which models the fuel input and fuel output based on various parameters. In addition, the internal combustion engine must be in the operating range of idle LL or at least in idle operation. In the following, therefore, the term "idling phase" in addition to the actual idling phase at idle speed and a close to idle operation with a relative to the idle speed low increased speed understood.

In addition, no full load travel must have taken place immediately before the idle phase LL or idle operation. A possible full-load operation leads to an accumulation of exhaust gases or inert gases in the crankcase, which (almost) completely displaces the available oxygen. Exhaust gas or inert gas is incorrectly interpreted as air by an air mass meter or, in the case of a pressure-controlled system, by the pressure sensor. This causes fuel to be injected into the exhaust gas / inert gas in the cylinder. The lambda sensor after the cylinder, however, measures the oxygen concentration in the exhaust gas as a matter of principle. This sensor would now recognize a too rich mixture. However, this rich mixture exists because of the previous misinterpretation and not because of high oil dilution by fuel. For this reason, one has to make sure that no full load journey took place before the plausibility check.

If the release conditions are not fulfilled, then the queries are repeated, if appropriate after expiration of a waiting time T_WAIT in step S3, otherwise the method is continued in a step S4. There is the signal λ_CONT the lambda probe during the idling phase LL or the idle operating range 57 continuously detected and checked in a subsequent step S5, whether within the observation period of this signal λ_CONT falls below a predetermined threshold λ_THD. Since in the presence of fuel in the oil and subsequent outgassing an enrichment of the fuel-air mixture, this threshold is in the fat region, ie λ_CONT <1. "falling below" means in this context that the lambda probe signal λ_CONT by more than a predetermined value in the Fat area is moved.

If the result of the query in step S5 negative, so the threshold λ_THD is exceeded, it is assumed that the oil change information z. B. is present by an incorrect operation by the driver when entering the instrument cluster and the oil change information is not confirmed (step S8). That is, the previous entries in the oil dilution model are not reset, but the fuel input and fuel discharge are further modeled, and the process ends in a step S9.

If the lambda probe signal λ_CONT remains below the threshold value λ_THD, this is an indication that no fuel or only a small amount of fuel outgassed from the engine oil, from which it is concluded that an oil change has taken place and thus the oil change information is confirmed in a step S6. Therefore, in a subsequent step S7, the entries, i. H. the model parameters in the oil dilution model are reset and the logical variable LV_OIL_CHG is set to the value 0. The process is ended in step S9.

In the 3 different diagrams are shown to illustrate the method according to the invention. The lower part shows the state diagrams of the logical variables LV_OIL_CHG, LV_ES and LV_IS depending on the time t.

At a time t0, the internal combustion engine is started and switched off at a time t3. The value of the logical variable LV_ES (engine stop, engine stop) changes from 0 to 1 at this time t3. At a time t5, the internal combustion engine is switched on again, the value of the logical variable LV_ES changes from 1 to 0 at this time t5 of the operation of the internal combustion engine two idle phases LL1 and LL2 occur. The first idle phase LL1 starts at time t1 and ends at time t2, the second idle phase LL2 begins at time t6 and ends at time t7. During the idling phases, the logical variable LV_IS (idle speed, idle) has the value 1, and outside the idling mode the value 0.

At a time t4 receives the control device 40 an information that an engine oil change has taken place, either via the workshop tester or the diagnostic computer after a service call in the workshop or by the manual input to the instrument cluster by the driver, whereby the state of the logical Variable LV_OIL_CH changes from value 0 to value 1.

In the top diagram of the 3 the course of the temperature of the lubricant T_OIL and the course of the fuel quantity in the lubricant FM_OIL are shown. With the start of the internal combustion engine at the time t0, the temperature of the lubricant T_OIL increases and relatively quickly exceeds the threshold T_OIL_THD, which is selected such that outgassing of fuel contained in the lubricant is possible. Also increases during operation of the internal combustion engine, the proportion of fuel FM_OIL_in the lubricant.

Since upon entering the first idle phase LL1 there is still no information about a possibly occurring change of the lubricant (LV_OIL_CHG = 0) and a relatively high fuel fraction FM_OIL is present in the lubricant, the lambda probe signal λ_CONT shows a clear deflection into the rich region (λ <1 ) and the threshold λ_THD is exceeded.

The plausibility of the oil change information begins as soon as the engine returns to the next idle phase after entering the oil change information, here in the idle phase LL2. If the threshold λ_THD is not reached during the idle phase LL2 (solid line of the λ_CONT curve), then this is interpreted as an indication of a lubricant change actually taking place. If no change of the lubricant was carried out, although the corresponding information was transmitted to the control device, a curve for the lambda probe signal λ_CONT would be set during the second idling phase LL2, which is shown with a dashed line and essentially the course of the lambda probe signal λ_CONT during the first Idling phase LL1 corresponds.

The threshold λ_THD for the lambda probe signal λ_CONT can be used as an absolute λ value, z. B. λ = 0.85 to 0.80, or as a percentage value, if the value of λ = 1 λ = 1 is designated as 100% neutral value. A decrease in the λ-value by more than 15% or 20% would then mean that the oil change information is not confirmed.

If the oil change information is confirmed after expiration of the idle phase LL2, the model parameters in the oil dilution model are reset, in particular the value for the fuel fraction in the lubricant FM_OIL is set to a minimum value FM_MIN close to zero, as shown in the upper diagram in the course of FM_OIL.

The invention has been explained with reference to an example in which information about an engine oil change is made plausible, but it is also possible to carry out the process with any type of lubricant change, provided that the outgassing from the lubricant fuel has an influence on the amount of fuel to be supplied to the combustion chamber.

LIST OF REFERENCE NUMBERS

10

Internal combustion engine

11

combustion chamber

12

cylinder

13

piston

14

pleuel

15

crankcase

16

lubricant

20

intake system

21

air filter

22

throttle

23

Air mass meter, load sensor

24

vent line

25

Gas inlet valve

26

camshaft

27

Fuel injection valve

28

spark plug

29

gas outlet

30

camshaft

31

exhaust tract

32

catalytic converter

40

control device

41

Arithmetic unit, processor

42

program memory

43

Value memory, data memory

44

lambda controller

51

Temperature sensor lubricant

52

Temperature sensor coolant

53

Crank angle sensor

54

Interface workshop tester

55

Workshop tester, diagnostic computer

56

instrument cluster

57

Lambda probe upstream of the catalytic converter

58

Lambda probe downstream of the catalytic converter

λ_CONT

Lambda probe signal

λ_THD

Threshold for lambda probe signal

λ_NW

Neutral value lambda probe signal

LV_OIL_CHG

logical variable oil changes

LV_ES

logical variable engine stop

LV_IS

logical variable internal combustion engine idling

T_OIL

lubricant temperature

T_OIL_THD

Threshold for lubricant temperature

TCO

Coolant temperature

t

Time

t0

Start of the internal combustion engine

t1, t6

Time start idle

t2, t7

Time end idle

t3

Timing internal combustion engine off

t4

Time input "Oil change takes place"

t5

Timing internal combustion engine "on"

t8

Time Reset logical variable LV_OIL_CHG

LL1, LL2

Idling phase of the internal combustion engine

T_WAIT

waiting period

N

rotation speed

IT

Signals from sensors

AS

Signals for actuators

FM_OIL

Fuel quantity in the engine oil

FM_MIN

Minimum fuel quantity in the engine oil

OIL_M

Oil dilution model

OIL_P

Method for checking the plausibility of the oil change information

Claims (6)

Method for plausibilizing information about a change of a lubricant ( 16 ) in an internal combustion engine, the internal combustion engine comprising: - a crankcase ( 15 ), from which a vent line ( 24 ) into an intake tract ( 20 ) of the internal combustion engine leads, so that in certain operating conditions of the internal combustion engine in the crankcase ( 15 ) existing fuel vapor into the intake tract ( 20 ), - an electronic control device ( 40 ) for controlling and regulating the internal combustion engine with a lambda controller ( 44 ) and an oil dilution model (OIL_M) which determines the fuel input and fuel discharge into the lubricant ( 16 ), wherein - the control device ( 40 ) Information (LV_OIL_CHG) about a supposed change of the lubricant ( 16 ) is supplied, if a predetermined release conditions for the plausibility check in a subsequent idling phase (LL2) of the internal combustion engine, the signal (λ_CONT) of a lambda probe ( 57 ) is monitored, and - if the signal (λ_CONT) falls below a predetermined threshold (λ_THD), the information (LV_OIL_CHG) about the change of the lubricant ( 16 ) is not confirmed, otherwise the information (LV_OIL_CHG) is confirmed. A method according to claim 1, characterized in that the plausibility check is released when the temperature (T_OIL) of the lubricant ( 16 ) is above a predetermined threshold (T_OIL_THD). Method according to Claim 2, characterized in that the plausibility check is released when the proportion of the fuel (FM_OIL) in the lubricant ( 16 ) exceeds a predetermined threshold. Method according to one of the preceding claims, characterized in that with confirmed information (LV_OIL_CHG) via a change of the lubricant ( 16 ) Model parameters of the oil dilution model (OIL_M) concerning the entry of fuel in the lubricant ( 16 ) reset. Method according to one of claims 1 to 3, characterized in that the information (LV_OIL_CHG) about the change of the lubricant ( 16 ) is not confirmed when the signal (λ_CONT) of the lambda probe ( 57 ) differs by more than 15%, in particular by more than 20% from a neutral value (λ_NW). Device for plausibilizing information about a change of a lubricant ( 16 ) in an internal combustion engine, wherein the device is designed to carry out a method according to one of claims 1 to 5

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