Explanation of the hazards of burning engine oil and analysis of the causes

Thread Content

　　The engine is the heart of the vehicle and must be taken care of. High-quality engine oil not only helps to reduce engine wear and improve its operational efficiency, but it also saves fuel consumption, extends the interval between oil changes, and helps keep the engine clean. This extends the engine’s service life, allowing it to maintain optimal performance over time and thereby reducing maintenance costs. According to a survey, high fuel consumption has become one of the most common complaints among car owners these days. Oil burning, a problem that we used to think only affected older vehicles, is now gradually spreading to many new and nearly-new cars. Although the issue of oil consumption is not as concerning as fuel consumption, on the one hand, oil is relatively expensive, and on the other hand, excessive oil consumption always leads to concerns about potential mechanical problems. So it’s time to find out more about the issue of engine oil burning. 　　What is oil burning? First, we need to establish one thing: even the best-conditioned cars will experience some loss of oil during normal use. The main reasons for oil loss are as follows: 1. When the engine is running, an oil film forms on the inner walls of the cylinders to reduce frictional resistance. However, during the combustion of the fuel mixture, this oil film burns along with the hot combustion gases, resulting in oil loss. 　　2. In addition to lubricating the pistons, engine oil is also used to lubricate components such as the intake valves and exhaust valves. During the engine’s intake process, some oil inevitably gets drawn into the combustion chamber, and during the exhaust process, the high-temperature exhaust gases consume some of the oil at the exhaust valves. 　　3. Due to high-temperature oxidation, engine oil vapor is generated and drawn into the combustion chamber through the crankcase ventilation valve for combustion, a phenomenon that is particularly evident in engines with turbocharging. 　　4. Damage to the piston/cylinder wall results in an excessive gap between them, allowing engine oil to seep into the combustion chamber. 　　5. Carbon buildup in the engine due to factors such as engine oil can cause the piston rings to lose their elasticity, resulting in poor sealing and accelerated wear of the cylinder walls, which leads to a rapid decrease in engine oil levels. 　　6. The valve oil seals age and wear out, failing to provide an adequate seal; especially when the engine is not in use for extended periods of time, engine oil can easily flow into the cylinders through the gaps in the oil seals due to gravity, resulting in oil burning during ignition. 　　A decrease in oil level caused by the first three reasons is normal, whereas the latter three situations are abnormal; they lead to a rapid reduction in oil level, which is what we commonly refer to as \"oil burning\". 　　The hazards of burning engine oil The dangers of burning engine oil are not merely an increased consumption of oil; as too much oil participates in the combustion process, the likelihood of incomplete combustion in the combustion chamber increases, which in turn leads to the formation of carbon deposits and excessive emissions. In addition, various aspects of the engine such as its power, noise level, and fuel consumption are also affected. During driving, issues such as unstable idling and weak acceleration may occur, and it can also accelerate the wear and damage of the oxygen sensor, leading to clogging of the three-way catalytic converter. 　　The carbon buildup caused by engine oil burning up accumulates in the piston ring grooves. Over time, this can lead to the piston rings getting stuck, preventing them from performing their function of scraping oil away and increasing the likelihood of oil entering the combustion chamber. Furthermore, a stuck piston ring can also lead to accelerated wear between the piston and the cylinder wall, resulting in poor piston sealing and setting the stage for oil burning. This creates a vicious cycle; in severe cases, it can even cause cylinder scoring and render the engine unusable. 　　How to determine oil burning \"Oil burning\" poses a serious threat to vehicles. It not only causes the oxygen sensors in the vehicle to fail prematurely, but also leads to increased carbon buildup in the combustion chamber, unstable idling, weak acceleration, higher fuel consumption, and excessive exhaust emissions. In severe cases, insufficient engine lubrication can result in irreparable damage to the engine or even its total destruction, leading to high repair costs and even an increased risk of accidents. But for ordinary car owners, how can they determine whether their vehicle is experiencing oil burning? Oil burning when the engine is cold: Method of detection – Park the vehicle for one night, and upon starting it for the first time in the morning, observe the exhaust gases emitted. If the exhaust is a thick blue smoke, it indicates that the vehicle is experiencing oil burning. If the blue smoke disappears after the engine has warmed up, then this type of oil burning is considered oil burning at low engine temperatures. 　　Reason analysis: It is mainly due to the aging or damage of the valve oil seals, which results in poor sealing performance and allows engine oil to enter the cylinder from the valves. 　　Excessive oil burning under sudden acceleration Diagnosis method: After the engine is warmed up, whether during sudden acceleration or while idling, if the engine speed rises rapidly, blue smoke will be emitted from the exhaust pipe, indicating that the vehicle is experiencing oil burning. 　　Reason analysis: The main cause of oil burning during sudden acceleration is poor sealing between the inner wall of the cylinder and the piston rings, which allows oil to flow directly from the crankcase into the combustion chamber, resulting in oil burning. 　　Oil burning at any time. Method of detection: Blue smoke can be seen as soon as the engine is started; at this point, oil burning in the engine is quite severe, and it may even pose a safety hazard. 　　Reason analysis: Severe engine wear leads to poor sealing, creating favorable conditions for oil burning. It must be sent for repair urgently at this point to prevent more serious failures or damage. 　　How to avoid oil burning If you notice that your vehicle is experiencing oil burning, especially if the oil level is low, it is necessary to top up the oil promptly and take the vehicle to a repair shop for maintenance. It is also recommended that car owners keep a small spare bottle of oil in the trunk for emergency use. After taking the car to a 4S shop, as a general rule, the shop will replace parts such as piston rings and intake valve seals, depending on the cause of the problem, in order to resolve the oil burning issue. 　　But for many car owners, the greater concern is how to prevent their vehicles from burning engine oil, and this starts with regular maintenance. 　　There are considerations when choosing engine oil. To avoid oil burning, one can start by addressing the root cause: by selecting an engine oil with a low volatility rate, it is possible to prevent oil burning caused by the evaporation of the oil. Additionally, choosing an engine oil with a slightly higher viscosity can also improve the sealing between the piston and the cylinder, reducing the likelihood of oil burning. It should be noted that when choosing engine oil, it is advisable to opt for products from well-known brands that offer quality assurance. 　　The new vehicle should be broken in as required; be careful while driving during the breaking-in period. Follow the requirements for the running-in period; do not drive aggressively. 　　The fuel quality must be satisfactory. As mentioned earlier, carbon buildup inside the engine cylinders can not only cause the piston rings to stick, reducing their ability to scrape oil away, but it can also damage the inner walls of the cylinders, leading to oil burning. To prevent oil burning, one can start by addressing carbon buildup. 　　As a major cause of carbon buildup, oil quality issues must be given priority attention first. Low-quality fuel contains higher levels of sulfide impurities, which on one hand corrode the valve seals and cause oil leakage, while on the other hand they undergo oxidation to form gel-like substances that lead to carbon buildup in areas such as the piston ring grooves. To reduce carbon buildup, the engine also needs to be driven at high speeds from time to time; it cannot operate at low speeds for extended periods. 　　Don’t skimp on regular maintenance. In addition to changing the engine oil and oil filter on time, it is also necessary to replace the air filter promptly. If the air filter is clogged, it will prevent proper airflow, causing the intake pressure to drop and creating a vacuum that allows engine oil to seep into the combustion chamber, leading to oil burning. In summer, due to the hot weather, the oil consumption is higher than usual. The inspection method is simple: first pull out the oil gauge, wipe it clean, insert it again, then pull it out once more; by checking the level of oil, one can determine the situation. If a loss of engine oil is detected, it should be replenished promptly. Additionally, during routine inspections, if the engine oil contains impurities or has a gasoline-like odor, and the exhaust smoke is light blue, it indicates that there is a problem with the engine; the components may be suffering from abnormal wear, and maintenance is required. 　　Expert opinion: Some oil consumption issues are inherent in the design of the vehicle, and this is actually the main reason for complaints from car owners nowadays – the vehicle has no faults at all, yet it consumes a large amount of oil. Generally speaking, the most common cause of oil burning is oil leakage. Oil leaking up through the piston rings is the main problem. And the main reason for this is likely the issue with adjusting the gap between the piston and the cylinder wall. Regarding this clearance, it’s not the case that the smaller it is, the better; this depends on the material of the engine and its operating conditions. If the clearance is too small, sticking may occur due to the different coefficients of thermal expansion and contraction of the materials making up the various engine components. And if the gap is too large, oil leakage will occur. Generally speaking, the greater the degree of reinforcement in engine design, the higher the engine’s maximum speed and maximum power, or the better its dynamic performance; in such cases, this clearance needs to be larger. Therefore, theoretically, more oil burning should occur. Furthermore, the current traffic conditions are very poor; vehicles keep starting and stopping, and they restart immediately after shutting down. The temperature of the pistons fails to rise, and when this happens, it’s as if a small piston is moving around inside a large cylinder. As a result, oil burning becomes a common phenomenon. 　　Some car enthusiasts wait a few minutes or even tens of minutes after starting their vehicles in the cold morning before driving, waiting until the vehicle is warm. In fact, it’s sufficient to wait for a minute after starting the engine so that the oil can reach all the lubrication points; thereafter, it’s okay to control the speed moderately for five to six minutes after starting. Idling for a long time at low temperatures not only hinders the engine from warming up quickly but also increases fuel consumption.