What will happen if you do not change the oil in the engine: the consequences in the photo. Changes in the consistency and color of engine oil: causes and remedies Engine oil has turned into a gray liquid

29.09.2019

Salon

At the same time, during the next check, in some cases it can be found that the oil is liquefied and drips from the dipstick, it has turned very black, it has become viscous and looks more like grease, foam is noticeable in the oil, etc.

Naturally, in such a situation, it is important to know why the oil has changed color and its structure, as well as what consequences further operation of the engine with such a lubricant can lead to. Let's look at these issues in more detail.

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Engine oil turned black

Let's start with the color of the lubricant. As a rule, and closer to the end of the service life, it may even turn black. At the same time, the darkening of fresh grease occurs quite quickly (after 200-300 km of run). First of all, it must be borne in mind that the lubricant, in addition to protective ones, also has detergent properties. This means that various deposits, fuel combustion products, soot, etc. accumulate in the lubricant.

Moreover, the rate of blackening is influenced by the degree of contamination of the vehicle itself, its condition, as well as the individual characteristics of the operation of the vehicle. For example, if the engine is running under severe conditions, there are problems with the combustion of the mixture in the cylinders, then the fuel leaves a lot of soot and other particles that are not completely burned out. These contaminants accumulate in the lubricant, deteriorating its properties and changing the color of the oil.

Usually, the mineral and semi-synthetic base darkens and ages the fastest, synthetics and hydrocracking remain in the normal state longer. It is important to understand that the darkening of the oil is the norm.

Pay attention if the grease does not darken and does not change color after several thousand km. mileage, then this indicates a low quality oil or an outright fake. In practice, light motor oil with a mileage of about 1.5-2 thousand km. indicates that there are no detergent properties, there is no ability to retain deposits and soot, that is, contaminants continue to accumulate in the lubrication system and are not captured by the oil itself.

It turns out that if the oil turns black, this is not a reason for its immediate replacement. You can change such a lubricant a little earlier than the due date, taking into account the recommended replacement interval or adjusted for individual operating characteristics. In the latter case, heavy loads on the internal combustion engine and a reduction in the planned replacement interval by 30-50% are assumed.

So, with regard to the causes of darkening, in view of the foregoing, it becomes clear that blackening of the lubricant causes:

low quality fuel;
violation of the processes of combustion of the working mixture;
oil quality, cheap base;
low content of detergent additives;

With regard to the rate of browning, the intensity of the color change is due to the quality of the oil, the condition of the engine itself, as well as the intervals for changing the lubricant. It should also be added that fresh grease may turn black due to the fact that the old oil cannot be completely drained from the engine when replacing. The result is a mixing of residues that change the color of the newly filled grease.

Engine oil thickened

Having dealt with the blackening, let's move on to why the driver can detect grease in the engine. First of all, motor oils today are all-weather, have the so-called high and low temperature viscosity (for example, 5W30, 10W40, etc.).

This means that a lubricant of one type or another involves operation in a certain temperature range. At the same time, if the high-temperature viscosity is not so noticeable to the driver, obvious problems with cooling can arise precisely because the oils thicken in the cold.

In other words, at low temperatures, the liquid loses its fluidity and in some cases becomes similar to grease. We add that usually it can thicken so much, and also a counterfeit fake.

In other cases, oil in cold weather may be pumped worse through the lubrication system in the first seconds after starting, but then the situation normalizes. One way or another, the lubricant should be selected taking into account the characteristics of operation and weather conditions. This will help minimize . As a rule, high-quality synthetics and show the best results.

However, it must be taken into account that an increase in viscosity can occur both depending on temperature and for other reasons. Moreover, this situation is much more dangerous and you need to figure out why the oil in the engine is like grease.

Let's start with the simplest. In a nutshell, any oil tends to "work out" over time. Moreover, if you use the lubricant for a long time (significantly increasing the recommended replacement interval), then the used oil completely loses its properties, accumulates a huge amount of contaminants and turns from a fluid liquid into a gel-like substance.

In this case, no dilution occurs even after the engine warms up. The result is the strongest wear of all parts of the power unit, the appearance and, in some cases,. Often leads to such consequences.

In practice, the driver can change the lubricant every 15 thousand km, as prescribed in the manual. However, taking into account the fact that the car often and for a long time stands in traffic jams, the unit idles for hours, etc., the mileage can fit within the specified limits, but according to engine hours, such oil has worked out for a very long time. As a result, instead of a fluid liquid, a substance similar to grease was formed in the internal combustion engine.

Another reason for such dangerous changes in engine oil is polymerization. In simple words, the components are glued together, that is, the lubricant “curls” from high heat.

We also add, in some cases, as well as the accumulation of condensate in the crankcase also leads to the fact that the lubricant loses its properties, an emulsion forms in the oil and it coagulates.

In parallel, we note that some motorists practice, and also use, to supposedly improve the basic properties of the oil and avoid diluting it. Cases have been noted when such experiments made the engine oil too thick, with all the ensuing consequences.

Engine oil is too thin

Excessive dilution of engine oil can also often occur as a result of aging of the lubricant itself or engine overheating. One way or another, the “viscous” components break down into tiny particles.

In all cases, liquid oil leads to the fact that the pressure in the lubrication system drops, the oil film becomes too thin and the protection of rubbing surfaces deteriorates significantly, metal parts wear out quickly from friction.

We also add that use followed by incomplete draining can change the viscosity of a recently filled fresh lubricant in the direction of dilution. If flushing oils or aggressive five-minute flushes were used, it is advisable not to load the engine and reduce the subsequent relubrication interval by 30-50%.

Engine oil foams

Another common problem that a motorist may encounter is. As a rule, the simplest reason may be.

Also, the appearance of foam and emulsion occurs if the liquid from the cooling system is mixed with engine oil. The lubricant also foams if there has been a mixing of lubricating fluids that differ in properties and additive packages. Under the influence of temperature, foaming occurs.

Often, as part of urban operation in winter, the engine does not have time to warm up to operating temperatures in a short trip. As a result, condensate collects in the pan. The same thing happens if the machine is rarely used. In any case, the condensate mixes with the oil, after which foam appears.

Summing up

As you can see, proper operation of the car involves constant monitoring of the level and condition of all technical fluids. At the same time, engine oil is the first on the list, since malfunctions of the lubrication system lead to the rapid occurrence of serious and costly breakdowns of the internal combustion engine.

For this reason, any change in the consistency of the oil, a decrease or, conversely, an increase in the level of lubrication, the presence of an emulsion, foam, clots, excessive contamination or the absence of darkening with mileage is a cause for concern.

What should be normal engine oil

The color and quality of the oil is influenced by many factors:

engine health,
fuel quality,
vehicle operating conditions
the quality of the oil itself,
frequency of replacement.

If the oil changes color from amber to black after 4000-5000 km, this is not a big problem, and you can continue to drive. But if it foams or thickens, the car owner has a reason for concern. Let's look at each case in detail.

Why does it turn black

Every modern engine oil contains one or more detergent additives. They are needed to dissolve the products of incomplete combustion of gasoline. In other words, to wash away soot. Dissolving, it gives the oil a characteristic black color. Soot particles are suspended in the oil substance, but this does not significantly affect the lubricating properties of the oil, so the driver can continue to use it until the time for a scheduled oil change comes up (the frequency of the procedure depends on the brand of the car and is indicated in its operating instructions). A cause for concern appears when the oil remains clean even after long-term operation. This does not mean that there is no contamination. This means that the oil used by the driver is not able to wash them off, and they remain on the internal surfaces of the engine. If such a picture is observed, another brand of oil should be used. The only point worth paying attention to is the darkening time. If the oil becomes dark almost immediately after filling, this indicates either serious engine contamination or poor fuel quality. In the first case, it is recommended to additionally flush the engine, in the second - to refuel in another place.

What made it foam

Oil foaming requires the immediate intervention of the car owner. If bubbles form in the product, this leads to a number of negative consequences:

The rate of heat removal from the heated parts of the engine drops several times, and the viscosity of the oil changes. As a result, it does not enter the smallest openings of the engine, and its lubrication is impaired.
Engine parts overheat quickly.
Due to the deterioration of lubrication, friction between engine parts increases, which leads to their rapid wear. In severe cases, water hammer is also possible.

There are several reasons why the product foams:

The tightness of the cooling system is broken.
During the replacement, the used oil was not completely drained, and a new one was poured in its place, which turned out to be incompatible with the remnants of the "working out".
Somewhere there is condensation.

Now more about each of these reasons.

Leakage

If the tightness of the cooling system is broken, the antifreeze begins to mix with the engine oil, which leads to the formation of foam. Most often this is due to damage to the gasket under the cylinder block cover. Also, antifreeze can get into the oil through cracks that have arisen on body parts due to their prolonged overheating or due to metal fatigue. If an antifreeze leak is suspected, look for smoke coming out of the exhaust pipe. As a rule, it is white. To make a "final diagnosis", you need to let the engine run for 10-15 minutes, and then cover the exhaust pipe with a clean sheet of paper for 20 seconds. After getting wet, the paper must be dried. If after that no even light stains from oil or gasoline are visible on dry paper, then there is a depressurization of the cooling system. There is only one way out: a trip to a car service. Searching for a leak on your own is a long and thankless task.

Incompatibility

Foam appears when the oil being poured according to the synthesis method differs from what was previously in the engine. This usually happens when the mineral mixes with the leftovers of the synthetic. The fact is that the structure of mineral oils is far from ideal, since the range of molecular sizes in such oils is very large. So, in terms of properties, mineral oils are often inferior to synthetic ones, which are obtained during catalytic synthesis and consist of molecules of approximately the same size. When two types of lubricants are mixed, sediment inevitably occurs. As soon as it begins to circulate in the engine, air bubbles appear, i.e. foam. There is only one way to deal with this: always use the same type of oil.

Condensate

If water somehow got into the engine, it will not be able to dissolve in the oil: the chemical properties of these liquids are different. As a result, an emulsion is formed in the engine, which looks like foam. In most cases, this "foam" is not a sign of a malfunction in the engine and does not indicate poor quality engine oil. Usually, the emulsion appears in winter, when the car is poorly warmed up and the moisture that has settled on engine parts has not yet completely evaporated. The solution is simple: thoroughly warm up the car engine before each ride.

Thickening: how it affects engine performance and what to do if it is detected

The most dangerous problem, the cause of which is still not exactly established. The consistency of thick oil may resemble condensed milk, slowly draining from the test probe, or it may look like grease or even plasticine! But the negative consequences of oil thickening are very well known to motorists.

The engine is difficult to start, it does not respond well to pressing the gas pedal, all this is accompanied by the burning of the oil pressure indicator on the dashboard.
At the maximum thickening of the oil, the connecting rods in the engine break away from the pistons and pierce the walls of the cylinder block through and through, which completely disables the unit.

There are several assumptions as to why the oil in the engine suddenly turns into a substance resembling grease.

The ingress of coolant or water into the oil, or the so-called Shell effect (experts from this particular company discovered it in the early 40s). Then, in several samples of thickened oil, traces of water and antifreeze were indeed found. It should also be noted here that not every oil is capable of decomposing and thickening in such conditions, nevertheless, the ingress of antifreeze and water is one of the possible causes of oil thickening, and should not be discounted.
The second reason: bad gasoline. Theoretically, the products of incomplete combustion of such gasoline can react with engine oil additives, which leads to its decomposition (this is the reason car service workers voice when they do not want to service the car under warranty and try to force the car owner to pay for repairs out of his own pocket).

Here it should immediately be noted that the second reason for the thickening of the oil seems to be very doubtful. Bad gasoline is unlikely to greatly affect the lubricating fluid: it enters the engine crankcase too little compared to the volume of oil located there, and it stays there for a very short time, since the temperature at which gasoline evaporates is much lower than the evaporation temperature of the oil from the sump. In addition, if the fuel is mixed with oil, the viscosity of the latter almost always decreases, and here the opposite picture is observed: the oil becomes viscous and thick, like grease. And finally, not only gasoline, but also diesel engines fail from such condensation.

The third reason is the human factor. In any car service, customers are told that only branded oil is poured into their cars. The problem is that this is not always the case. People are different, both good and not so good. In the latter case, no one can say for sure what exactly this “mechanic” poured into the car, and whether it is even possible to call oil what he poured into it.

Causes of Oil Viscosity Loss and Troubleshooting

The oil in the engine can not only thicken, it can also lose its original viscosity. And this phenomenon also has its reasons.

Liquefaction due to thermal cracking. During the cracking process, the components and fractions of the oil decompose into small components. The viscosity of these components is lower. And most importantly, they have a lower boiling point, and therefore, they evaporate better and are more difficult to ignite.
Loss of viscosity due to contaminants in the oil with the fuel.
Viscosity loss due to mixing of oil with solvents, which are often used as detergents for engine flushes and which are almost impossible to drain completely.
Mixing with less viscous oil. At some point, the car owner decided to switch to new oil without completely draining the old one. As a result, even high-quality branded oil can lose viscosity.

There is only one way to deal with all these phenomena: completely drain the used oil from the engine and replace it with a new one. It is not so easy to do this in a garage, because it is not enough just to unscrew the oil drain plugs and substitute an empty bucket under them. The car will either have to be put on a slope, or jacked up at the right angles and wait a long time until the remnants of mining merge (the procedure depends on the brand of the car). So the easiest way to do this is at a car service, where they will not only quickly change the oil, but also check its viscosity after replacement.

There are far more questions than answers when it comes to engine oil, especially when it comes to thickening the oil. Recently, a new theory has appeared: the oil thickens due to the fact that oxidation processes are sharply accelerated in it. And the contaminants present in the fuel act only as a catalyst for these processes. However, this theory, despite all its plausibility, has not yet been tested by anyone.

Under the influence of various factors, engine oil can turn black, thicken or foam. Ways to solve the problem depend on the cause and nature of changes in the structure of matter in the engine.

What are the main properties of engine oil

To improve the performance properties of engine oil, manufacturers use a range of additives that allow:

reduce friction of engine elements;
change the working properties of the oil at different temperatures;
regulate the "alkaline number" of the substance, etc.

The alkali in the composition is responsible for neutralizing acids that enter the power unit system during operation, and also cleans the surface of engine elements from carbon deposits and prevents the formation of deposits. At the same time, particles of contaminants are reliably “bonded” and do not interfere with the normal lubrication of engine parts.

The oil level and its condition should be checked by regularly analyzing the color and consistency of the substance on the dipstick. Darkening is not a cause for concern, but changes in viscosity and foaming indicate problems that need to be addressed promptly.

Causes of blackening: problem number 1

If low-alkaline oil is used, soot settles on engine parts, which increases friction, violates the temperature regime of operation and, as a result, leads to rapid wear of the unit, destruction of engine elements due to local overheating. A similar process occurs if a highly alkaline substance is not changed for a long time - the high content of suspended matter and the aging of the alkaline additive reduces the advantages of such an oil to zero.

If the oil in the engine of your car remains transparent for a long time, this means that it does not cope with its functions - it does not clean the unit from soot and other wear products, it does not protect the metal surfaces of parts from acid deposits that cause corrosion. It should be replaced with a highly alkaline one.

Darkening of the engine oil will occur quickly if the condition of the engine is not the best - a substance with a high alkali content will “eat off” the accumulated dirt. The blackened substance does not need to be changed immediately, it is able to work for the entire prescribed period, providing high-quality lubrication and protection of the motor. The replacement interval for high-alkaline oil is 5000-7500 km in the Russian climate.

blackened oil

The popular opinion "dark means bad" is a relic of the times when cheap motor oil turned black very quickly due to its poor quality and required replacement at a range of 500-1000 km.

Today, the rapid darkening of the substance indicates engine contamination or the low quality of the fuel used. To fix the first problem, you need to flush the engine, to eliminate the second, change the place of refueling.

Foams on diesel or petrol engine

When saturated with air bubbles, engine oil loses its performance, therefore, having discovered foaming, it is necessary to quickly identify the cause and eliminate the problem. When foam is formed:

the viscosity coefficient of the substance changes;
the substance hardly penetrates into the washing channels with a small cross section;
the efficiency of heat energy removal decreases;
motor body parts are poorly cooled;
increased friction of parts during engine operation.

As a result, the moving parts of the internal combustion engine wear out quickly, the motor can fail due to overheating, and there is a danger of water hammer.

Reasons for foaming:

violation of the tightness of the cooling system;
incompatibility of the new oil with the remnants of the old, not drained from the engine;
formation of condensate in the system.

Foaming when hit with antifreeze

Depressurization

Engine oil foams when antifreeze from the cooling system gets into it. Coolant leakage occurs due to the destruction of the protective gasket on the cylinder head, where the antifreeze flows. Foam is also formed when oil is mixed with antifreeze, drooping through cracks in body parts.

An antifreeze leak is indicated from the exhaust pipe when the engine is running. To make sure that the problem is correctly diagnosed, it is enough to start the engine and warm up the car for 7-10 minutes, and then briefly cover the exhaust pipe with a white sheet of paper. Wet paper is dried and inspected - the absence of stains from oil and fuel mixture indicates a depressurization of the cooling system.

Note! Finding a leak and fixing the problem on your own is extremely difficult. Urgent complex diagnostics in the conditions of car service is necessary.

Incompatibility in engine oils

The conflict arises when mixing compositions that fundamentally differ in the method of manufacture and structure. Motor oils are divided into three types:

Mineral. They are obtained by refining petroleum products. The structure of a substance is heterogeneous, it consists of molecules of various sizes. Mineral oil is inferior to synthetic oil in terms of lubricity, viscosity index, and freezing point.
Synthetic. Catalytic synthesis makes it possible to obtain a substance with an ordered structure, consisting of identical molecules and free from impurities. This provides high performance properties of "synthetics".
Semi-synthetic. Combine the best qualities of each of the above.

When buying a used car, do not forget to check with the owner what kind of oil was poured into the engine

Mixing mineral and synthetic oils is unacceptable, since the resulting substance is characterized by uneven density. Such a procedure can thicken the composition and lead to sedimentation, and the circulation of sediment during engine operation causes the substance to foam.

To solve the problem, it is necessary to flush the engine with special flushing oil, fill it with a composition of the type that the automaker recommends, and in the future use only it.

What to do if condensation forms

In the off-season and in winter, condensation can form in a poorly warmed-up engine. Water and oil are liquids that do not dissolve in each other, but form an emulsion when mixed. Therefore, the ingress of condensate into the engine oil entails the formation of foam. Often in color, such a substance resembles condensed milk.

This problem is not related to a malfunction in the power unit or the poor quality of the filled substance. To avoid foaming, before traveling in the cold season, you should warm up the engine well, this will allow moisture to completely evaporate from the surfaces of the parts.

Thickening: why the composition has thickened and what it threatens

For normal operation of the engine, the oil must remain fluid and easily penetrate into the channels for lubrication and cooling of parts. The optimal mode of operation of the motor is to travel long distances with a small load.

If the car is used for short trips with frequent stops and accelerations, is operated in the cold season without a long warm-up of the engine, a thick deposit forms in the engine oil due to the ingress of water and fuel that have not had time to evaporate.

The thickening of the substance is also facilitated by the smallest particles of dust that the air filter cannot hold, by-products of combustion. Another reason for the increase in the density of the substance is its accelerated oxidation when driving in hot weather or with high loads (towing, steep climbs in mountainous areas, etc.).

More frequent oil and filter changes than normal conditions will help to avoid thickening. Car owners who drive short distances and with frequent stops are advised to follow the car manufacturer's instructions for "difficult conditions", i.e., change the filter and oil every 6-8 thousand kilometers or every six months. If the substance thickens in winter, it is better to choose a composition of the same type, but with additives that lower the freezing point.

The consequences of untimely replacement: how thick oil affects the engine (video)

Viscosity reduction: do I need to change

Oil dilution is also a serious problem, which results in a deterioration in its performance. The reasons for the loss of viscosity include:

thermal cracking - the components that make up the oil decompose into components with a lower viscosity and a lower boiling point;
pollution with substances that got along with the fuel;
mixing with solvents remaining after washing the power unit;
mixing with engine oil having a lower viscosity.

To solve the problem, you need to change the oil. It is important to completely drain all the substance from the system by lifting the car with a jack at the right angle. It is faster and better to carry out the procedure in a car service, where specialists will check the viscosity of the new substance after pouring.

Curled up inside the motor

In some cases, the oil does not just thicken, but coagulates, forming a substance with the consistency of grease or even plasticine. A strong condensation of a substance is very dangerous because:

the engine starts with difficulty, does not respond well enough to gas, while the oil pressure indicator lights up continuously;
there is a risk of separation of the connecting rods from the pistons, as a result of which they can pierce the walls of the cylinder block, completely disabling the power unit.

Thickened and coagulated matter

An unequivocal reason for this thickening has not been found. There are several assumptions:

the ingress of water and antifreeze into oils with certain technical characteristics (Shell effect, discovered in the 40s);
low quality gasoline, the presence of foreign chemicals in it (but this version is very controversial, since thickening is also observed in diesel units);
human factor - filling in a car service (or independent purchase) instead of high-quality engine oil of an unknown substance of dubious origin.

Having found signs of curtailment, it is urgent to change the oil by thoroughly flushing the system.

In order for the engine to work properly for the entire period specified by the manufacturer, it is important to monitor the condition of the engine oil and regularly update it in accordance with the mode of operation of the car, warm up the car well on cold days and use high-quality fuel.