What to do if the engine consumes a lot of oil. Why does the engine eat oil? Symptoms of increased oil consumption
Everyone knows perfectly well how important it is to change the oil on time. Many motorists who look after their vehicles regularly check the engine oil level. Others believe that it should remain at the same level from replacement to replacement.
Personally, I check the oil level very often, about once a week. A huge number of reasons can provoke “oil gorging”. It is very important to determine what exactly contributed to the problem in order to successfully get rid of it.
Many motorists are sure that even a slight burn of oil indicates the presence of a problem. In fact, this is far from the case. Each modern power unit consumes this technical fluid in a certain volume. You need to understand that an internal combustion engine cannot function without oil, and over time its amount decreases. Yes, every automaker is developing systems that would help reduce these losses to a minimum.
Most of the engine oil is consumed in the piston group of the engine. Due to strong friction, the liquid evaporates, due to which its amount is significantly reduced. If the required amount of fluid is not added in a timely manner, the engine can wear out very quickly, which will lead to negative consequences for its performance. In addition, the piston group is the place where the highest temperatures are reached. As a result, the oil can break down into a film that settles on the valves and piston rings.
Each modern engine has its own standard for oil losses. On average, this is 0.3% of the total gasoline consumption per kilometer driven. Thus, if a car can consume 5 liters of fuel in 100 km, then 10 grams of oil is considered normal. As a result, the car owner will have to add a liter of oil every 10 thousand kilometers. However, this consumption is only applicable when used under normal conditions. In everyday life, oil consumption can be 2-3 liters for the same mileage. This is also the norm for some manufacturers.
Top 5 possible causes of oil burns
If you begin to notice that your car begins to consume a large amount of oil, it is very important to understand the possible reasons. In some cases, the reason for this is the banal low quality of the lubricating fluid. If the problem occurs for the first time, try changing the oil to another one. If such measures do not help, perhaps the reasons are as follows:
- Presence of any punctures or cracks. For this reason, the integrity of the crankshaft, camshaft, and balancing shaft seals should be checked. These components are subject to excessive wear and begin to leak oil over time. In addition, this can happen due to improper repairs. Rubber parts are subject to excessive wear due to overheating of the power unit.
- Leaks from various gaskets, such as valve covers, rear oil seals and many others. A similar problem can be caused by natural wear, breakage of bolts due to external influences, or poor quality of their fastening from the very beginning. In this case, the oil flows very slowly, but over time the speed may increase. You can try to tighten them, but the best solution is to completely replace the worn-out unit. The greatest danger is an oil leak from the cylinder head gasket. In this case, you need to count on expensive repairs.
- Need for major repairs. Over time, the engine and its components wear out completely, causing the oil to go to waste. The oil burns in the engine cylinders, forming a protective film. Soon the engine will not be able to operate fully and will have to undergo significant repairs. In most cases, such a problem can be recognized precisely by excessive oil consumption.
- Engine oil entering the cylinders will cause excessive wear on the intake valve stems. This technical fluid flows into the inlet, after which it is sucked into the cylinders - where it finally burns. A certain part of the engine oil remains on the hot walls of the exhaust tract, which significantly complicates the operation of the power unit. In addition, oil may escape through the catalyst into the exhaust pipe, which can be recognized by thick black smoke. The problem can most often be solved by replacing valve seals and valve bushings.
- Excessive wear of cylinder walls, piston rings or other components of the power unit. Due to constant friction, the gap between the cylinder and the piston increases, which significantly increases the size of the oil film on the cylinders. In total, this leads to a loss of expansion force, due to which the piston rings can no longer perform their functions. This also causes coking of the rings, which eventually leads to their failure.
Which models are most affected by the problem?
Almost all modern cars suffer from the problem of oil burning. However, some people face this problem more, others much less. Many people do not understand why a new car begins to eat oil so much, while others do not check it at all, but rely on the specialists to check it themselves during maintenance. Today, all modern portals claim that cars of the Audi, BMW and Subaru brands are most susceptible to oil burns.
Having studied reviews of more than a million car owners, the portals come to the conclusion that drivers of these three brands, on average, fill in about 1 liter of engine oil for every 1,500-3,000 kilometers driven. The most problematic motors are:
- 2.0- and 3.0-liter turbocharged engines from Audi.
- 4.4- and 4.8-liter twin-turbocharged engines from BMW.
- 2.0-, 2.5- and 3.6-liter six-cylinder engines from Subaru.
Such engines were installed on the following cars:
- Audi – A3, A4, A5, A6, Q5.
- BMW – 5, 6, 7 series, X5.
- Subaru - Outback, Legacy, Forester, Impreza.
Numerous studies show that oil consumption is not related to mileage. These cars begin to eat technical fluid immediately after release. This is a normal phenomenon and does not require additional repairs.
Conclusion
Oil burns are a common problem that almost every car enthusiast has heard about. When the first signs of this phenomenon appear, you should definitely conduct a full technical review of your vehicle. Perhaps the problem is not critical and requires an inexpensive and quick repair.
The main signs by which you can determine that the engine is eating oil:
The oil level on the dipstick “drops” quickly;
Exhaust gases are blue;
Oiling and coking of spark plug electrodes;
Traces of oil in the throttle valve assembly and in the turbine area;
Oil leakage through crankshaft oil seals;
Oil in the expansion tank.
Why does the engine eat up oil?
Increased oil consumption also occurs in cases where the turbine shaft bushings are worn out, low-grade motor oil is filled in, when a crack appears in the cylinder block or cylinder head, oil leaks from under the filter or valve covers, as well as through the crankshaft seals.
And the last thing that directly depends on the car owner is operating the power unit to the limit with an aggressive driving style.
Let's look at the reasons point by point.
If the crankcase ventilation does not work properly, then the gases are poorly cleared of oil particles, which are drawn into the starting manifold, then into the cylinders and burn.
When oil burns out, its level in the engine sump also decreases, which reduces its ability to cool and causes it to heat up even more. If you skip this moment and do not take any measures, the engine will face complex and expensive repairs or replacement.
Oil leak – there is no oil in the exhaust gases:
Wear of the turbine rotor support bushings due to insufficient oil pressure in the line, which leads to oil leakage, as well as a malfunction of the oil seal, when oil will fly into the exhaust pipe, appearing at the outlet in the form of strong smoke when the pipe is heated, and sometimes even drain from the pipe in the form of drops. This situation is extremely dangerous, as it can “suck” all the oil from the engine sump;
Cracks in the jacket of the cylinder block or cylinder head, oil getting into the cooling system;
Low-grade oil, which leads to intense wear of the rubbing pairs, overheating of the engine, and as a result, rapid failure of all seals, which simply “dumb”, which leads to oil leakage through the seals and gaskets;
Squeezing out the pressure sensor and leaking oil.
How to eliminate high oil consumption?
A medium repair or a major repair will help, depending on the degree of wear of the CPG, crankshaft liners, and the condition of the cylinder head, which is determined when disassembling the power unit.
Replace valve seals. This operation will give a positive result if the valve guides are not worn, otherwise the replacement will only have a short-term effect and the seals will again begin to leak oil into the combustion chamber. This is due to the fact that the valve will not operate in the center of the bushing, but will deviate towards the wear of the bushing, while pressing on the edge of the oil seal, which will quickly disable it.
The way out of the situation is to replace the bushings, for which you will have to dismantle the cylinder head for repairs.
Drain the low-grade oil, flush the engine, fill with oil that meets the manufacturer's instructions in terms of quality and quality. The lower the viscosity of the oil, the thinner it is and the more capable it is of leaking through oil seals and other engine seals. The issue of oil quality in this case is only trust in the retail outlet or car service where it is replaced.
Replace faulty seals and gaskets.
Restore or replace the oil pump to create the required pressure in the line.
Avoid aggression when driving a car, which will extend its service life and eliminate the problem of high oil consumption.
Monitor the level and always use the oil prescribed by the manufacturer, without skimping on low-grade analogues.
Most car enthusiasts encounter the problem of increased oil consumption while operating a vehicle. The reasons for this behavior of the motor may be different. Below we will talk about what circumstances cause the oil to burn and how to prevent a major overhaul of the power unit.
Why does the engine start to eat oil intensively?
We should start with the fact that among internal combustion engines there is not a single one that does not consume oil during operation. This circumstance is inherent in the principle of their operation and motorists just have to put up with it. Even an engine installed in a car that has just left the showroom will consume a small amount of oil. But as the vehicle’s mileage increases, the oil consumption parameter will only increase. A new engine in a standard city car for a range of seven thousand kilometers on average consumes no more than 100 grams of lubricant.
The nature of excessive oil consumption by the engine can be determined by the intensity of the problem. The power unit can “eat” lubricant:
- in small volumes, slightly exceeding the norm specified by the manufacturer;
- in volumes significantly exceeding the norm;
- with enviable consistency and in the same quantity;
- periods: consumption will either be within the normal range or exceed it.
The main reasons for burning oil
There may be several reasons that influence increased engine oil consumption. Therefore, it is worth reading and understanding them in detail.
1. Problems with the operation of the cylinder-piston group
Stain on the piston
Often the basis for problems with increased lubricant consumption is the deplorable condition of the cylinders, pistons and their rings. If the engine is working properly, then when the operating temperature is reached, the gap between the cylinder walls and the piston becomes minimal. Accordingly, the rings will fit as closely as possible to the cylinders. As the vehicle is used, the cylinder changes shape. At the point where the maximum linear speed of the piston is reached, that is, in the middle, the diameter of the cylinder will gradually increase. Due to the lateral load coming from the connecting rods, wear will be uneven. Thus, the cylinder becomes oval-barrel-shaped. With such deformation, the rings wear out and lose the ability to track the shape of the cylinder walls.
In the event of a significant deterioration in the performance of the piston system, the gaps located between the cylinder wall and the oil scraper rings increase (stuck rings). For this reason, the ring does not completely drive off the oil, and the liquid remains on the walls. Once the lubricant enters the combustion chamber, it becomes black smoke and is released through the exhaust system. These processes are the reason why vehicles with worn-out engines become so “smoky.”
High consumption of motor lubricant can be accompanied by not only black, but also blue exhaust. To be sure of the exact cause of the phenomenon hidden behind the increased consumption of lubricant, it is worth using a gas analyzer. There is also a popular way to check, which consists of covering the exhaust pipe for a short time with a clean piece of paper. The presence of grease stains on paper in the exhaust indicates the presence of oil.
Oil can also enter the combustion chamber and come out of it as black smoke due to wear of parts in the friction pair, consisting of the valve and its guide. During constant operation of the machine, the valve play at the seating point increases. Next, this part will break the oil seal, which includes an oil seal that collects excess oil.
If a block made of aluminum is installed in the engine, then with constant overheating of the engine, the process of warping of the cylinder block will begin. This will cause increased lubricant consumption by the power unit.
The most unpleasant situations when oil burns become noticeable to the car owner are severe damage to the cylinder-piston group. These include, for example, a broken ring.
2. Problems with the cylinder head and piston ring wear
The only problem area in a working engine, through which lubricant manages to get into the combustion chamber, is the valve guides. In order for this friction pair to function properly, it must be provided with oil, even though modern bronze or cermet bushings can function with a small amount of lubricating fluid. The valve stem seals limit the amount of oil that remains on the valve stem. But these structural elements are also subject to wear and tear over time. The result is a gradual increase in the amount of lubricant remaining on the valves. And if this feature on the exhaust valve is almost invisible, then from the intake valve excess oil is very quickly carried away by air into the combustion chamber.
The main symptom of wear on the valve stem seals is increased smoke when re-gasping. This happens due to the fact that the throttle valve closes at increased speeds. In this case, the vacuum value in the intake manifold is at the maximum limit. Accordingly, the oil will, in the literal sense of the word, be sucked through the guides into the cylinder. If you do not pay attention to the problem, the guides will wear out and transverse play of the valve will occur. But even replacing with new valve stem seals will not help solve this problem.
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Among the reasons for increased wear of valve stem seals and rings, we highlight:
- high mileage;
- constant overheating of the power unit;
- incorrectly selected viscosity or type of lubricant;
- incorrectly selected additives;
- constant over-gassing;
- daily use of the motor at maximum power;
- cold start.
3. Problem with valves or ducts of the crankcase ventilation system
The main task of the crankcase ventilation system is to maintain a low pressure level in it. This is the only way to reduce lubricant leakage through the seals. In order for the piston rings to function correctly, the crankcase gas pressure must be at a certain value. Relief of excess pressure is assigned to a special bypass valve. If it fails, for example due to jamming or contamination with soot, the pressure value will increase, and it will become difficult for the piston rings to remove lubricant from the walls with the same efficiency. This causes an increase in engine oil consumption.
4. Problem with wear of cuffs, gaskets and seals
It’s worth starting with the simplest and least expensive problem, which is a leaking crankshaft oil seal. This defect is easily detected by the car owner after parking the car overnight. If there is a puddle or even small oil smudges under the car, then the motorist needs to urgently replace the oil seal. In addition, a visual inspection of the engine compartment will help identify the problem. If there are traces of oil, we can conclude that the edges on the crankshaft oil seal are worn. There are many reasons for this defect. However, the most common is operational wear. Over time, the seal material, that is, rubber, simply dries out. This is how the leak appears. The reason may also be the use of aggressive chemicals by the car owner.
Problem with the cylinder block gasket. Such a defect is not associated with operational wear or the use of poor-quality lubricant. The problem lies either in the overheating of the motor, or in the power bolts not being tightened to the limit. Due to this, the gasket loses its properties and begins to leak. The defect in question should not be ignored, because it can cause water hammer or engine jamming. If there is a problem, the motorist must change the gasket.
There is a problem with the gasket in the oil filter. In most cases, this phenomenon can be encountered when using a low-quality filter, or due to an unscrupulous approach to the work of auto mechanics. Replacing the part or turning it until it fits tightly will help remove the defect.
Problem with oil seals. This defect most often affects the increase in engine oil consumption. The caps are located at the top of the power unit head. The temperature here is always high, and during overheating its value reaches a critical limit, which causes a leak.
5. Oil of inappropriate viscosity
Due to constantly tightening environmental requirements, automakers have to fight for every % to reduce mechanical losses by power units in order to achieve a reduction in fuel consumption. With regards to the cylinder-piston group, this manifested itself in the equipping of engines with thin rings that have little elasticity. These actions helped reduce friction and increase part life, but required drivers to use only those types of oil that have a low viscosity.
The higher the value of the lubricant viscosity parameter, the stronger the oil film on the surface of the parts. When using high-viscosity fluid in power units equipped with thin piston rings, the latter simply cannot completely clean the lubricant from the walls. This becomes the cause of oil burn, which in symptoms is very similar to problems with wear of parts of the cylinder-piston group.
Most modern power units are designed to use synthetic oils. For this reason, the use of mineral lubricant in engine operation will lead to a decrease in lubrication performance, the formation of scuffing and the entry of a significant amount of oil residue into the combustion chamber. The same problems will arise when using high-quality lubricant, but not the appropriate viscosity.
Reasons for increased oil consumption in the absence of smoke
The main cause of this problem is visible oil leaks, which were discussed above. But what to do in a situation where a visual inspection did not bring results and no leaks were found? You shouldn't make hasty decisions. If the engine begins to consume significantly more oil, then there is a leak. It's just not so easy to notice.
The problem may lie in one of the following details:
- Turbine. Such a structural unit of a vehicle not only needs constant lubrication, but it is also cooled by oil. If the shaft is heavily worn, oil may gradually leak onto the pump and turbine wheel. Along it it rushes into the intake, then into the combustion chamber, and at the last stage of its journey straight into the muffler. The result of this route appears in black smoke.
- Distributor (ignition distributor). When the power unit is equipped with such a device, oil can easily leak through the O-ring. To determine the problem, you will need to remove the distributor cover and conduct a visual analysis of its components (if there is oil, it will be impossible not to notice it).
- Defect on the camshaft plug. This part is installed on those engines with a pair of camshafts. Less commonly, it can be found on a single shaft, and then only if the motor does not have a distributor. If there is a defect, then oil will flow through the O-ring.
Timely maintenance and proper operation of the vehicle will guarantee low costs for engine repairs and the purchase of oil. The concept of “correct operation” means moderate operation of the motor. When you constantly give the engine high speeds during daily trips, then it won’t be long before the lubricant consumption increases.
Seal
Many motorists sooner or later have to deal with the problem of excessive oil consumption. Most often it manifests itself in used cars, the power unit of which has a high mileage. But why does the engine eat oil and what could be the reasons? This is exactly what we will talk about next.
Today, the problem of increased oil consumption is very relevant, and many vehicle owners are actively struggling with it. Automakers also do not stand aside and are trying to reduce oil consumption, however, no matter what they do, the problem remains the same, since during engine operation some of the lubricant is burned and this is a completely normal phenomenon. From the above, it becomes clear that during its operation, each internal combustion engine will consume a certain amount of oil.
It is considered normal when oil consumption does not exceed 0.25% of gasoline consumption. It follows from this that a working engine should consume 25 grams of oil per 100 liters of gasoline. If more oil is consumed, then repair work must be carried out, as otherwise the situation will only worsen. New cars invariably use oil, but this figure will continually increase as the mileage increases.
This fluid provides lubrication of all rubbing parts of the engine, including each of its cylinders. It is this liquid substance that allows the pistons to move freely inside the cylinders without causing even the slightest jamming. To prevent oil from penetrating into the combustion chamber, oil scraper rings remove excess oil from the cylinder walls, and it returns to the oil pan. If these rings become worn, the oil will eventually not be removed properly, causing it to enter the combustion chamber.
Why does the engine eat oil?
Often, increased lubricant consumption can be caused by cylinder wear. In this case, it is possible to fix the problem only by boring or replacing the cylinder block. This is a fairly expensive repair that cannot be avoided.
Another reason is wear of the valve stem seals, which remove oil from the valves. It is important to understand that they also have a certain resource and over time their properties will be lost. As a result, the oil will not be removed in the required amount and will again begin to penetrate the combustion chamber. If the reason for the overconsumption lies in these seals, then they must be replaced. Their cost is relatively low, and replacement can be done at any service station. Leaks can often be caused by ordinary leaks.
Sometimes oil begins to leak from under the cylinder head gasket, and in this case this phenomenon can only be eliminated by replacing this very gasket.
What to do if the engine eats oil
If the engine eats oil, then first of all you need to identify the cause of this phenomenon. It can not only get into the combustion chamber of the engine and burn out along with the fuel-air mixture, but also simply leak out due to leaks in certain components of the power unit. Next, let's look at everything in more detail:
- Check all oil seals and gaskets of the power unit. If oil leaks are detected, the seals should be replaced.
- Inspect the valve cover for leaks. If they are present, replace the gasket. It wouldn’t hurt to check the lid itself for evenness, since it could have become deformed due to overheating and in this case only replacement will help.
- Inspect the pan and oil filter. If necessary, tighten the threaded connections.
- Check the condition of the camshaft and crankshaft seals. Replace them if necessary.
If after carrying out these diagnostic measures the problem of excessive oil consumption remains relevant, then in this case it is of an internal nature and in order to eliminate the malfunction you will have to resort to quite expensive and moderately complex repairs. If the exhaust has a bluish tint, then this is a clear sign of CPG wear.
Conclusion
From all of the above, it becomes clear that there can be a huge number of reasons for increased oil consumption. If you notice blue smoke from the exhaust pipe, this is not the best sign indicating the need for expensive repairs at a service station. If there are regular oil leaks from under the gaskets or seals, then it will be enough to replace them. Most often, this will not require large financial investments or the need to contact experienced auto mechanics.
Unfortunately, in our world there are many technically uneducated individuals who, knowing that a pit bike smokes and consumes liters of oil, still continue to ride! "So what? He's coming! Add more work and it will work for the rest of its life!” We want to disappoint you, it won’t work for the rest of its life, and very soon you will be writing about how unreliable pit bikes are and how engines quickly break down. And the whole point is not in the engines, but in the stupid owners. Well, for wiser people who follow technology and want to know what the consequences of long-term driving on a motor that consumes a fair amount of oil, we will sort it all out in this article. The matter. The point is that if an engine consumes oil, this does not mean that the entire piston system suffers, the entire engine suffers as a whole. Firstly, because the oil level is not stable, every now and then oil starvation occurs in one or another engine component. But this is nothing compared to how the cylinder head suffers. As you understand, the oil that gets into the combustion chamber is not completely it burns out, and this is not 2 strokes, where the exhaust flies straight into the muffler. Here all this gas-oil mixture goes straight to the valves. And once on the valves, the oil settles, forming a dense, fairly hard, viscous carbon deposit!
Carbon deposits, by the way, form not only on the valve strut, but also on the working surface of the valve, the same one that is responsible for the tightness of the combustion chamber during operation. For comparison, here are two valves: the first is from a motor that ate oil, and the second from a normal, serviceable engine. 
And this kind of crap forms on your engine, if you are smart enough to drive it. What are the consequences? First of all, the tightness is lost, the valve is no longer able to fulfill its direct duty. Secondly, this is a completely expected increase in the weight of the valve. Naturally, the weight will deviate from the factory calculations and the normal limit, as a result - unstable operation of the motor. But these are just the beginnings, the most interesting things are yet to come!
In addition to the valve, the oil also settles on the cavities of the cylinder head, forming a huge amount of carbon deposits there, which prevents the free exit of exhaust gases. 
At one point, there is so much carbon deposits that it can simply suddenly fall off in a piece, stand across it, which is why the valve will not close and will receive a good kick from the piston. In short, you get bent valves. 
And the second scenario: at one point the carbon deposits will coke the tiny gaps of the valve guide, it will stop halfway, and the inertial force of the engine will do its wonderful job and the valve will break! 
The torn part of the valve goes straight into the cylinder and, in addition to grinding the entire head, it also pretty much gouges the piston, causing it to jam, and the crank, under the influence of the same inertial force, will tear it off at the roots. 
Bottom line: We really hope that when you notice the primary signs of oil consumption, you will not continue to drive stupidly, but will start making repairs.
