What does the black oil in the engine say. Why does the oil darken

Recall that on a serviceable car, the oil suddenly turned into a thick black slurry, after which the motors were sent for a “capital” or replacement - untimely and extremely expensive. without even asking our permission. Well, that's okay...

Summary previous article - a wave of sudden engine failures has swept through branded car services (and not only), associated with incomprehensible and unpredictable behavior of engine oil. Without any warning, the oil suddenly turned into a black oil, began to burn out very quickly. The result - overhaul or death of motors.

The epidemic hit cars regardless of their brands and manufacturers. Cases of the disease were registered in Moscow, and in St. Petersburg, and in Magnitogorsk, and in Murmansk - that is, almost throughout the country. And it was also noticed that the “sick” were mainly cars serviced at serious car services, in which barrel branded oil was poured. The situation was aggravated by the fact that these cases were irregular, met infrequently, but with enviable regularity. And, as any diagnostician knows, it is the “floating” defect that is the most difficult to catch.

The cause of this illness was incomprehensible, there were only hypotheses, but you can’t build a lawsuit in court on them (and most often it was the case that reached the court in proceedings). And then we promised to try to deal with the situation and acquaint our readers with the results.

Six months of work of our testing laboratory was not in vain. We managed to simulate a number of situations in the laboratory and, finally, get clear manifestations of this “deadly disease”. The symptoms that we will catch are a sharp increase in viscosity, a drop in alkaline and an increase in acid number, the deposition of thick tar-like deposits on the engine walls that prevent oil from pumping through the channels of the lubrication system.

IS THE OIL IN THE CANISTER SEPARATED? IS THERE RESIDUE? TO THE WASTE!

FALSE TRAIL

Let's start with the typical "excuses" of dealer service stations, on the basis of which they are trying to fight off warranty repairs. The inquisitive mind of warranty specialists usually wanders in three directions - the use of low-quality fuel; antifreeze or water getting into the oil; lack of control over the oil level in the engine during operation.

Let's immediately remove the third option - it is obvious that even with a very small amount of oil in the sump, it should not change its properties in the way that we see in cases of advanced "disease". When using a “healthy” oil, the engine will react to its small amount by lighting up the control lamps on the dashboard and sound alarms. First - with rolls and sharp accelerations and decelerations, when the receiving fungus is exposed. Any normal driver will respond to this immediately. And after topping up the oil, you will not feel any negative consequences in the future.

The most common alleged "reason" on the basis of which they try to void the warranty is the use of substandard fuel. Substandard in the understanding of service station mechanics is either a low octane number, or a high sulfur content in the fuel, or the presence of a large amount of tar in it. Let's say right away that, apart from sulfur, everything else, according to the current Technical Regulations, which regulates the quality of fuel, is not subject to control, therefore, it is not subject to jurisdiction. But, since there are such attempts at excuses, we will check.

FUEL - JUSTIFY!

Several bench engines, initially completely serviceable, were doomed to the slaughter. It’s a pity for them, but these are just pieces of iron, and living people suffer from the problem. Therefore - let these motors serve for the benefit of people.

Especially for the experiment, not without difficulty, they got 100 liters of fuel, more like a bodyagi. Instead of the declared 92 octane number, only 89.5 were measured, the sulfur content went off scale over 800 ppm, the tar was more than 3.5 mg / dm3. The manufacturer is unknown, but in terms of quality it is something from some kind of "samovar" - an amateur mini-refinery that distills gas condensate into supposedly fuel. Worse than ever! You have to dislike your car very much to feed it with such good things.

We fed the engine all the bodyag we got. And, in order to completely aggravate the situation and provide the oil with the maximum possible contact with disgusting fuel, they broke off the side electrode on one of the candles. Now the fuel entering the idle cylinder will fly into the crankcase in large quantities.

The motor self-diagnostic system was indignant, the check-engin burned brightly and incessantly all the time of torture. The motor shook and vibrated, but... survived! His autopsy revealed no problems - everything was clean and no black deposits were observed anywhere. The oil pressure, of course, dropped a little - the dilution of the oil by the fuel affected. At the same time, as soon as the damaged candle was replaced with a normal one, literally half an hour later, the arrow of the oil pressure indicator returned to its previous position. It is understandable, gasoline is a volatile liquid, and at operating temperatures the oil into which it has entered will not live there for a long time.

Measurements of the physico-chemical parameters of the oil did not reveal anything unexpected! The viscosity of the oil dropped a little - after all, some fuel fractions of the so-called gasoline remained in it. The alkaline number slightly decreased - from 7.8 to 7.4 mg KOH/g. The acid number increased by 0.3 mg KOH/g. The flash point dropped noticeably - from 224°C to 203°C. This clearly indicates that there was gasoline in the oil! But he couldn't kill him...

Moreover, in a real situation, its diagnostic system will be indignant at the poor-quality feeding of the motor in the first place. And this indignation is sure to leave an indelible mark on the computer logs. But in almost all cases when the warranty services refused to repair, motivating their decision to use low-quality fuel, the diagnostic system did not confirm anything of the kind.

Verdict: Gasoline not guilty!

SUSPECTED WATER

Water always gets into the oil in some quantities! It condenses from the moist air entering the cylinders and, together with crankcase gases, mixes with the oil. Coolant can only get into the oil if there is a leak in the cooling system - and only when the engine is stopped. During its operation, the oil pressure is higher than the pressure in the cooling system, and therefore the path for antifreeze to the oil is closed.

Well, let's try to simulate this situation. 3 liters of fresh oil were poured into the long-suffering engine, and then a whole liter of water was thrown into it! And what? Never mind! Of course, an emulsion formed in the sump, the oil pressure dropped noticeably. But the motor worked, nothing critical was heard or seen. And then - gradually the oil pressure began to grow and soon returned to the initial level. What happened? The water simply evaporated, the oil returned to its original state. The autopsy of the motor showed no problems - everything was clean again. Changes in the physical and chemical parameters of the oil after the ingress and subsequent evaporation of water turned out to be within the measurement error! And this is the reason for the withdrawal from the guarantee - to refuse for insolvency!

After that, they dealt with a similar situation by replacing the water with antifreeze. The result is the same, the engine survived. But the viscosity of the oil has grown - it is understandable, the water has evaporated, and the ethylene glycol remains in the oil. The alkaline number decreased slightly, the acid number increased. Yes, of course, if you drive an engine with a broken cylinder head gasket for a very long time, constantly adding antifreeze to the tank and not trying to deal with the situation, then in the end, you can probably achieve the death of the oil, and with it the death of the engine! But this is just an extreme case of a disregard for the engine. Yes, and here there will already be a situation - not “ethylene glycol in oil”, but “oil in ethylene glycol”.

Conclusion - such a reason can only be considered when it was preceded by a long and constant loss of coolant in the engine. And with a complete lack of control of the condition of the oil at the same time. This is also not our case.

Verdict: It's not the coolant's fault!

GOT!!!

We checked two more versions. And, looking ahead, let's say - THEY WORKED!

The first one was suggested by oil specialists, with whom we constantly communicate. In their opinion, the picture that we are seeing, that is, a sharp increase in oil viscosity, may be associated with unexpected polymerization of some components of the additive package. The reason for this disgrace is the volumetric overheating of engine oil. And they remembered that at their seminars, some manufacturers of oils and cars, since recently, began to give a clear recommendation - if suddenly the oil was overheated, then you urgently need to run to the nearest service center and change it!

We tried to overheat the oil on a bench motor. It was not difficult for us to do this - we had to turn off the external engine airflow and select the appropriate operating mode. Unlike most cars, our sump oil temperature is constantly displayed on the control panel. Indeed, it rose by 20...25 degrees. This torture continued for many hours. Two oils worked fine, withstanding such a mockery. But the third behaved strangely - it began to noticeably thicken. And then, in the drain tank, where they left its remains for a couple of days, traces of oil separation were found. It drew the same “tar” that we observed on the walls of motors killed by oil. Both on the inner surface of the cylinder block and on the side surfaces of the pistons, there was much more contamination than usual.

So, we opened one option for the death of oil. But they didn’t experience much joy from this - after all, it’s not clear how you can track the real temperature of the oil in the sump in a living car? Indeed, in new cars, even the coolant temperature gauge was removed! It turns out that this information is not even redundant at all!

Let's go further... We remembered how it all started. It all started with a letter from our reader, who, having bought a canister of oil from a very well-known company for topping up, suddenly discovered in it ... an incomprehensible sediment! And from the answer of a technical specialist of the Russian representative office of this company, who, to our request for an explanation of the situation, literally uttered the following: “I hereby inform you that a small amount of sediment is allowed in motor and transmission oils. It can be caused by the association of fine catalyst particles that are smaller than the pores of the factory filter element. These sediments... can be up to black in color. They are rare and, as a rule, only in those batches of oil that were made immediately after reloading the fresh catalyst in the apparatus. They do not affect the performance characteristics of commercial oil and, subsequently, in the process of operation, they again turn into a finely dispersed state.

At one time, our oilers were shocked by this answer! That is, one of the world's main oil producers honestly admits the possibility of a gross violation of oil production technology!

And we compared what is written and what we saw with our own eyes. After all, the premature death of oil is very similar to the picture that we could see due to a sharp acceleration in the rate of oil oxidation. It is this process that is accompanied by an increase in its viscosity and acid number, a drop in base number. And what can contribute to the uncontrolled acceleration of the chemical reaction, which, in fact, is the oxidation of oil? Precisely the presence of a catalyst!

Yes, of course, when storing such a “dirty” oil, the catalyst will be silent - after all, to activate its work, it requires special conditions, temperature and pressure. But they are just in the active zone of the friction units. So, check this out too!

The main problem that has arisen before us is where to get this catalyst? Only the Russian representative office of MOTUL responded to our requests for help in this matter. It seems that only they, by the way, never exposed in cases of premature loss of oil, found it necessary to establish the truth! For this we sincerely thank them, and let them not consider our thanks as an advertisement for this company.

So, we have two options for the catalyst used in the production of hydrocracked base oil. We turned large granules of catalysts into a fine-grained powder of the desired fractional composition - such that it would fly through the pores of the oil filter. These powders were mixed with oil, and after half an hour they saw - here it is, a harmful sediment!

This oil was poured into the next engine, intended for slaughter, and a cycle of its long knurling began. At first everything went well, but after twenty hours of testing they began to notice that the oil pressure was dropping. And the oil on the dipstick became noticeably thicker - all the more, they initially used very good “synthetics” 5W-30, against its background, the increase in viscosity was especially noticeable! It's strange - the viscosity is clearly growing, and the pressure is dropping ... Maybe wear has appeared? But somehow this process progressed too quickly. The motor withstood only 40 hours of testing, after which the pressure completely disappeared. Then - everything, as usual, an autopsy, measurement, inspection.

The first thing that caught my eye was that from four liters of oil initially poured into the engine, only one and a half liters merged from it as a result of tests! And this is - in just 40 hours of very moderate modes, in terms of equivalent - less than 3000 kilometers! And the oil was terribly black. Measurements of engine parts did not reveal serious wear, although it was noticeable - the bearing shells and crankshaft journals were somehow very well polished. It is also clear - the catalyst powder worked as an abrasive. So why did the oil pressure drop so much? The presence of some solid agglomerates in the pallet immediately caught my eye, which sat firmly on the walls. These, apparently, were the very "harmless" according to the authors of the ill-fated letter "associations of fine particles." But they were clearly less than the volume of the initial sediment in the oil filled in the engine. We also did not notice particles in the filter. This means that the main part of the powder introduced by us into the oil has settled in the channels! This is the reason for the loss of pressure in the lubrication system.

And what did the analysis of the physico-chemical parameters of the oil that worked with this “harmless” powder show? The viscosity of the oil, which was originally 11.2 cSt at 100°C, has increased to 17.9 cSt! That is, the oil, which was originally in the SAE-30 class, jumped to the SAE-50 viscosity class in 40 hours! The acid number increased by more than 2.5 mg KOH/g. Recall that in the last resource examination for 180 engine hours, oils increased their acidity by only 0.75 ... 1.0 mg KOH / g! The base number decreased less, and the deposits on the walls of the crankcase were, although more than usual. Moreover, the oil at room temperature was so thick that it did not want to drain from the walls - we have not seen this before. By the way, the picture that we observed in our experiment was suspiciously reminiscent of the one that was given out by one of the oils during our previous “semi-synthetic” examination.

So, according to some oilers, "harmless" catalyst powder in a relatively short time ruined the oil and finished off the engine. And in this case, alas, even the “capital” will not help him - after all, removing the plugs that clog the oil channels, judging by the structure of deposits in the sump, will be extremely problematic. By the way, some conscious dealers of large automakers who encountered a similar problem changed either cylinder blocks or the entire engine assembly without talking.

The results already clearly show that neither automakers nor car owners are to blame for the troubles that have happened. After all, the thermal instability of some types of oil, leading it to polymerization during volumetric overheating, and the possible presence of an aggressive catalyst deposit in it, which is allowed by some oil manufacturers, are the most serious "punctures" of these companies.

Summing up, while intermediate. Of course, someone would like to hear a loud appeal: they say, do not buy oil from firms A, B and C! And buy D-oil: it never gets sick! But we did not look for the guilty switchman, but investigated the problem. In addition, ten thousand cars can happily run on company A oil, but ten thousand will be the first to get into an unpleasant situation. On the other hand, we technically competently substantiated the inconsistency of the on-duty attacks on the burdock driver. Moreover, we managed to find some possible causes of mass cases of accelerated oil and engine death in general.

We sincerely want to believe that oil and gasoline manufacturers will carefully study our conclusions: all motorists are waiting for this. In the meantime, we recommend using our recommendations on "Methods of Self-Defense", following which you can save the engine in a critical situation.

DROP SAMPLE

On any porous paper (optimally - a piece of a filter for a coffee maker or at least a piece of newspaper) from the oil dipstick of a cold engine, drip a drop of oil. If it quickly spreads over the paper, forming several concentric circles, then the oil is alive. But if it does not want to spread and remains a black drop at the point of fall - urgently replace it!

CAN'T CHECK OIL? FIND A PIECE OF NEWSPAPER!

P.S. It goes without saying that in the course of one of the next examinations of oils, we will separately analyze their resistance to the atrocities we have uncovered. One direction of search is already clear: a new wave of failures was noticed after one of the well-known refineries started working after modernization - after all, a similar catalyst is used in the production of high-octane gasoline!!! But doesn’t it come into the oil with this outwardly quite conditioned fuel? And from another region, information came about an allegedly accidental coincidence of the death of engines according to the scheme we described with the use of fuel containing an exorbitant dose of methanol, which is strictly prohibited in our country. This also needs to be dealt with.

HOT? TRAFFIC JAMS? CHECK THE OIL!

SELF DEFENSE METHODS

To protect yourself from possible trouble, we repeat our recommendations once again:

1. Use only oils purchased from trusted stores. For scheduled maintenance, it is better to come with your oil canister. After buying it, let it stand for a while, and, if possible, see if there is sediment in the canister. Usually the sediment can be seen on the transparent measuring strip on the canister.

2. Make it a rule, even if your engine is not noticed in increased oil appetite, at least once a week to get under the hood and monitor the level and condition of the oil on the dipstick. You should immediately be alerted by a sharp increase in oil consumption, or its sudden dilution, or, conversely, thickening.

3. Be especially attentive to the oil in the summer, when standing in traffic jams for a long time, or during long-distance high-speed hauls. It is then that volumetric overheating of the oil is possible.

4. Adopt the so-called. "drip test" of oil. Its essence and procedure are extremely simple. On any porous paper (optimally - a piece of a filter for a coffee maker, or at least a piece of newspaper) from the oil dipstick of a cold engine, drip a drop of oil. If it quickly spreads over the paper, forming several concentric circles, then the oil is alive. And, if it does not want to spread, remaining a black drop at the place of fall - urgently to the service station to replace it!

It is an integral part of any car with an internal combustion engine. It provides lubrication to all internal parts of the motor during operation. Without it, the car will not be able to work normally and the power unit will quickly jam. The choice of this fluid should be treated carefully and not delayed with its replacement. After a long distance traveled, it turns black and loses its main lubricating and protective properties. Most often, the replacement occurs once every five to ten thousand kilometers. But in some cases, car owners find black oil in the engine ahead of schedule. What is the reason for this phenomenon, we will discuss in this article.

Why does oil turn black?

New engine oil is often golden in color and has the full range of properties it should have. By the end of its service life, it becomes black and loses its qualities. Therefore, a replacement is necessary. But it also happens that car owners discover this much earlier, for example, after a thousand kilometers. They see that it has darkened, and some note third-party smells like the smell of burning. In fact, this phenomenon is quite common, and often there is a cause and a solution.

To understand this issue, first you need to talk about the oil itself and the properties of this substance. Today, a real product may include in its composition a lot of different kinds of additives that should improve the operation of the power unit. Some reduce the friction of the engine elements, others change the properties of the oil at different temperatures. But, among other things, there is one that regulates the alkaline number of the liquid. Alkali is extremely important in engine operation. It prevents dirt from settling on parts, neutralizes acids that enter the motor, and generally serves as a kind of cleaner for the entire system.

Here lies the answer to the question: “Why is there black oil in the engine?”. Some lubricants contain very little alkaline additives. Therefore, such engine oil cannot cope with all the dirt that has settled in the engine, which entails a number of negative consequences. In this case, the power unit can receive serious mechanical damage. Oil starvation, overheating of the motor with all the ensuing consequences will not take long.

But it also happens that black oil appears in the engine even when using highly alkaline and expensive samples. This happens in cases where car owners delay the replacement and drive tens of thousands of kilometers this way. Naturally, this has the most detrimental effect on the condition of the car engine and all internal parts. In addition, it clogs the system, which creates additional difficulties even after a new filling.

However, different liquids turn black at different times, and there are explanations for this. The first of these is clean and uncontaminated. In this case, there is simply nothing to contaminate the lubricant with and the operation will last the entire prescribed period. The second reason is motor oil with a low percentage of alkaline additives. In this case, the substance cannot do its job well and quickly absorbs the dirt that has entered the system, which is why dark oil appears in the engine.

What threatens black motor oil?

As practice shows, most car owners try to prevent blackening of engine oil and change it as soon as possible. The cleaner it looks, the calmer the motorist and the more confident he is in the health of his “iron horse”. But such an opinion was formed due to the long experience of car owners from the time when the quality of engine oil could even be determined. Then it was enough for motorists to look at the oil dipstick and understand whether it was necessary to replace this fluid in the engine or not. If the liquid was black, then they hurried to replace it so that the motor lasted as long as possible. Cheap motor oils then turned black very quickly, and after 1000 kilometers they had to be changed. This is due not to the presence or absence of any additives in their composition, but to the low quality of the product itself. The reason for this change in this case is clear. But is it possible to evaluate modern motor oils according to these criteria and will such an assessment be objective? We are inclined to believe that it is impossible to talk about the properties and qualities of such products based only on their color. To date, black oil in the engine does not indicate a low quality of the product and does not signal a replacement in the near future.

If the contents of the oil system do not darken even after long runs, then this cannot mean anything good. In such a situation, we can say that the product is not of the highest quality and does not clean the engine of dirt and wear products as it should be. The motor will become clogged, and dirt will settle in the system, which will significantly reduce its life. That is precisely why it is impossible to judge such modern products solely by their color.

The darkened liquid in the system means that it absorbed all the impurities from the system and prevented them from settling on the parts, thereby facilitating the operation of the power unit and increasing the resource. At the same time, if the substance is constantly pure, then this signals the reverse processes. Then we can talk about its inferior functionality, because precipitation from the engine elements is not cleaned and the resource is significantly reduced. So today the color of the oil still does not say anything. But there is another issue, which is that the lubricant darkens at different time intervals. We will discuss the reasons for this phenomenon below.

Causes of darkening of engine oil in the engine

Why does it happen that the same oil in different engines turns black at different times? Somewhere it happens earlier, and somewhere later. What is the cause of this phenomenon and is it possible to somehow influence it?

Many experiments were carried out and many cars were examined. And in the end, we came to the conclusion that the degree of contamination of the engine itself affects the darkening of engine oil. If the replacements took place regularly within the allotted time for this, then the amount of deposits in a small amount will not be able to significantly affect the color of the lubricants. This usually applies to cars with low mileage or new cars. A large amount of dirt has not yet accumulated in them and the oil does not take it into itself, changing its color.

In addition, on a car with approximately the same mileage and operating mode, the color of the liquid in the oil system can be radically different. This is due precisely to the quality of the product itself poured into the motor. If the oil in the engine darkened in one case earlier than in the other, then this can only speak of its low performance.

At the same time, in a heavily contaminated engine, oil with a high alkali content will turn black very quickly due to the fact that it “eats off” the dirt that has settled on the walls of the system well. Moreover, this can happen already after some 500 kilometers. A lubricant with a low alkali content, on the contrary, will remain light even after a much greater distance traveled, however, this does not mean that the lubricant is beneficial to the engine, and indicates its low contamination.

From all this there is a relationship, according to which it can be concluded that the black oil in the engine darkens faster in a contaminated engine, under the condition of a high alkali content. If this condition is not met, then the liquid will remain relatively clean and clean the motor more slowly.

Black motor oil in the engine and the possible consequences of its use

Is black oil in the engine so scary and what is it like? In fact, no harm is done to the motor if it is used. In addition, the set of functions assigned to it will be preserved throughout the entire service life. That is, in this case, the car owner should not have any problems, and from replacement to replacement (depending on the mileage indicated in the instructions), you can drive calmly. Darkened oil speaks only of a good cleaning of the oil system from all impurities that can destroy and damage it, causing heavy damage to the motor.

But it should be remembered that such highly alkaline samples have a relatively short service life and are not designed for long-term operation. Replacement is recommended no later than after 5000 kilometers.

Black oil verdict

If we consider black oil in the engine in terms of "good" and "evil", then this is more "good" than "evil". In this case, there is no negative load on the components and parts of the motor. On the contrary, a substance of this color may indicate that it does an excellent job of cleaning the engine of dirt and prolongs its service life. As we wrote above, clean oil after long runs can only be in two cases: if the engine has very low mileage and the car is new, or if a liquid with a low alkali content is filled in and it does not clean the engine elements well. So if you are the owner of a used car that has traveled more than tens of thousands of kilometers, and you see the same light liquid in the system as after filling, after several thousand kilometers traveled, then this is a reason to replace it with another one.

If you see that the lubricant has quickly darkened, then do not worry and drive calmly from replacement to replacement. This means that it does an excellent job with the tasks assigned to it and extends the life of the motor. Just make regular oil changes in your car and it will definitely serve you a long and faithful service.

Any motorist is well aware that for a long and trouble-free operation of the engine, it is important to periodically change the engine oil. If it has become dark in color, then it's time to replace it with a new one. Professionals recommend replacing immediately after the pressure drops in the motor or the check lights up. If there are serious problems with engine oil, the engine may simply not start. If you don't want your engine oil to turn black, take the car manufacturer's recommendations seriously. The engineers calculated the optimal replacement intervals, on average they are 5000-15000 km of run.

Advice! It makes no sense to spend money on a replacement in a car with low mileage, because this will not affect the quality of the engine, but it guarantees you unnecessary financial problems.

If after 20-30 km after the replacement, the normal color of the oil in the engine disappears, a black color appears, then immediately contact a car service.

Why does it turn black after a change

A similar phenomenon is possible when, when replacing the old composition, you did not completely drain it.

Attention! Even with careful draining of the used mixture, there is a high probability that 1-2 liters of the substance will still remain in the engine.

Some experts advise vacuum draining the oil in order to remove the old from the car engine as much as possible. This technology makes it possible to maximally draw out the spent composition from nodes that are inaccessible to a standard drain, but there is still no 100% removal of the mixture.

Attention! To carry out the replacement of mining using the express method with a vacuum pump, preferably after 5000-15000 km of run, this will ensure a complete renewal of the motor composition.

The best option for updating the oil is the alternation of several drain methods. The replacement algorithm is presented in the following video:

So that the color of the oil in the diesel engine does not change, it is replaced by a standard drain. To do this, the car is put on a lift, mining is removed into a special container, and after cleaning the engine, a new one is poured.

In addition, the oil in the engine takes on the color of gray sour cream in the presence of a dirty filter, if it is not changed in a timely manner. Manufacturers of modern filters have equipped them with special valves, thanks to which you can get rid of the problem of insufficient supply of the substance to the motor even when the filter is clogged. This situation does not cause negative consequences for the motor itself, but filter replacement is still necessary. If you find a black mixture on a dirty dipstick, you need to wipe it with a rag, then recheck. If the pressure will fully comply with the standards, and the color will not change, therefore, there is no reason for alarm.

Among the situations associated with a change in color to black or gray, we note:

Advice! Try pouring a special cleaning agent into the engine, using it to clean the car engine. Use such a composition carefully, otherwise the engine gaskets may be corroded, the pressure in the engine will drop, or the engine will not work at all.

Prevention

In order for the oil to retain its honey-brown color, it is important to fully comply with all the instructions of the car manufacturer: control pressure, change old oil to new oil in a timely manner. Black color is typical for cars that often get into traffic jams, and their owners have to replace them much more often. If problems are identified, immediately carry out a full diagnosis, otherwise the movement by car will be dangerous.

Black oil in the engine

Black oil in the engine causes complete panic for many motorists. They make claims about the quality of the product to the masters of service centers and sellers. In fact, its color can change for various reasons. What are the main causes of blackening? Modern brown engine oil may be due to special additives that reduce friction and change temperature characteristics.

For example, oil in a latte-coloured engine may be due to the use of lye.. This caustic chemical is introduced to neutralize the acid, as well as to prevent deposits (soot, dirt) from appearing in the engine.

There are also special additives that improve the quality of the oil. Without them, “oil starvation” occurs, the temperature regime of the motor is disturbed, it overheats, the oil channels become clogged, the camshaft is disrupted, and the liners rotate incorrectly. With prolonged use of a composition with a high alkali content, it may turn white. If during operation it darkens, this is considered the norm. Professionals say that if, after prolonged use, the engine mixture remains transparent, this is bad. As the main problems, they emit an insufficient amount of oil, which can lead to rapid wear of car engine parts.

Conclusion

In the motor, the movement of oil is carried out in a circle. With the help of a pump, the mixture is pumped from the crankcase, then it is passed through all oil channels. As it moves, it should lubricate all the parts of the car engine, the excess settles, the waste is gradually removed from the engine. Therefore, answering the question of what color the oil should be in the engine, we note that its gradual darkening is considered the norm.

Do not forget that when the engine is running, the oil is heated to a temperature of 120 degrees, resulting in a lubricating effect, accompanied by its darkening. If the substance becomes like fuel oil, after wiping the probe, black stains remain, then it is burning in the engine. The reason for this phenomenon is often the wear of the piston system. Any excess fuel not burned in the cylinders ends up in the oil. It changes its composition, color, becomes unusable. In such situations, a change in the color of the engine mixture is an alarm. There is a decrease in the power characteristics of the motor, fuel consumption increases. If the oil was chosen incorrectly (without taking into account viscosity), the engine may constantly overheat.

The quality and shade of engine oil is one of the most important and discussed issues among car owners. What should be a good oil? How often should it be changed? What to do if its color or consistency has changed? What are the consequences of using this oil? Does this lead to engine problems?

Normal engine oil: what should it be

The quality and color of engine oil depend on many factors:

• fuel quality;
• serviceability of the car engine;
• the quality of the oil itself;
• conditions in which the car is operated;
• the frequency of its change;
• additives added to its composition;
• base used.

There is no particular problem that the oil changed its color from amber to dark or black after 4-6 thousand kilometers. The car owner should start to worry if it starts to foam or thicken.

Is it possible to drive if the oil has changed its color and viscosity

If the lubricant has darkened, then you can ride it. Moreover, if after several thousand kilometers the oil has not changed its shade to a darker one, then it needs to be changed - it does not cope with its functions and transfers all the soot to the engine.

The blackening of the oil does not force it to be changed immediately. In the paperwork for the car, the manufacturer indicates the intervals for replacing lubricants. It is advisable to follow the recommendations, but at the same time, it is worth considering the individual characteristics of the vehicle and the mode of its operation - for example, if the car often has heavy loads, the period for replacing consumables is greatly reduced.

The most terrible change in engine oil is its thickening. If grease does not drain from the dipstick, and in consistency it resembles grease or boiled condensed milk, then things are bad. It is necessary to carry out a replacement in the near future, otherwise the engine will run dry, which will lead to deformation of the valves, connecting rods and pistons.

Why does the color change

All motor oils contain detergent additives. Such additives are used to dissolve products resulting from incomplete combustion of fuel. When the products of combustion are dissolved, the oil acquires a characteristic black tint. Despite the fact that soot particles are in suspension, this does not affect the lubricating characteristics of the lubricant. Accordingly, the driver can use the oil for a long time before a scheduled change.

You should start worrying when the oil does not change its color even after a long time of operation. This is not a sign that there is no contamination in the engine: the oil simply does not cope and cannot clean them. In this case, it is necessary to change the lubricants to new ones, preferably of a different brand.

It is worth paying attention to the timing when the grease begins to blacken. If the color changes immediately after filling, then either the engine is too dirty or the fuel used is of poor quality. Correcting this situation is simple - just flush the engine and start refueling the car in another place.

Reasons why it gets dark in the engine

1. Wear of the cylinder-piston group, due to which the combustion products of the fuel enter the crankcase;
2. Oxidation products of low-quality oil with a small amount of additives. Such compounds, reacting with air, are easily oxidized;
3. Old oil left in the engine. It is impossible to completely get rid of it - a certain amount of it will still remain in the nodes of the car. Accordingly, if it was black, then when mixed with a new one, it will also change its shade to a darker one;
4. The amount of additives in the composition of the lubricating fluid. The action of special additives is aimed at reducing friction and dissolving contaminants, so the quality composition may darken over time, since it performs its functions of cleaning the engine;
5. Overheating of the power unit can lead to boiling and blackening of the lubricant up to a change in its consistency, that is, in this way it is easier to thicken the oil;
6. Low quality engine oil that does not cope with its functions.

What can the use of dark oil lead to?

Darkened oil does not harm the engine and vehicle components. A change in the color of the lubricant means that it performs its functions and cleans the motor. The only thing to do is to change the oil to a new one in time according to the manufacturer's recommendations, taking into account the peculiarities of operation.

Foaming: what's the problem?

The formation of air bubbles can lead to various negative consequences:

• Reducing the viscosity of the lubricant composition;
• Slow removal of thermal energy, due to which the parts and components of the car will not be properly lubricated. The oil in the system moves through special channels of small diameter, and high pressure must be maintained in them to lubricate the engine;
• Lack of proper cooling of the parts of the power unit, leading to its overheating;
• The friction between the motor parts increases, which leads to their rapid wear. In the most advanced cases, this can lead to water hammer and engine overhaul.

Engine oil can foam for several reasons:

• Penetration into the lubrication system of antifreeze transport due to damage to the gasket between the cylinder block and its head;
• Water entering the lubricant, which leads to a change in its chemical composition and the formation of an oil emulsion;
• Lubricant incompatibility. When changing the oil, it is impossible to completely drain the old one, because of which it can mix with the new one.

Depressurization of the cooling system

The reason for the appearance of foam in this case is the mixing of oil and antifreeze. In most cases, this is due to defects in the gasket located under the cylinder block cover. Antifreeze can mix with engine oil if parts are defective. Cracks in them are formed due to metal fatigue or prolonged exposure to high temperatures.

An antifreeze leak is diagnosed simply: it is enough to evaluate the smoke from the exhaust pipe. To do this, the engine idles for 10-15 minutes, after which the exhaust pipe is covered with a white sheet of paper. The sheet is carefully dried and checked for stains of gasoline or oil. You can talk about a violation of sealing if there are no traces on dry paper. This can only be eliminated by contacting a service center, since it is almost impossible to find an antifreeze leak on your own.

Various engine oils

Foaming is characteristic of mixing two oils that differ in composition and properties. The main reason for this is the mixing of synthetics and mineral oil. This happens due to the difference in the structure of the two types of lubricating fluids: mineral oils are inferior in their properties to synthetic ones, which are formed as a result of catalytic synthesis reactions and the structure of which includes molecules of the same size located at the same distance from each other. Mixing two different types of lubricant leads to the formation of sediment, which, circulating in the engine, forms air bubbles. Foaming is eliminated in the only way - using engine oil of the same type and preferably the same brand.

Condensate

When water enters the engine or its parts, the latter mixes with oil, forming an oil emulsion. It does not have a negative effect and is not the cause of malfunctions, but indicates low-quality oil. Most often, the emulsion is formed in the winter season: a poorly warmed up car leads to condensation on the engine. Eliminating the formation of moisture is simple: it is necessary to thoroughly warm up the car before each trip in the cold season.

Consistency change

Engine oil thickening is the most dangerous problem. The consistency of the lubricant can be like condensed milk, grease or even plasticine, the latter lead to negative consequences for the car:

• The car engine starts poorly, stops responding to pressing the accelerator pedal. At the same time, the pressure indicator on the dashboard is constantly on;
• The connecting rods of the engine can break away from the pistons and break through the wall of the cylinder block, which disables the entire engine.

The exact reasons for the change in oil consistency have not been identified, but there are several basic assumptions:

• Mixing engine oil with water or coolant, resulting in the Shell effect. It is named so because the experts of this particular company discovered in the 40s the presence of traces of antifreeze and water in the thickened oil. It should be noted right away that not all oils will change their consistency even under similar conditions, however, the presence of water and antifreeze in the composition is a possible cause of thickening of the lubricant;
• Low quality fuel. According to the theory, the products of combustion of such gasoline can be mixed with oil, reacting with additives, which causes thickening. It should be noted right away that this reason is one of the most dubious and is still in question. Low-quality fuel is unlikely to have a strong effect on oil: it enters the crankcase in minimal quantities and does not stay there for long, since the evaporation temperature of gasoline is lower than that of oil. In addition, mixing fuel and oil leads to a decrease in the viscosity of the latter, and not to its increase. In addition, changing the consistency of the lubricant also disables diesel engines;
• Human factor. A common cause associated with filling low quality grease or a composition that has nothing to do with oil.

Why viscosity decreases and how to quickly deal with it

Engine oil not only thickens, but also loses its viscosity. There may be several reasons for this:

• Thermal cracking. During this process, the fractions and components of the lubricant decompose into components, which reduces the viscosity of the composition. The main thing is that their boiling point becomes lower, respectively, they practically do not ignite and evaporate faster;
• Contamination of the lubricant with substances that enter the engine along with the fuel;
• Mixing grease with special solvents that are used to clean the power unit before changing the oil. It is impossible to completely drain such compositions;
• Mixing oils with different viscosities. Filling in a new lubricant can lead to this: an incompletely drained old one can adversely affect a new, even branded, fluid.

You can eliminate all these phenomena in one way: replacing the engine oil. It is not entirely easy to do this on your own, especially if a complete cleaning of the entire system is required. The easiest way is to carry out the entire procedure in a car service, where the car will be lifted on special equipment, the system will be washed and new oil will be poured in, the viscosity of which will be checked immediately after the repair work.

What to do if the oil resembles solidol in consistency

The most terrible for the engine is excessive thickening of engine oil. If in its consistency it resembles grease, then this is the reason for immediately contacting the auto center.

Thickening of the oil to such an extent can occur for various reasons:

• Polymerization. Under the influence of high temperature, the components and components of the lubricant begin to stick together;
• Oxidation of oil that reacts with air;
• Long-term use of grease without regular replacement can lead to the accumulation of a large amount of soot and oxides in its composition;
• Formation of water emulsions leading to oil coagulation.

How to eliminate and prevent thickening of the lubricant

• Regularly check the operating temperature of the engine;
• Check fuel combustion efficiency;
• Do not allow water and antifreeze to get into the oil;
• Use only high-quality original compositions recommended by the car dealer.

If the consistency of the oil still changes, then you should immediately contact a car service.

Changing the color and consistency of engine oil can be a source of problems. Many of them are eliminated on their own, to get rid of others you will have to contact a car service. You can avoid malfunctions of a gasoline or diesel engine if you use only high-quality branded engine oil and follow the recommendations of the car manufacturer.

Owners quite often note such a phenomenon when fresh engine oil quickly turns black after replacement. A burnt smell may also appear in the oil, which is clearly felt after 200-500 km. run. In a similar situation, many drivers are wondering if the engine oil should turn black and how quickly this happens.

At the very beginning, it should be noted that there may be several reasons for the blackening of the lubricant. In some cases, rapid darkening is normal, while in others it may indicate certain problems with the engine or the poor quality of the engine oil itself. In this article, we will look at the main reasons why oil quickly turns black, and also answer the question of why oil turns black in a gasoline or diesel engine.

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Engine oil darkens

Let's start with the lubricant itself. It is well known that any motor oil is a mineral, synthetic or semi-synthetic base base, which also contains a package of active additives. These additives make it possible to comprehensively improve various performance characteristics of the lubricant: reduce friction losses, stabilize temperature indicators, extend the life of the oil and slow down its aging, provide a washing effect, etc.

In the list of chemical additives in the base base, a separate place is occupied by the indicator of the base number of a particular engine oil. In other words, alkali must be present in the lubricant. The main task of this additive is to neutralize acids that are formed in the internal combustion engine during the operation of the unit and then enter the lubrication system. Alkaline additives also actively fight the formation of deposits in the motor, wash off carbon deposits, coke, etc. Simply put, the alkali in the composition of engine oil protects against oxidation and performs detergent properties, allowing you to keep the power unit clean from the inside.

It turns out that the ability of the oil to wash off pollution will directly depend on the base number indicator. Given this feature, then the widespread assertion that high-quality car oil should practically not darken in the first 3-5 thousand kilometers after replacement is a profound delusion. Usually, drivers who dealt with similar products 15-20 years ago used to evaluate the quality of oil only by the rate of darkening. The fact is that in those years there were fewer additives and high-quality oil differed markedly from more affordable analogues in terms of pollution rate.

Simply put, the blackening of the oil was one of the main indicators for its replacement. Cheap lubricant could begin to darken after 400-800 km, while more expensive options remained clean for 2-3 thousand km, then gradually darkened to 5 thousand km. and then blackened. Note that the color of the lubricant did not change as a result of the action of additives, but taking into account the properties of the base oil. Today, the situation has changed dramatically, as modern motor oils contain a large number of active additives.

Darkening of the oil indicates that the lubricant retains and binds chemical components, deposits, etc. It turns out that acids do not have contact with parts, corrosion slows down and engine wear is minimized. During the process of changing the lubricant, contaminants merge with the used oil, and do not settle on the surfaces of the parts. In other words, everything turns out exactly the opposite - if the oil does not turn black for a long time, then it does not wash or clean the engine, and does not provide reliable protection against harmful products. The long transparency and purity of the oil indicates that the lubricant is simply not capable of performing cleaning functions.

It is also useful to know that if there are few alkaline additives in the composition of the lubricant, then if the service interval is exceeded, the engine will be subject to intense contamination and accumulation of deposits. In some cases, these contaminants lead to a decrease in the throughput of the channels of the lubrication system, as a result of which the pressure in the system decreases, the lubricant is supplied to the loaded friction pairs in insufficient volume, oil starvation and increased wear of the power unit occur.

In parallel with this, the temperature regime is violated at the interface points, an increase in the friction force leads to overheating. Also, clogging of the channels of the oil system does not allow the circulating lubricant to fully ensure heat dissipation. As a result, internal combustion engine parts are damaged, crankshaft connecting rod or main bearings turn, rockers fail, hydraulic compensators become clogged, etc. It is for effective counteraction and prevention of possible consequences that manufacturers add alkaline additives in a balanced way. We add that immediately after fresh lubricant enters the engine, the active work of the additive begins, that is, the lubricant ages. With mileage, the additive gradually loses its properties, the degree of protection of the engine from acids and deposits deteriorates, which is the reason for the next oil change.

It turns out that the service life of a modern lubricant is determined not by color, but by the indicator of how long the alkaline detergent additive will be in working condition. This feature is one of the main reasons why the lubricant must be changed taking into account strictly defined intervals (on average, 10-15 thousand km in the CIS, which depends on the quality of the fuel). It becomes clear that the oil is intended not only for lubrication, but also for cleaning. For this reason, its darkening during operation can be considered quite normal.

Note that the grease darkens especially quickly in motors that were initially contaminated. In other words, darkening means that the oil is actively washing the engine. Given this fact, the purity of the oil should be more alarming, that is, when its color practically does not change with mileage. This may indicate that the lubricant has low detergency and the engine is not being cleaned.

For a better understanding, it is enough to recall the features of the work. Engine oil is pumped from the engine crankcase using an oil pump, then circulates through separate channels. The lubricant protects the parts from dry friction, while carbon deposits and deposits are washed off, which then enter the crankcase. You also need to take into account the high temperatures at which the oil operates. As a result, the color of the material gradually changes to a darker one and this happens in a short period of time.

Engine oil turns black quickly

As already mentioned, the darkening of the oil indicates that it is working, that is, it actively cleans the engine of contaminants. It also happens that the oil does not just darken, but becomes black and more like fuel oil. In this case, this moment should be given special attention and find out why the oil in the engine turns black quickly.

1. At the very beginning, you need to remove the oil dipstick and wipe the oil from it with a clean rag. The remains of black stains will indicate that the lubricant in the engine is fading. The reason may be significant wear, that is, oil enters the combustion chamber. In parallel, the fuel also flows into the engine boat, diluting the lubricant. As a result, the working fluid of the ICE lubrication system loses its protective, detergent and other useful properties. It turns out that the rapid blackening of the oil indicates a problem with the engine itself. Additional symptoms are usually increased fuel and oil consumption, reduced engine power, difficult cold starting, etc.
2. The second reason that explains why the oil in a diesel engine quickly blackens or blackens the lubricant in a gasoline unit is overheating of the oil. A rapid color change to black occurs if the motor is constantly operated in heavy duty at high speeds and maximum loads. Also, the oil overheats when the lubricant was initially incorrectly selected according to the viscosity characteristics. In fact, boiling occurs, the lubricant becomes a homogeneous black mass.

It becomes clear that in case of problems with the CPG, the motor needs repair. If the oil is not suitable for this type of engine, then such a lubricant must be immediately replaced with a suitable option, which is recommended by the engine manufacturer and meets all tolerances. You should also not forget that a low-grade fake can be accidentally poured into the motor. For this reason, it is recommended to purchase fuel and lubricants only at trusted points of sale.

Remember, further operation of the engine with black oil can lead to serious damage to the power unit in the absence of existing problems, as well as additional problems when postponing repairs and lubrication changes on units in which oil blackening is noticed due to wear of individual elements.

How fast should engine oil turn dark or black?

So, all oils, regardless of types and brands, darken sooner or later. In this case, one product may blacken earlier or later than the other. Note that the darkening rate is influenced by a number of general and individual factors, among which experts distinguish:

• the condition of a particular engine and the cleanliness of its lubrication system;
• the amount of detergent additives in a particular lubricant;

It is quite obvious that if the lubrication system already has various deposits in the channels, then accelerated blackening can be considered normal. Moreover, the more detergent additives in a particular type of lubricant, the faster the lubricant will darken. It should also be borne in mind that after pouring fresh lubricant, it begins to actively wash off old deposits, which then accumulate not only in the oil itself, but also in. This means that during one service interval with rapidly darkening grease, it is better to change the filter twice or more. The replacement interval itself can also be reduced by 20-40%.

This approach will allow you to "softly" remove deposits that circulate through the oil system. In other words, the engine is gradually washed by the engine oil itself, which is changed prematurely, that is, before the start of the loss of cleaning properties. We add that for high-quality cleaning it may be necessary to carry out the procedure for replacing filters and oil according to this scheme not once, but several times.

Another cleaning method is the use of flushing into oil, as well as a short operation of the internal combustion engine on the so-called flushing oils. Note that these methods have both advantages and disadvantages. In short, flushes have a negative effect on rubber seals, and can also lead to various unpredictable chemical reactions after mixing with the base lubricant.

An additional nuance is that after softening the deposits in the engine under the action of flushing, they can clog the channels of the lubrication system. In such cases, the risk of premature failure of the working power unit increases. If the oil began to quickly turn black due to the ingress of gases into the crankcase, then the motor needs to be replaced or.

In view of the foregoing, we can conclude that if the oil turns black, but the lubricant consumption remains normal, then you can start by cleaning the oil system. After removal of contaminants, the rate of blackening should return to normal or slow down noticeably. If there are problems in the mechanical part, then the problem will go away only after the repair of the power unit.

What is the result

As you can see, the rapid darkening of the oil today cannot be considered a sign of its poor quality. If the motor is in good condition, then the rate of change in the color of the lubricant to dark or black will depend on the degree of contamination of the engine and the base number of the oil used.

Under the same conditions, oils with fewer alkaline additives will darken more slowly and wash the engine worse than their highly alkaline counterparts. At the same time, a lubricant with high detergent properties can darken after 300-400 kilometers traveled. In parallel with this, the darkening of the oil does not mean that it is time to change it. Active additives and alkalis wash and then hold the dirt in the oil, allowing the lubricant to work throughout its declared service life.

We also add that when choosing a lubricant, a number of additional features should be taken into account, and not just its detergent properties. The fact is that oils with a high alkaline number have a short service life (on average, about 6-7 thousand km). The fact is that such products usually do not contain a large amount of additives that slow down the aging process of the lubricant. In other words, an oil with good detergency is designed for a shorter life and is subject to accelerated oxidation and aging, which means shorter intervals and more frequent changes.

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