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Why does engine oil turn black quickly? Selection of oil for the car. Terms of oil change in the car engine
Why does engine oil turn black quickly? Selection of oil for the car. Terms of oil change in the car engine

Why does engine oil turn black quickly? This question worries many motorists. There are many answers to it. Let's consider them in our article in more detail. We will also pay special attention to the most common types of additives used to improve oil performance.

Natural cause of blackening

Almost every driver wonders why the oil in the engine turns black. The reasons for this phenomenon are different. It should be noted that changing the color of the oil during its operation is a natural process. Darkening is due to the fact that one of the fundamental functions of the liquid in question is to clean the engine of harmful components that appear as a result of the operation of the motor and cause significant harm to it.

The process of performing the engine cleaning function consists in collecting harmful elements from the cylinder walls, from the pistons, as well as rings and other engine elements. Purified particles are retained in the oil composition throughout the entire period of operation.engine. This results in a natural darkening of the liquid.

Why engine oil turns black quickly
Why engine oil turns black quickly

For what period is color change allowed

When is the darkening of the oil in the engine considered a normal process? Experts in the field of car operation assure that its planned replacement should be carried out after every 2-3 thousand kilometers (depending on the quality of the product). It is after passing the specified distance that blackening is a normal phenomenon. If this happens much faster, then the motorist should pay attention to the he alth of the internal structure of the car, for which it is recommended to contact the specialists at the service station.

A motorist who owns a car that runs on diesel fuel should take into account that this type of fuel clogs the engine much more, as a result of which the product becomes contaminated much faster. After how many kilometers do they change the oil in the engine in this case? Most of the recommendations of experts say that it is desirable to evaluate the contamination of the product every 1000 km.

Let's look at the most common reasons why engine oil quickly turns black.

Using a better product

If during a certain period a motorist poured a low-quality product into the crankcase, but then replaced it with a good one, it starts to darken very quickly. This phenomenon is due to the fact that the detergent additives contained in the composition of a higher quality product process the enginethe inside is much better than the ones that are in the cheap. Accordingly, good oil has a much more effective effect on the motor. It will begin to quickly remove not only planned pollution, but also old deposits that were not removed by the previous product.

If the cleaning procedure is performed correctly, the used oil has a slightly viscous consistency and a uniformly dirty appearance. In this situation, experts recommend replacing the product ahead of schedule.

Darkening after repair

What should I pay attention to if the engine oil turns black? The reason for this phenomenon may be a recent major overhaul of the vehicle. In such a situation, excessive and rapid darkening of the composition may be due to the fact that it cleans the motor from metal chips formed as a result of restoration work, as well as during the interaction of rubbing pairs.

Automotive service professionals strongly recommend that after an engine repair, change the oil earlier than planned, due to the presence of a large number of blockages in the engine.

Selection of oil by car
Selection of oil by car

Wrong ratio of ash and TBN in the product

Practice shows that with an increased ash content and a low level of TBN, premature blackening also occurs in the oil composition. You can find out what indicators this or that product has by examining its components indicated on the packaging of the product. So the highersulfate ash content, the more pronounced will be the cleaning ability of the product. Consequently, the blackening of the product during engine operation will occur much faster. Accordingly, the lower this indicator, the cleaner the oil will be after the end of its use. However, you should not rejoice, as this indicates a low quality of products.

It should be noted that in terms of the ratio of ash content and TBN, the oil must be selected based on recommendations for a particular model and brand of car.

As for the level of TBN, its low indicator indicates the need to replace the product every 6-7 thousand kilometers. It should also be noted that oils of this type are very sensitive to fuel quality, at low rates of which their useful properties are largely lost.

Image"Liquid moth" oil additive
Image"Liquid moth" oil additive

Purchasing a fake

Why does engine oil turn black quickly? One of the most common causes of such a problem is the acquisition of a fake. Unfortunately, all motorists can face such a problem.

To avoid such a nuisance, you should know a certain list of distinctive features of a branded product, thanks to which you can avoid buying a fake.

If, by the will of fate, I had to deal with a poor-quality tool, the motorist needs to urgently replace it with the original one. It is advisable to flush the engine before this. The urgency of changing the oil to a more expensive onedue to the fact that a cheap product has very low performance characteristics. Of course, they do nothing to improve engine performance.

Ingress of combustion products

Even the best engine oil will turn black quickly if it gets contaminated with combustion products. This is due to the rapid oxidation process. It should be noted that color change is far from the only negative point that occurs during the oxidation process. The main thing is that the oil begins to lose its useful properties, which is especially harmful to the motor.

The main cause of such a problem is depressurization, which can be caused by damage to the oil scraper rings or, for example, a violation of the integrity of the gasket located at the cylinder heads. The cause of discoloration is often the ingress of gasoline into it. If it burns with the fuel, it will also turn black prematurely.

How can you determine that the blackening of the oil occurred precisely because of the ingress of fuel into it? This is done quite easily if we compare the rate of combustion of the product. If the oil disappears quickly enough and at the same time turns black, then the cause of this phenomenon is precisely the seepage of fuel into it.

Crankcase gases getting into the engine

This cause of discoloration can be encountered if there is a malfunction in the ventilation system. In this case, crankcase gases have the ability to penetrate into the oil and actively contact the lubricating elements. It should be noted that the consequence of this is a fairly rapidchange in color of the fluid in the crankcase. Moreover, in this case, the oil suddenly loses its performance, which negatively affects the operation of the engine. The speed of such a process is directly proportional to the volume of gases entering the engine.

Fuel additives
Fuel additives

Poor quality fuel

A fairly common cause of oil discoloration is the use of low-quality fuel by a motorist. It should be noted that clean fuel does not contain excess impurities, due to which a smaller volume of combustion products is released, and the oil turns black rather slowly.

To avoid this problem, engine service professionals strongly recommend using only high quality fuel. Thanks to this, the motor will be protected from wear.


Why does engine oil turn black quickly? As practice shows, a fairly common cause of this problem is overheating of the engine, constantly working in difficult conditions. In this situation, the temperature of the oil will also rise, as a result of which it will begin to "burn" and change its color dramatically.

When the engine is running under such conditions, the time for changing the oil in the car engine is significantly reduced. Otherwise, it will turn into a very viscous mass that will resemble fuel oil. This leads to very sad consequences, up to a complete replacement of the engine.

Terms of oil change in the car engine
Terms of oil change in the car engine

No blackening

Some motorists are surprised that the oil contained in the crankcase does not darken at all even after passing the prescribed 3000 km, or only slightly changes its color. The only reason for this is the lack of cleaning properties of the product. In this situation, you should immediately replace the previous product with a better one from a trusted manufacturer.

Car oil "Mobile"
Car oil "Mobile"

How to choose

With the right selection of oil for a car, you can significantly save not only time, but also money that can be spent on engine repairs. How to choose the right product by vehicle type?

When choosing a tool, be sure to pay attention to the tolerance specified in the documentation for the vehicle. It is also worth paying attention to the viscosity of the product, indicated in the international SAE format. It is on this indicator that the fluidity of the oil and the ability of the engine to start quickly in the cold season depend.

Special attention should be paid to the season in which the use of the product is planned. So, a product intended for use in the cold season is marked W. Near this letter there is an indicator represented by numbers. The lower the value, the lower the temperature the oil can withstand. If the use of the product is planned for a hot period, then in this case it is worth giving preference to a brand with increased viscosity.

When choosing oil for a car, you should pay attention to what recommendations the manufacturer gives on this matter. So,for Toyota and BMW vehicles, it is recommended to use only original and high quality products. Mixing different species is contraindicated.

Recently, a particularly common product is Mobil motor oil, which is ideally compatible with many makes and models of cars. For example, ESP Formula is excellent for use in diesel engines, and the Advanced Fuel Economy action is aimed at saving fuel consumption, which is why it is often used by owners of cars of the latest models. As for the Product Specifically Designed for Vehicles 150,000 + km, it is recommended to be used for those engines with more than 150,000 km.

About additives

To improve the quality of the engine and reduce the amount of combustion products emitted, a motorist can use a variety of fuel additives that are designed to purify it. The best products of this type include:

  • RVS Master.
  • "Octane Plus".
  • Castrol TBE.
  • "Suprotek SGA".
  • Wynn's Supremium.

All of the listed fuel additives not only have the property of cleaning it, but also increase its octane value. In addition, they help increase engine power.

Engine blockage
Engine blockage

The "Liqui Moli" oil additive is of high quality. This product allows not only to increase the level of the cleaning function of the product, but also to improve engine performance, as well as technical characteristicssome vehicle nodes. Liquid Moli oil additive contains a viscosity stabilizer, which allows you to adjust the degree of product liquid depending on weather conditions.

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