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.
When is dark oil normal?
Draining the Engine Oil
Black oil is not a cause for concern if it has been stained within the specified oil change interval. Those. if the working fluid has served 5-10 thousand kilometers and has retained its consumer properties, while at the same time acquiring a dark tint, then there is no need to worry: this is a typical indicator for a good oil. Why? It’s simple: any chemical base of a technical fluid includes alkali. It allows you to clean the surfaces of all working units from carbon deposits and contaminants, preventing them from coking. In other words, it separates deposits harmful to the engine and removes them from the power plant. As a result, contaminant particles mix with the engine oil, causing it to darken.
A change in color of the fluid inside the car's engine indicates that all waste compounds are being held within the circulating engine oil. Moreover, they do not get on the parts of the working area. This ability of the protective layer minimizes the risks of the formation of oxidation reactions inside the installation and increases the service life of the internal combustion engine. When carrying out routine maintenance of the vehicle and replacing the lubricant, all the harmful substances washed out by it are merged with it, without settling on the surfaces of the engine.
Turns black – it means it’s working
The automobile oil system is a closed circuit. From the crankcase, the oil pump drives lubricating fluid through the system channels. Making a full revolution, the engine oil picks up carbon deposits and oxides and returns to the crankcase. That is, the product constantly circulates through the dirtiest “nooks and crannies” of the internal combustion engine (ICE). It is quite natural that over time the grease turns black.
At the same time, we should not forget about the temperature regime in which the oil is located. Its temperature often reaches more than 100°C. High heating promotes effective lubrication of components and thorough removal of carbon deposits - this is another reason for darkening. This color change is called "oil work". From this we can conclude that if after a long run the oil has not darkened, it is experiencing a deficiency of cleaning additives. Naturally, all oxides, carbon deposits and other slags remain inside the engine, settling on its components. In this case, all you have to do is exclude the low-quality product from your purchases.
Engine oil turns black quickly: possible reasons
If you only managed to drive a few hundred kilometers on fresh oil, it is inappropriate to talk about the norm here: there is a problem. And at this stage, it is important to recognize what exactly caused the fluid to quickly become obsolete - the oil itself or the car engine.
Poor quality of protective lubricant is the most common situation. The working film cannot provide the engine with the proper level of protection from constant temperature changes. As a result, there is an aggressive interaction of power mechanisms, their wear at lightning speed and the formation of a large amount of soot from the burning liquid. It is dangerous to operate the engine on such a mixture for a long time - repairing a jammed system is by no means a cheap “pleasure”.
Checking the oil level
There are also cases when motor lubricant becomes similar to fuel oil in consistency and color. Here the fuel and lubricants are no longer just darkened, but turning black at an incredibly high speed and acquiring excessive density. This indicator indicates that an active combustion process of the oil base is taking place inside the installation. This situation occurs when significant wear of the cylinder-piston group is observed. Black oil in the engine is formed due to a violation of the cylinder seals and a large amount of unburned fuel entering the working area. The fuel, in turn, mixes with the oil, changes its chemical composition and makes the mixture unsuitable for further use.
If the oil turns black, the following consequences occur:
- reduction in engine power performance,
- increased consumption of the fuel mixture,
- complete stop of the engine due to the destruction of the main working units.
If you have figured out why the engine oil turns black, and the reason for this is poor-quality products or problems with the system, you must immediately take measures to correct the problem. In the first case, it is enough to replace low-quality products. Here you can rely on reviews from car owners and recommendations from specialists.
The main thing is that the technical fluid must fully comply with the parameters established by the automaker.
Otherwise, the situation may repeat itself with worse consequences. It is also recommended to carefully inspect purchased canisters of liquid for traces of counterfeits. A wide range of motor oils, unfortunately, may largely consist of counterfeit goods. Be carefull.
As for problems with the tightness of the propulsion system, replacing the fluid alone will not help. Replacing a piston group is a complex task that does not tolerate mistakes. And it is advisable to entrust it to qualified service center specialists. After replacing worn elements, you will need to thoroughly flush the engine to remove any remaining burnt oil-fuel mixture.
How to solve a problem
How to prevent oil darkening or get rid of the consequences of this problem? Here are a few main factors why car grease darkens very quickly:
- the engine is so dirty that it can change the color of the lubricant;
- accumulation of gases in the engine crankcase;
- oil saturation with alkaline additives.
With improper care, the contamination of a car engine increases until the oil channels become clogged. This condition is unsafe for the operation of internal combustion engine components and cylinders. Therefore, immediate cleaning and replacement of the oil filter is recommended. It's even better to change the filters several times during the prescribed mileage cycle, which promotes cleaning. It is advisable to carry out standard cleaning without the use of aggressive cleaning agents.
Chemically hard components partially remain inside the oil system - this is why the oil turns black. In addition, flushing oils have a much lower viscosity level, which cannot be considered beneficial when mixing them with newly filled “original” lubricant. As a result, the engine faces increased wear. It is better to reduce the mileage cycles between service oil changes.
The oil turns black due to exhaust gases escaping into the crankcase. At the same time, fuel and lubricant consumption increases sharply. This problem may require major repairs. The problem is partially solved by boring the cylinders and replacing the piston rings. However, such troubles usually occur in old cars with significant engine wear.
During a service run of the engine, it is recommended to change the engine oil, which turns black due to the abundance of alkaline additives, several times along with the filters. After gradual cleaning of the unit, the color of the lubricant returns to normal. However, it should be remembered that operating a car in normal mode requires changing high-alkaline oil every 5–7 thousand km.
If the engine oil quickly becomes dark, do not be alarmed. This means that it does its job - it cleans the engine of deposits. Change the lubricant in a timely manner and buy only the original product.
Why does diesel oil turn black faster?
If in a gasoline engine the lubricant requires replacement after five to ten thousand kilometers, then in a diesel engine this procedure must be carried out more often. Accordingly, the darkening of the oil occurs faster. Why? A diesel engine quickly becomes contaminated with soot particles, and the reason for this lies in the incomplete combustion of the fuel mixture. This situation leads to an abundance of precipitation harmful to mechanisms. Motor oil, circulating in the work area, absorbs unburnt particles, treating previously damaged surfaces with detergent chemical compounds, and promotes the unhindered movement of parts. Because the amount of deposits in the lubricating fluid increases with each press on the gas pedal, and its properties are degraded much faster than in a gasoline unit.
Timely replacement of the engine composition has a beneficial effect on the operation of the entire vehicle.
Consequences of long-term driving on black oil
Blackened oil loses its performance qualities, which increases friction between engine components. The load on the motor increases, causing it to start knocking. In this case, a complex repair of the power unit is required, which is not cheap.
When using black lubricant, fuel consumption increases and the internal combustion engine quickly overheats. A large amount of wear and combustion products accumulate in the power unit, the oil channels become clogged, and the engine fails.
Pure oil is a symptom of poor quality products
Engine oil in the engine
When replacing engine fluid, you may notice that its color has remained unchanged since the moment you changed it during the last maintenance. If, under constant engine overloads, the oil has retained its original appearance, and it has been used for more than one thousand kilometers, it means that liquid with an ineffective set of detergent additives is splashing inside the power structure. As mentioned earlier, normal engine operation is accompanied by darkening of the lubricant. Its crystal purity indicates that the parts are not cleaned of carbon deposits, debris and sludge, which significantly reduces their useful life.
Remember that high-quality motor fluid should turn black during prolonged use; pure lubricant indicates its unsuitability for continuous use.
When faced with such a situation, you should change the selected brand of motor oil. Refilling a previously used product may be the last time for your vehicle's engine compartment.
What can you do?
- To be sure of the quality of the lubricating fluid, it is better to choose products from trusted brands. Surely it will cost more, but remember that the costs of major repairs are more significant.
- Do not neglect the recommendations of the automaker that produced the car. The technical documentation indicates with what characteristics the oil should be poured into the power unit.
- It is better not to change the brand of lubricant without good reason. This may be required only if the flooded one does not cope with its tasks.
- Flush the engine periodically. For this purpose, special compounds are used. Their peculiarity is the increased content of detergent additives. This procedure is required when changing the brand of oil. It allows you to remove dirt and remnants of the old composition.
- Don't neglect regular oil changes. They should be performed in accordance with the manufacturer's instructions. At the same time, you need to change the filters and make the necessary adjustments to the functioning of the systems.
The gradual darkening of engine oil is a natural process that will have little effect on the performance of the internal combustion engine. However, if blackening occurs rapidly and intensely, then it is worth contacting a car service to diagnose and identify the cause. In order not to harm the car’s power unit, you should follow the manufacturer’s recommendations and choose lubricating products from responsible brands.
We diagnose the problem in a timely manner
Comparison of fresh/used/old oil
To understand whether the fuel darkens quickly or, conversely, remains crystal clear, it is necessary to regularly assess its condition using an oil dipstick. The check should be carried out 1-2 times a week in order to promptly recognize the problem.
Please note that before analyzing the color, consistency and level of the lubricant, it is necessary to wipe the dipstick only with a clean cloth. If thread fibers, spools or other debris enter the working area, it will quickly contaminate the technical fluid.
Motor oils for summer and winter use.
In the field of motor oils, a distinction is made between seasonal (used either in summer or winter) and for year-round use.
The appropriate SAE viscosity grade is indicated in a note in the engine compartment.
Wherein:
- The lower the first number (5), the lower the lower temperature limit (low temperature viscosity) at which the oil still has sufficient fluidity. 5 means - can be used down to an external temperature of -30 C.
- The higher the second number (30), the high temperature viscosity. 30 means engine oil can be used up to an external temperature of 30 C.
- W stands for winter. In the case of seasonal oil, the classification is as follows:
- Summer: SAE 30 (up to 30 C).
- Winter: SAE 5W (up to -30 C).
