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What is the temperature of the engine oil in the engine. What is the oil temperature in an internal combustion engine? Why engine oil temperature is important

The principle of operation of an internal combustion engine (ICE) is such that the result of its operation is a large release of heat. The heat inside the engine, especially in its cylinder-piston group, reaches 300°C and higher, if we consider diesel engines. Therefore, the engine oil temperature fluctuates widely as the lubricating fluid moves through the lubrication system inside the internal combustion engine.

Main functions of motor oils

A car engine has many components and parts. Their surfaces are constantly in contact, creating friction between themselves. The result of this phenomenon is increased wear. In addition, friction consumes a significant portion of the engine's efficiency, which is converted into heat.

High temperatures provoke expansion of the materials from which the parts are made. Expansion processes are accompanied by a decrease in the gap between the contacting surfaces. There will come a time when this gap simply disappears, and the internal combustion engine will jam - this is what will happen if the unit operates without engine oil.

Engine oil performs a vital function, without which the unit simply cannot operate. It reduces the coefficient of friction by forming a thin oil film between contacting surfaces. In addition, lubricant increases engine efficiency and reduces wear of parts, promotes less heat generation, and also effectively removes it from rubbing surfaces. In addition to these functions, others are implemented:

The hydraulic fluid can also be controlled by pressure on hydraulic valve lash adjusters, hydraulic timing belt tensioners, and variable valve timing systems.

Lubrication system design

The most successful lubrication systems provide different amounts of lubricant, depending on the functional characteristics of the parts. Oil comes to the most critical components and parts under pressure. Less loaded areas receive it by splashing or natural flow. Such lubrication systems are usually called combined.

An oil pump is used to ensure the pressure of the working fluid inside the line. Experiencing such pressure, lubricating fluid from the engine crankcase is supplied to the oil filter. There it is cleaned and supplied to the bearings that ensure the rotation of the crankshaft. Next - to the piston pins, camshaft, valve rocker arms. If there is a turbine, the shaft on which it rotates will need oil. In addition, heat is removed from the inner surface of the pistons. The lubricant seals the gap between the oil scraper rings, as well as the piston compression rings and the engine cylinders, and prevents them from sticking. The liquid gets there, spraying from the nozzles at the bottom of the cylinder-piston block.

Next, the lubricant returns back to the oil pan. Along the way, it is sprayed by the crank mechanism, creating fog. It lubricates all the parts it envelops. From the mist, the lubricant condenses, returning to its original state and position. Thus, the cycle repeats again and again.

Temperature range of oil composition

The operating temperature of the oil varies widely - from ambient air to 180 degrees when passing through the cylinder-piston group. In this case, the metal surfaces of the pistons and cylinders are heated to 300°C. As it circulates through the engine, the oil composition tends to evaporate and burn away. To prevent hydrocarbon vapors from igniting inside the engine, it is necessary that their combustion temperature be higher than the one to which they are usually heated. This ability is determined by such an important parameter as the flash point of the oil.

To determine this parameter, the oil is placed inside the crucible. It is then heated until the fumes begin to flare up from the flame. The temperature is immediately measured. Usually it ranges from 220°C and above. This is enough to prevent working fluid vapors from igniting inside the engine. This parameter is not critical, so manufacturers do not indicate on the canisters what the ignition temperature of the oil is.

By the way, diesel vapors ignite at a much lower temperature, about 55–60°C. Having effective water cooling, it is possible to reduce the upper temperature limit of the oil composition to 105–115°C, which is a fairly significant indicator.

Viscosity-temperature characteristics

The stability and efficiency of their operation depends on the viscosity characteristics of lubricants. Viscosity, as well as the viscosity index, are one of the most important indicators, since they change during the transition from very low (-40 ° C) to high operating temperature conditions of the power unit.

According to the classifier of the American Society of Automotive Engineers SAE, motor oils are winter (0W, 5W, 10W, 15W, 20W, 25W), summer (20, 30, 40, 50, 60), as well as all-season, which are commonly used everywhere - for example, 5W30 or 10W40. The diagram shows the temperature ranges for using certain products. A very important indicator is the viscosity level in cold weather, as well as the pour point of the oil. That is, for example, 0W30 lubricant will allow you to start the engine at -40°C, ensuring its normal crankability. 5W30 will do the same down to -35°C and so on.

Overheating of lubricants is very dangerous for the engine. If the composition is heated to +125°C and above, it will lose its viscosity and will not be able to form an oil film. Therefore, it will penetrate into the combustion chamber through the piston rings, burning there along with the fuel. This is how soot deposits form and the lubricant burns out. That is why it is necessary to periodically check the oil level. It happens that a viscosity mismatch leads to lubricant consumption of up to 1 liter per 100–200 kilometers.

It is very important to use working fluids with the viscosity recommended by the manufacturer. This parameter can be determined from the service book issued for each vehicle.

Before determining what the operating temperature of a diesel engine should be or any other optimal parameters, you should find out what its design and operating principle are.

Diesel engine features

This type of engine was invented back in 1824 by a French physicist who put forward the theory that by changing the volume of a body, it can be heated, that is, it can be rapidly compressed.

This hypothesis found practical application only 70 years later. It was then that the first diesel engine was released. Its operating principle is as follows: self-ignition of the injected fuel occurs, which interacts with air during the compression process.

The diesel engine has a wide range of applications, from passenger cars, agricultural equipment to military equipment (tanks, sea vessels).

Advantages and disadvantages of a diesel engine

Like all other engines, diesel has a number of both positive and negative aspects. Main advantages:

• Firstly, diesel engines can consume any fuel, so there are no serious requirements for it.
• Secondly, the greater the mass and concentration of carbon atoms, the greater the calorific value of the engine and its efficiency.
• Thirdly, vehicles with diesel engines are more responsive due to the high torque at low speeds. Therefore, owners of fast sports cars prefer the diesel engine option.
• Fourthly, the carbon dioxide content in the exhaust is an order of magnitude lower than that of similar gasoline engines.
• Fifthly, it is more economical, since the cost of diesel fuel is less than the cost of gasoline.

Despite such an impressive list of advantages, the diesel engine also has a number of disadvantages:

• Firstly, the cost of a diesel engine is higher than the cost of a gasoline engine, since due to the high mechanical stress that occurs during operation, the parts must be of high quality and durable.
• Secondly, the power of gasoline engines exceeds the power of diesel engines.
• Thirdly, in winter the likelihood of solidification is greater than that of gasoline.
• Fourthly, the operation of a diesel engine must be extremely careful and careful, since if you do not take care of it, you will have to carry out repair work, which will cost a lot of money.

Combustion phases

The engine's operating process is divided into four parts. The first is the injection of a combustible mixture into the combustion chamber, in which there is high pressure.

Secondly, this mixture begins to ignite and burn. The third part is the formation of unspent mixture droplets, which then turn into soot. In phase 4, the combustion of fuel residues occurs in order to limit atmospheric pollution from them. Here a lack of oxygen is manifested, this is due to the burnt mass of fuel in the previous parts.

Parameters of diesel engines

Many car owners ask the question what the operating temperature of a diesel engine should be. But to answer it, you should pay a little attention to the main parameters that affect the operation of the motor. The number of strokes is important in the operation of the motor, that is, there are two- and four-stroke.

The power of the unit also depends on the torque. The operating temperature of a diesel engine is determined by the degree of compression of the gas-fuel mixture, so the temperature is directly proportional to compression. Thus, as compression increases, the temperature will also increase, as a result of which the intensity of this process will increase, increasing the efficiency. It is worth remembering that the most efficient work is done when the fuel mixture burns evenly.

An important parameter to achieve the best possible performance is the operating temperature. The operating temperature of a diesel engine must be maintained based on the design and purpose of the engine. This fact determines whether the temperature is normal or not.

Volkswagen operating temperature

What is the operating temperature? This question is asked by many owners of these cars. As you know, each make and model of car, depending on the type of engine, has its own operating temperature.

As a rule, the operating temperature of a Volkswagen diesel engine is in the range of 90-100 degrees Celsius. Sometimes it happens that the dashboard shows a temperature higher than it actually is. This happens often on certain brands of Volkswagen cars. But there is no need to rush to change the equipment; first you need to contact the service for a technical inspection and determine the cause of the malfunction.

Mercedes operating temperature

The operating temperature of a Mercedes diesel engine depends on many factors. First of all, these are the operating conditions of the car. Then the thermostat type. Also, depending on the region of residence, be it Siberia or more southern regions, the thermostat is adjusted to the optimal temperature.

The normal operating temperature of a Mercedes diesel engine can range from 80 to 100 degrees. On powerful engines from 220 horsepower, set the thermostat to 75-78 degrees Celsius. For cold regions, on the contrary, up to 97 degrees and above.

Opel operating temperature

The operating temperature, due to the fact that it is under high pressure, can sometimes exceed the normal level by several points. Usually it fluctuates around 104-111 degrees Celsius.

Opel cars have a cooling system. When the upper operating temperature limit is exceeded, the fan turns on and quickly cools the engine to the minimum value.

KamAZ operating temperature

A very popular question among owners or those planning to become owners is what is the operating temperature of the KamAZ diesel engine. The answer to this question is the range of 95-98 degrees Celsius.

At a given temperature, the fuel burns completely, and most of the allowable clearances in the engine are selected. If the operating temperature is too low, engine performance may be adversely affected.

Diesel engine oil

The main task of oil and other lubricants in the engine is to significantly reduce friction between parts, which increases their service life. The choice of lubricant depends on the type of engine and the tasks assigned. The working fluid in a diesel engine depends on the engine coolant. The difference is 10-15 degrees Celsius. The upper threshold of his normal temperature is 105 degrees.

In addition to temperature, the oil must also have optimal parameters to ensure maximum useful engine operation: viscosity and lubrication. Viscosity should be determined based on weather conditions and air temperature. Because if you choose the wrong oil with the wrong viscosity, the operation of the engine and its parts may be disrupted. Lubrication has two types: boundary, hydrodynamic. Boundary lubrication involves removing used oil from engine parts, and introducing a portion of new oil to them. Hydrodynamic is that the oil is constantly renewed, lubricating the parts. More modern engine models use the first lubrication option.

Increase in operating temperature

A sudden increase in engine operating temperature can cause more harm than under-temperature. In this case, the engine parts begin to operate in a hydrodynamic lubrication mode, which leads to a decrease in oil viscosity. Then the oil does not completely cover all parts, which subsequently leads to damage to the engine mechanism. Oil levels will be normal thanks to constant top-ups. When the engine overheats, the housing and bearings first become unusable, but the pump remains normal. This phenomenon is similar to problems caused by insufficient lubrication.

Starting diesel engines in winter conditions

Almost all people know that it is necessary to warm up the car engine before driving. Especially during the winter period. If we consider this warming up process in detail, we will see the following: first of all, the pistons begin to heat up, and only then the cylinder block. If you start driving with a cold engine, then the oil, which has a thick consistency, will not flow in the required quantities. And in the end, this event can lead to breakdown.

It should be noted that excessive heating of the car for wear and tear is very harmful. This reduces the service life of engine parts and the entire vehicle. In order to warm up the car correctly, you need to bring the fluid temperature to 50 degrees Celsius using idle speed. After this, you can safely start driving without exceeding 2500 rpm. After heating the oil to the operating mark, you can add gas.

By fulfilling these conditions, you can keep not only the engine intact, but also your budget. If the engine refuses to start, then specially invented additives should be used. Due to their composition, they are not waxed. They are added not only as independent additives, but also in combination with fuel, maintaining optimal proportions.

Automotive engines must cope with severe thermal loads in all operating conditions. It is for this reason that high demands are placed on the characteristics of motor oil. Lubricant is used to prevent friction between the contacting parts of the power unit. Motor oil separates these parts and quickly passes through all oil channels. Flash point is an indicator that indicates the conditions under which the evaporation of an oil liquid begins.

Whether there is a h Is the viscosity of oils dependent on temperature? Of course. When manufacturing a car engine, automakers must decide on the viscosity of the oil, which can increase/decrease with temperature changes.

The boiling point is determined as follows. Motor oil is heated in a special container. Then the temperature begins to gradually increase (by two degrees per minute). The increase continues until the lubricant begins to boil and burn.

The auto-ignition temperature indicates the presence of low-boiling elements in the oil liquid. This parameter is related to the volatility of the product. High-quality petroleum products can withstand extremely high temperatures (above two hundred and twenty-five degrees Celsius). Low-viscosity motor oils evaporate at high speed. Because of this, they need to be changed frequently.

From -35 to +180 degrees - this is the usual minimum and maximum operating temperature limit for consumables. The temperature of the engine oil depends on the design features of the engine, as well as on climatic conditions. To obtain good temperature-viscosity characteristics, the lubricant is made thicker with the help of special additives, which reduce the degree of change in the parameters of the petroleum product due to temperature changes.

Temperature ranges

In an ordinary water-cooled motor, the temperature should be between eighty and ninety degrees. Viscosity can decrease to 10 mm 2 /s. Because of this, the lubricating film becomes too thin. It is unable to properly protect all engine parts while driving.

It is necessary to know the temperature ranges in which various motor oils can be used. Winter lubricants are labeled with one number and the letter “w”. Oils for summer are marked with one number. All-season petroleum products, which can be poured into the engine at any time of the year, are marked with two numbers and the letter “w”. A special table has been developed that contains information about all ranges.

Oils are intended for gasoline/diesel internal combustion engines. There are also universal motor oils. Oil performance depends on the base fluid and additives. Oils are divided into semi-synthetic, synthetic and mineral products.

Expanding the temperature range leads to an increase in the quality of the lubricating fluid. There is a direct relationship between the viscosity of motor oils and temperature. The higher the temperature at which the engine operates, the thinner the oil product.

Low temperature conditions

Not only the street temperature is important, but also the operating temperature, which depends on the vehicle’s mileage and load. The internal combustion engine of any car usually has 2 modes of lubricant pumping:

• boundary (the piston system is lubricated without compression);
• hydrodynamic (the crankshaft is lubricated with compression).

Low-temperature oil characteristics include the following:

• turning ability. Indicates dynamic viscosity, the temperature range in which it is possible to start the power unit;
• pumpability. Shows the speed at which motor oil passes through the lubricant complex.

It must be said that the temperature range of crankability differs by five degrees from the range of pumpability (increasingly).

High temperature conditions

What happens if the running engine has heated up to the optimal temperature, but the oil viscosity has not decreased to the required value? It's OK. You just need to wait until the lubricant takes the right consistency.

Too much engine temperature is more dangerous than too little. High temperature conditions can lead to combustion of petroleum products. When the oil boils, it bubbles and smokes. This occurs at temperatures from two hundred fifty to two hundred sixty degrees (the range may expand slightly).

At high temperatures, the thickness of the oil decreases. Consequently, it protects spare parts less well. Reducing the gaps between different parts leads to the fact that the power unit does not operate at full capacity. If the temperature of the car oil increases to one hundred and twenty-five, it will begin to burn out along with the fuel when it passes through all the pistons. The lubricant content in the fuel will be small, its consumption will increase, and you will need to constantly refill new ones.

Flashes and freezing of motor oil

Flashes

The condition at which oil ignites when a gas flame is brought close to it is called flash point. When the lubricant is heated, special vapors (from evaporated oil) accumulate, which promote combustion.

This indicator indicates how volatile the oil is and the level of its purification.

Freezing

The condition in which car oil loses its viscosity and mobility is called freezing point. When solidified, the viscosity increases sharply and the paraffin crystallizes. The lubricant becomes harder and more flexible.

Tips for selecting and replacing lubricant:

1. A lubricant with high viscosity at high temperature conditions is used in sports cars.
2. It is not advisable to pour it into an ordinary car. When choosing a car oil, it is better to rely on what is written in the operating manual.
3. It is better not to fill the engine with oil whose characteristics exceed those recommended by the car manufacturer.
4. The shade of the petroleum product does not matter much. Additives contained in the oil give it a black color.
5. It is better to change your car oil at intervals determined by the car manufacturer.
6. If the car often drives in off-road terrain, it is necessary to change the oil product a couple of times more often than prescribed in the manual.
7. If the shade of a consumable has changed, this does not mean that it has lost its own characteristics. Oil washes away deposits from the internal combustion engine that remain in it.
8. It is better not to mix mineral water with synthetics.
9. When topping up the motor, use the same lubricant that is already filled.
10. Flushing is not necessary if replacement dates are met.

What oil fluid should I buy to ensure reliable protection of the parts of my own car? Your best bet, of course, is to choose a product that your auto manufacturer recommends. Determining the optimal characteristics of a petroleum product for an engine is a complex process. The manufacturer conducts many different tests to determine which oil will be most suitable for any engine.

In real conditions, the range of permissible temperature conditions may expand. This is due to the climate, which in the Russian Federation is quite harsh (especially in winter). Every car owner should be able to select the optimal lubricant, based on the recommendations of the manufacturer of their car, as well as on real road conditions. This provides an opportunity to maximize the operational life of any vehicle, be it a car, a minibus or a truck.

When a car engine runs, a lot of heat is generated, which must be dissipated somehow. The high temperature that occurs in the cylinder-piston group rises to 300 degrees Celsius or more. In this regard, the operating temperature of the oil in the block is also quite high, but the characteristics of the lubricating fluid depend on it.

In what range does the temperature change?

The operating temperature of the oil in an internal combustion engine varies over a wide range, and at its maximum it reaches approximately 180 degrees. As for metal parts (pistons, cylinder surfaces), they heat up to 300 degrees. As the lubricant circulates inside the engine, it burns and evaporates. To prevent vapors from igniting, their temperature must be higher than the one to which they are heated. This ability depends on such characteristics as the flash point of the engine oil.

To determine it in practice, you need to place the oil in a crucible and start heating it until the vapors begin to ignite. The temperature at this moment is measured (usually it reaches 220 degrees or more). As a rule, this is enough to prevent the vapors from igniting inside the engine. This oil parameter is not critical, so manufacturers rarely indicate it on canister labels.

It should be noted that diesel vapors ignite at a much lower temperature - 55-60 degrees. With effective water cooling, the upper limit of the operating temperature of the engine oil is reduced to 100-115 degrees Celsius.

Dependence of viscosity on temperature

When the engine is cold started, the internal surfaces must be effectively lubricated. depends on the ambient temperature, so universal lubricating fluids sold in stores are not able to ensure efficient and smooth operation of the engine at any time of the year.

It is necessary to take into account not only the ambient temperature, but also other factors. The mileage of the car plays an important role. During a cold start, thinner oil ensures effective lubrication of metal surfaces, but with prolonged engine operation this property decreases.

As for oils that are too viscous, they cause increased engine wear when starting, although after reaching operating temperature the oil will effectively lubricate the rubbing parts.

Every motorist should know that water-cooled engines operate optimally when the temperature of the liquid in the cooling system is 90 degrees. In this case, the temperature range of motor oils will be 90-105 degrees. It is important not to exceed the upper limit, otherwise the lubricant will no longer create a uniform film on metal surfaces, which protects parts from friction.

It should be noted that car engine components are designed taking into account the fact that they will expand when heated. Therefore, the oil should not get hotter than it should.

Low engine oil temperature

We figured out what the engine oil temperature should be, but let’s consider what will happen if it drops significantly. In this case, the engine will operate with insufficient efficiency: the internal parts will not expand enough and the required gap will not arise between them.

Acids will also form in the lubricant. In an unheated engine, moisture condenses, which flows into the oil and mixes with combustion products. Emerging acids destroy light metals. In this regard, the engine oil temperature should be normal and not low.

In addition, oil that is too cold is thick, making it difficult for it to pass through the filtration system. The oil will bypass the filter element through the valve in the filter, and this will accelerate the wear of engine parts. Fluid leaks may also occur.

During operation, the temperature of the oil in the engine heats up during operation, withstanding significant loads caused by the operation of its components and parts. Therefore, lubricants must be of high quality and meet operating conditions. In order not to bring the engine oil to boiling point, you need to know what kind of lubricant to use.

Engine oil and engine temperature

Lubricating fluid is an important component for the operation of any engine. The document defining the classification and designation of oils used in internal combustion engines is the interstate standard GOST 17479-85, as amended in 1999. The requirements of this document are interrelated with the international standards SAE, API and ACEA, which determine the parameters of oils depending on the season and ambient temperature. The SAE standard defines the viscosity-temperature characteristics of a lubricant. The API standard specifies the use of lubricant, depending on the type of engine, its production date and technical parameters (for example, with or without turbocharging). The ACEA standard was developed by European manufacturers. It is similar to the API standard, but has more stringent indicators.

Based on these documents, motor oil can be gasoline, diesel and universal. The oil solution is made from mineral oil with the addition of various components and additives. Depending on the additives, the oil fluid in the engine unit is divided into: mineral, synthetic and semi-synthetic.

According to its structure, the oil solution is divided into three types:

1. . A special feature is its more liquid state, which makes it easier to start the car. During the warm season, the oil solution is not suitable for use, since during operation its viscosity will become less than the standard. The functions of protecting and lubricating units will be reduced to a minimum. Has alphanumeric markings.
2. Summer. Used at ambient temperatures above zero degrees. This liquid has a high viscosity and fluidity. Use in winter is not recommended, as the high viscosity will make starting the vehicle difficult. Has digital markings.
3. All-season. The most popular type of fluid among all drivers. Can be used at any time of the year at any ambient temperature. Has double marking.

The choice of oil has a direct impact on engine temperature. The power plant ranges from 70 to 90 degrees in winter. As the temperature rises to zero, you can start driving when the engine warms up to 50-70 degrees. In summer, components and assemblies do not need to be warmed up. You can start moving in natural conditions. At the recommended temperature conditions, the engine starts and runs reliably, and the cylinders are filled to the maximum extent. Some types of starters have a normal operating mode at temperatures from 100 to 110 degrees. Basically, this is a wound air-cooled unit, for example a two-stroke engine.

How does the engine lubrication system work?

The task of the lubrication system is to store, transport, clean and supply oil to the rubbing parts of the engine in order to reduce friction of mating parts, ensure a smooth start of the engine and prevent it from overheating. The task is accomplished by a complex of components and assemblies, which includes:

1. Engine crankcase (sump) with drain neck.
2. Oil pump.
3. Oil filter.
4. Radiator for cooling oil fluid.
5. Pressure reducing valve.
6. Pressure meter.
7. Temperature sensor.
8. Pipelines.

The operating principle of the lubrication system is based on the supply of a combined supply of lubricating fluid to the rubbing parts. Oil supply begins after the engine starts. The pump pumps oil fluid from the engine crankcase and supplies it to the engine for lubrication. After cleaning, the liquid under pressure is supplied to the crank and distribution mechanisms of the engine. Through the connecting rods, the oil solution is supplied to the engine cylinders. The heated oil liquid enters the radiator, where it is cooled. The oil fluid drains from the radiator into the sump.

The remaining components of the power unit are lubricated after creating an oil cloud. It is obtained as a result of the splashing of lubricant by the crank mechanism through the gaps and technological holes. After lubrication, the oil liquid enters the pan, mixing with the oil coming from the radiator, and the lubricant supply process begins anew.

Functionality of lubricating fluids

In order for the power unit to function stably, it is necessary to select the correct lubricant solution. Its selection is made according to parameters, the main of which are:

1. Viscosity. The main indicator of any oil. It means the ability of an oil fluid to maintain the proper level of fluidity while covering parts inside the engine. The degree of viscosity depends on the engine temperature and its own. As the temperature rises, the viscosity level drops.
2. Viscosity index. A value that determines the level of viscosity of a lubricant solution depending on its temperature. Increasing the viscosity index increases the temperature range in which it can operate. The indicator is different for each type of oil.
3. Flash temperature reading. A value that determines the level of low-boiling fractions in the oil liquid. In high-quality oils, flash occurs at temperatures of +230 degrees and above. If the oil solution is of poor quality, then low-viscosity components will quickly burn out and evaporate, and its consumption will increase.
4. Boiling temperature reading. An indicator at which an oil fluid loses its viscosity and lubricating properties. Its boiling will lead to contact between the rubbing parts of the power plant and its failure.
5. Ignition temperature reading. The amount of critical heating of the oil fluid. Its combustion begins when its temperature reaches +260 degrees. Ignition threatens to cause the engine to explode and cause injury to passengers.
6. Volatility. The oil solution begins to evaporate at a temperature of +250 degrees. Determination of volatility is carried out using the NOC method. At the specified temperature, one liter of oil must be boiled for one hour. If after an hour there are 900 grams of liquid left, then the volatility level is 10%. According to international standards, this norm should not exceed 15%.
7. Freeze temperature reading. The value that determines the level of loss of fluidity of the oil fluid. When the pour point is reached, the viscosity of the lubricant increases sharply or a process of increasing viscosity occurs with the solidification of paraffin, as a result of which the lubricant hardens.
8. Alkaline TVN value. A number that determines the alkaline characteristics of the oil obtained as a result of the addition of detergent and degrading additives. This is an indicator of the ability of an oil fluid to neutralize harmful impurities and acids resulting from the operation of the power plant. A decrease in the alkaline index indicates a decrease in the number of active additives, which can lead to corrosion of the internal parts of the power plant.
9. Acid number TAN. An indicator that determines the presence of oxidation elements in the lubricant. An increase in acid number indicates the presence of a large number of oxidation products. The acid number is determined when selecting oil for analysis. Typically, an increased acid value is associated with prolonged operation or high operating temperature of the power plant.

Engine oil operating temperature

The lubricant, depending on its characteristics, can be used in the temperature range from - 50 to + 170 degrees. The operating temperature of the oil in a warm engine and the preservation of its viscosity-technical parameters depend on the temperature regime of the engine. Normal engine temperature ranges from + 80 to + 90 degrees. With such heating, the starting unit has maximum efficiency. Oil lubricant warms up 10-15 degrees more than coolant. Therefore, the operating temperature of engine oil in a warm engine ranges from + 90 to + 105 degrees. It is not recommended to exceed the upper value. This threatens the lubricant with loss of characteristics and rapid wear of rubbing parts.

Changes in engine oil temperature

Engine parts are designed to expand when heated and return to their original state as the engine cools. The operation of the power unit depends on the temperature of the oil in a running engine. Excessively low or high heating of the oil in a running engine has negative consequences.

The low temperature of the lubricant can be considered + 80 degrees. With this indicator, the efficiency of the power plant decreases and its service life decreases. The parts of the power unit will have a slight expansion, which will lead to the formation of gaps between them and a decrease in compression. When the starter is slightly warmed up, moisture can condense and form acids in the lubricant, which will affect the wear of components and assemblies. Low degrees can cause the lubricant to thicken and freeze. This will affect its passage through the filter, creating a vacuum in the lubrication system and difficulties in the operation of the power plant.

High heat is even more dangerous than low heat. Heating the oil fluid above + 105 degrees leads to its viscosity sharply decreasing and fluidity increasing. Under load, the gap between the parts almost disappears, the parts of the crank mechanism come into contact with each other.

When the temperature reaches +125 degrees, the lubricant becomes highly fluid. This allows it to penetrate through the oil scraper rings and burn in the cylinder along with the fuel. The lubricant concentration decreases and its consumption increases. This is unacceptable and leads to wear and tear of the components and assemblies of the power plant.

The starting boiling point of motor oil is + 250 degrees. With this indicator, the lubricant has almost no viscosity, it is in a liquefied state and evaporates well. There is no protective film between the rubbing parts. An indicator that the oil has begun to boil is a sharp increase in temperature, about 3-4 degrees every minute.

Viscosity-temperature characteristics

According to interstate standard 17479.1-85, oils are divided according to viscosity, purpose and performance indicators. Based on viscosity, lubricants are divided into winter and summer classes. The class has a numerical designation; the letter “z” is added to the winter class.

According to their intended purpose, oil fluids are divided into groups that determine the operating mode of power units, with appropriate markings:

1. Unforced gasoline and diesel engines. Marked with the letter "A".
2. Low-powered gasoline and diesel engines. Marked with the letter “B1” - gasoline, “B2” - diesel.
3. Medium-boosted gasoline and diesel engines. Marked with the letter “B1” - gasoline, “B2” - diesel.
4. Highly accelerated gasoline and diesel engines operating in various conditions. Marked with the letter “G1, D1” - gasoline, “G2, D2” - diesel, “E1, E2”

The oil marking consists of numbers and letters. For example, the marking M-4з/6В1 means: M – oil, 4 – viscosity class, the letter “z” – winter, 6 – viscosity class in summer, B1 – medium-boosted gasoline power unit. The characteristics are the same as SAE 10w/20 oil.

The viscosity-temperature characteristics of oils according to interstate standard 17479.1-85 and the ratio with SAE are presented in the table:

Conclusion

The presented material showed what types and types of lubricants exist, and what temperature the oil should be in a running engine. It is always necessary to select high-quality lubricant for a car engine. This will prolong its operation and save the owner from early repairs.