If the oil darkens , it means something is wrong, some car owners think. But is this really so? After all, it’s one thing when it quickly turns black after replacement (still almost fresh), and another thing if after a couple of thousand kilometers.
There are several reasons why this happened - poor-quality lubricated fluid, dirty condition of the engine, long mileage of the car without replacement, switching to higher quality oil, overheating, even due to bad fuel. How do you know when engine oil quickly darkens is good and when it’s bad? After all, this is not always a negative consequence and you need to worry. Then be sure to pay attention to additional factors and check the quality of the oil.
Gradual aging and darkening is a natural process . Therefore, the main task of the car enthusiast is to figure out whether the darkening is caused by positive or negative factors.
It's not just engine parts that wear out
During the operation of a car, gradual wear of its components, especially the engine, occurs, and no matter how much we would like to prevent this, we cannot succeed. In this case, not only components and mechanisms are subject to wear, but also the working fluids poured into it.
Therefore, the list of engine maintenance work includes the replacement of technical fluids. It is especially important to change engine oil on time.
All automobile manufacturers indicate in their technical documentation what frequency should be between changing a given working fluid. But many motorists are accustomed to independently determining whether they can continue operating the engine with oil filled or whether it is time to replace it.
And they do this based on the color of the liquid - if the oil has become very dark, then it’s time to buy a new one and replace it.
Next, we will try to figure out whether the darkening of the oil is really a signal that it is time to go to the store for a new one, crawl under the car, or leave the replacement operation to specialists at a service station.
Why does engine oil turn black?
Let us immediately note that in any case, during operation, the oil will turn black, but this can happen for various reasons. First, let's look at the lubricant itself.
Modern oil for an internal combustion engine is a multicomponent liquid that must perform a number of important functions inside the engine.
The first is the creation of an oil film between surfaces to reduce friction between them. This film is formed during the process of lubrication of these surfaces.
The second function is to remove heat from the rubbing elements. While the engine is running, its components still rub, causing them to heat up. And if the heat is not removed, then due to excessive temperature the metal will begin to expand, which leads to jamming of the assembly.
And the third function is washing surfaces to remove wear products and dirt. All due to the same friction, small metal shavings are formed, which later act as an abrasive, increasing the wear of surfaces and the engine as a whole.
Dirt also acts in the same way. Gases escaping from the cylinders into the crankcase also carry polluting elements such as soot - and it is not desirable for them to settle on working surfaces.
And if metal shavings and dirt often settle to the bottom of the crankcase after flushing or are retained in the filter, then the oil dissolves the soot and retains it. For this purpose, it contains alkaline detergent additives.
Alkali is a universal solvent and acid neutralizer, and its presence in the lubricant prevents soot and other contaminants from settling on the surfaces of components. And since they do not settle anywhere, but linger in the oil, they will ultimately lead to a change in the color of the oil - its darkening.
How quickly should the grease turn black?
Many people wonder what color the oil should be at different mileage.
It is impossible to say unequivocally that with such and such a mileage its color should be this color, and with more mileage it should not change more, since this depends on several factors:
- lubricant quality;
- its additive package;
- technical serviceability of the power plant;
- the degree of wear and contamination.
Let's assume that the engine is new and technically fully functional, and the change in color depends entirely on the oil and its composition.
When using high-quality oil, its darkening will not occur earlier than after several thousand kilometers and this process will be gradual.
But here too there are many nuances.
Motor oil may contain different amounts of detergent alkaline additives.
So, in a lubricant with a low alkali content, the flushing process will be slow, and, therefore, the oil will turn black later.
Conversely, with a large amount of alkaline additives, the removal of pollutants will be more intense, and the material will darken earlier.
But in any case, the oil will darken and this is not a sign that it is time to change it, unless, of course, its service life has been exhausted. This is rather a signal that the material is of high quality and performs its functions.
But the lack of darkening after long-term use is not a good sign - the oil does not flush, and dirt settles on the surfaces. In this case, it is better to replace it with another type of working fluid.
It is worth noting that you should not use the lubricant for longer than that specified by the car manufacturer.
The fact is that the oil uses up its additives as it operates and eventually ceases to perform its functions, including flushing.
As a lubricant ages, it will be less able to remove contaminants from surfaces. These, in turn, will begin to affect heat transfer and friction.
By settling on the walls of the oil channels, dirt and soot will reduce their diameter and throughput. If you do not replace the lubricant in a timely manner, this will ultimately lead to coking - the contaminants on the surface will become so dense that the new lubricant simply will not be able to wash them off, and all this will affect the life of the power plant - major repairs will have to be carried out earlier.
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Comments 33
I agree with many! It gets dark quickly with a diesel engine. And the USR has a huge impact. I hadn’t removed the Egr yet, but by the time I changed it the oil became not only black, but also thick. Some kind of shoe polish. Now the viscosity remains the same throughout the entire operating interval, but it darkens faster than that of gasoline.
really calm yourself down! Read about the oil drop test! especially useful for diesel engines!
and it will be clear WITHOUT DOUBT that something is wrong with your oil!
“OIL DROP TEST” Googled.
For diesel, black oil is normal. How quickly it turns black depends on the quality of the oil (more precisely, its detergent properties), what kind of diesel fuel you drive and how the EGR valve works.
I also have black after 10 minutes after replacement
of course it’s normal - it’s a diesel... for me it’s black after almost the first trip...
Relax, everything is fine. It would be worse if it didn't get dark anymore. =)))
EVERYTHING IS CORRECT, NO REASON FOR WORRY!
I have a diesel engine in Luaz, I fill it with fresh oil and after 2-3 MINUTES of work it’s hard to tell the difference between tar and tar. The engine has been running without problems for 8 years. This is a diesel. I forgot, TOTAL 10w40 oil
You should write down at least some brand of oil, viscosity parameters. I don’t know who it is, but my 5W-40 ENEOS oil turned black (that is, it became really black) after 4-5 thousand kilometers of mileage, and the dipstick was grayish-transparent. The EGR is muted.
Norm. My oil was black immediately after changing it. Although in my presence they all drained it. It’s just that some amount of it remained on the engine parts and when new oil was poured in, it washed away the remnants of the old one and mixed with it. Really black, you can easily think that the oil has not been changed at all. Hence, probably, the legends that the oil was not changed during maintenance.
For a diesel engine, rapid darkening of the oil is normal, because the EGR throws soot from the exhaust back to the intake and ultimately it falls into the oil. it becomes light only immediately after replacement, and then not for long
Blackening of oil is a normal cumulative phenomenon! consists of gases penetrating through the rings and combustion at shear speeds (piston-cylinder and other parts of mechanisms). the oil can be light in not so much time, for me it’s a week. if the gases did not penetrate into the interior of the internal combustion engine, the crankcase ventilation system was not installed on the internal combustion engine, and since this system is still not excluded on this type of engine, then everything is fine!
Therefore, about detergent oils - this is the usual advertising nonsense!
Normal for a diesel. Change synthetics every 8,000-10,000 km and you will live happily ever after.
You have a car, as I understand from the showroom... did you hear that thread about running in the engine? So not only is it a diesel. So, during break-in, the oil may change color from our diesel fuel.
and according to the stories of one friend. I don’t know how it is with you, but with us... unless you were present when the oil was changed and you personally didn’t see it being poured there in front of you. at the first change they might throw it away... when the car comes off the assembly line during break-in, it undergoes an intermediate oil change, so to speak, for a reason... and at the service station they think that you can cheat ;), some people don’t change the oil themselves after break-in, like the car is not removed from the warranty and why waste money - but in vain... in a car there is a valve in the filter and if the pressure there is higher than normal (for example, the filter is clogged or the oil has become thicker in the cold), the valve opens and the oil rushes past the filter... this is not guuuddd... if you had it changed “formally” during such a replacement, then not surprising, although after 8,000 km during running-in it could even become like half-boiled condensed milk
Effect of motor malfunction on lubricant color change
We only looked at the oil, and found that the latter will darken as we work. The condition of the engine also affects the color change of the lubricant.
Wear of the cylinder-piston group will lead to a significant increase in the amount of gases escaping from the cylinders, which will cause a faster change in the color of the engine oil.
If the power system in a gasoline engine is misregulated, the darkening will occur even faster.
For example, due to incorrect adjustment, an enriched combustible mixture is supplied to the cylinders. Due to the large amount of fuel, this mixture will not be able to fully burn in the cylinders, which will result in the formation of soot that settles on the cylinder walls.
The oil, washing the walls, will wash away this soot and keep it in itself, while quickly darkening.
In diesel engines, the lubricant will change color much faster than in a gasoline engine, even if the engine is fully operational. The reason for this is the peculiarity of the fuel system and the fuel used in these engines.
Diesel fuel produces significantly more soot during combustion. Some of it will enter the crankcase along with the escaped gases. Because of this, the oil in diesel engines turns black faster.
As a short summary, we note the main reasons on which the rate of darkening of the oil depends:
- The amount of detergent additives in the composition of the lubricant (With a small amount of these additives, the darkening will occur gradually, since the alkali will not wash away contaminants intensively, but a large number of cleaning components in the lubricant will ensure faster washing and removal of dirt, but because of this the oil will be faster will darken);
- Cleanliness of the engine (A lot also depends on this. For example, the engine used low-quality oil, which did not wash away dirt well, and a large amount of it settled on the surfaces inside. Then the oil was replaced with a high-quality one, with a good additive package. Detergent components of the new lubricant will begin to actively remove dirt, causing the oil to quickly turn black);
- Technical serviceability of the engine and the degree of its wear (A serviceable and unworn engine will have a gradual darkening of the lubricant. A worn-out unit, in which the operation of the power supply, ignition or gas distribution system is disrupted, will very quickly cause a change in the color of the lubricant).
At the same time, we also found out that darkening of the oil is a natural process, and you shouldn’t be afraid of this, especially since this is a good indicator if the color change occurs gradually and you can continue to drive the car calmly.
It is much worse if the lubricant does not change its color; this can have a negative impact in the future, since dirt can clog the channels, leading to oil starvation of components and mechanisms. As a result, the engine may seize.
If the oil turns black after just a few tens of kilometers, then this is something to think about. This can happen after changing the brand of lubricant.
For example, at first a low-quality fluid was used, which is why large amounts of pollutants accumulated inside the engine. After filling in a good lubricant, it began to actively wash away the dirt.
In this case, you can do differently - use an engine flush or continue to use the filled oil, but significantly reducing the mileage until the next replacement, for example, not 10 thousand km, but 5 thousand.
In this case, it is advisable to periodically change the oil filter. This will slightly reduce the amount of dirt in the oil.
The second option in case of rapid darkening is severe wear of the engine and the need for major repairs or improper operation of its systems.
To understand the reason for the rapid blackening of the lubricant, first of all, it is necessary to check the performance of the engine systems, and also measure the compression, which will make it possible to understand why the lubricant quickly changes color - from malfunction and wear of the engine, or from the oil itself.
Ways to solve the problem
If your engine's black oil becomes too thick or darkens too early, you need to find the cause. There can be several ways:
- The engine needs to be flushed because it is excessively contaminated with various particles and old oil that could adhere to the walls of individual parts.
- Check the engine crankcase: gases may accumulate in it. In this case, the problem is in the exhaust system.
- Replace the oil with another fluid of more suitable viscosity, change the manufacturer, carefully study the alkaline balance of the product.
- Check and clean the oil channels in particularly difficult cases, if poor quality fluid has clogged them too. If this is not done, there is a threat to the operation of the engine and cylinders. The oil filter also needs to be changed; in this case, it won’t hurt to change it several more times during the operation of the new fluid, since particularly large particles and viscous substances left over from the old one can settle in them.
- It is not recommended to use aggressive detergents.
- Chemical components that are highly aggressive may remain inside the system. This is another reason why the liquid quickly turns black.
If flushing fluid was used, it is better to fill in thicker oil, since it will also partially remain in the system; its viscosity is low, which does not fit well with such components. If this is not done, the internal combustion engine will experience increased loads. To solve the problem, it is recommended to change the oil more often.
- The oil can turn black if exhaust gases enter the crankcase, its consumption will also increase, and fuel consumption will also increase. This problem can cause serious consequences and costly repairs, for example, the cylinder block may need to be replaced. In order to solve the problem, you can try to bore the cylinders and replace the rings. Most often, this problem occurs if the car is not new and has a good mileage.
- If low-quality oil was poured in, then after flushing the system and replacing it, the problem will gradually be solved, but you will have to replace the filters and the fluid itself several times. If you use a fluid with a high alkali content, you need to change it every 5-7 thousand kilometers.
