Many friends know that the engine oil needs to be changed when the vehicle is maintained, but many people don’t know what the function of engine oil is and how to choose engine oil. Today, Xiao Jia will introduce you to the knowledge about engine oil!

Automobile lubricating oil can be generally divided into three types because of its different functions: engine oil, gearbox and differential oil, and grease (butter). The most common thing in vehicle maintenance is to change the engine oil.

Engine oil has five functions.

Lubrication function: the function of engine oil is to fill and lubricate the surfaces of moving parts and reduce the friction between moving parts. Its working principle is: the engine oil is pressurized by the oil pump and transported between the rotating parts, and an oil film is formed on the two friction surfaces to separate them, thus reducing the contact surface between moving parts, thus reducing wear and prolonging the service life of parts. There is surface friction between piston and cylinder, crank-connecting rod mechanism, cam valve train, gear rotating mechanism, etc., which must be lubricated by engine oil to ensure normal working conditions.

Cooling function: engine oil can bring back part of the heat generated between the rotating parts of the engine to the oil pan, and achieve the cooling effect through the oil pan wall. Some engines are also equipped with special engine oil radiators to achieve better cooling effect, so as to ensure the normal temperature between the rotating parts of the engine and keep the engine in normal working condition for a long time.

Sealing function: The engine oil also has a sealing function. For example, the engine piston ring and the cylinder wall are filled with engine oil, so that the contact surface and the gap have both a lubricating function and a sealing function, so that the piston can reduce air leakage when inhaling and compressing, and ensure the normal working compression ratio. If the piston ring and cylinder wall are worn, the sealing effect of engine oil can be improved by adjusting the viscosity of engine oil or adding engine oil additives, thus improving the working condition of the engine.

Cleaning function: The engine oil is pressurized by the oil pump and transported between the rotating parts of various parts for lubrication and heat dissipation. At the same time, it can also wash and clean the rotating working surface of the parts, bring the dust particles entering the engine and the garbage generated by the work to the oil pan, and keep the engine parts, rotating working surface and oil passage clean and smooth through the oil collection net and oil filter, thus ensuring the normal operation of the engine.

Rust-proof function: The working environment of the engine is complicated, and the climate change in spring, summer, autumn and winter will easily cause the metal parts to rust and deform, which will affect the normal operation of the engine and shorten its service life. The oil is pressurized by the oil pump and supplied to all parts and metal surfaces through the oil passage to form an oil film to isolate the air, which can prevent the metal surface from oxidation and rust and improve the service life of the engine.

If the engine is likened to the heart of a car, then the engine oil is the blood of the engine, which is a necessary condition to ensure the normal operation of the engine. Understanding the knowledge of engine oil, correctly selecting and using engine oil, and regularly replacing and maintaining it are very important to ensure the normal operation of the engine and prolong its service life.

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Written by Yang Chen, video.

Editor: Wang Lihui, Wu Lirong

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Magotan’s exterior design is full of modernity and dynamic, and the front face design is simple and atmospheric, and the family-style air intake grille design is adopted, showing a dynamic visual effect. The overall style tends to be steady and exquisite, and the body lines are smooth, creating a strong sense of movement. Magotan can show its unique charm in both business occasions and daily travel.

Magotan’s body size is 4866*1832*1479 mm, and the wheelbase is 2871 mm, providing passengers with spacious and comfortable seating space. Its side lines are smooth and dynamic, with a front track of 1584 mm and a rear track of 1570 mm, which enhances the stability and handling of the vehicle. Magotan is equipped with 215/55 R17 tires. With the fashionable rim design, it not only improves the visual effect of the vehicle, but also ensures excellent grip and driving stability.

Magotan’s interior design is simple and exquisite, and the center console adopts a well-defined layout, with an 8-inch or 9.2-inch central control screen, creating a full-fledged atmosphere for the car. The steering wheel is made of genuine leather, which feels comfortable and supports manual adjustment up and down and back and forth, ensuring the driver’s comfort and convenience. The car is equipped with rich multimedia and charging interfaces, including USB and Type-C interfaces, which meet the needs of daily use. In addition, Magotan is also equipped with wireless charging function of the front mobile phone, which greatly facilitates the driver. The seat is made of high-quality imitation leather, and the main and auxiliary seats have the functions of front and rear adjustment, backrest adjustment and height adjustment, which improves the riding comfort. The rear seats can be laid down in proportion, providing more space for storage.

Magotan is equipped with a 1.4T 150 HP L4 engine with a maximum power of 110kW and a maximum torque of 250N·m, which is matched with a 7-speed dry dual-clutch gearbox and has excellent power performance.

The owner of car home said that Magotan’s exterior design is calm and atmospheric, and the raindrop intake grille makes him feel young and dynamic, while the horizontal chrome-plated strip adds the atmosphere of business and gentleman. The waistline design makes the car look slender, the duckling tail design at the rear is sexy and plump, and the design of four exhaust pipes is sporty and publicity, which shows the extraordinary charm of Magotan.

　　[Global Times Comprehensive Report] German Chancellor Angela Scholz visited the White House on the 3rd local time to hold talks with US President Biden. The visit was not accompanied by any media, business delegations and cabinet ministers, and no joint press conference was held after the talks between the two sides. The media have questioned what is hidden behind this "mysterious visit". Some analysts believe that Germany and Germany are full of contradictions on issues such as aid to Ukrainian tanks, the explosion of the "Beixi" natural gas pipeline and the US Inflation Reduction Act, which is full of protectionism. However, as the "younger brother" of the United States, German leaders can do nothing about it. Germany’s "Star" magazine recently published a cover article saying that "Big Brother is back". The cover cartoon shows Biden holding Scholz, who is only half as tall, while the latter looks up at Big Brother.

　　Leave it to the public for only four minutes

　　"Mysterious visit", DPA said on the 4th that Scholz held talks with Biden at the White House on Friday, but this meeting only gave the public four minutes to observe. In his public appearance before the talks, Scholz said in English, "I really appreciate the good cooperation between us" and the transatlantic partnership is "in a very good state". Biden praised Scholz’s "strong leadership" and support for Ukraine, and said that the two countries would "help Ukraine with Qi Xin" and "keep pace in all aspects".

　　Then the two began to talk behind closed doors. The report questioned that the talks were "too mysterious". There were no consultants and recordings for the talks between the two sides, and there was no joint press conference after the talks. The report also complained that Biden ignored Berlin in his previous "trip to Europe". Biden visited Ukraine and Poland a few days ago and only made a short stop at Ramstein Air Force Base in Germany. On the contrary, this is Scholz’s second visit to Washington since he took office.

　　The Associated Press quoted people familiar with the matter as saying that the meeting between Biden and Scholz lasted for more than an hour, and the focus of the discussion was to continue to promote "global assistance to Ukraine". However, even Scholz’s senior advisers were not allowed to attend the talks. When their talks ended, Biden said half jokingly that they "solved all the problems in the world". However, the official statement issued by the two countries after the meeting hardly provided more details of the talks, and did not disclose any possible agreements or plans.

　　The secret visit and talks angered the German opposition. German CDU leader Mertz questioned in an interview with "German Editorial Network" on the 4th: "No one in our parliament and the German public knows the contents of this visit." He accused Scholz of keeping his Washington trip secret, which was "unconventional".

　　The New York Times said that there is growing opposition in the United States and Germany to aid Ukraine, and Scholz and Biden are also facing the upcoming general election (German parliamentary elections will be held in 2025). Jens, a senior researcher at the German Marshall Foundation, said that in terms of the long-term sustainability of political support, both of them face great resistance. For domestic political purposes, they need each other.

　　German-American relations are frequently questioned.

　　Although Biden called virtue "in step with all aspects", many analysts believe that there are many practical contradictions between virtues on many issues. CNN said that in the two countries, the voice against providing military assistance to Kiev is becoming louder and louder. Therefore, although the two sides announced that they would provide main battle tanks to Ukraine, they still shirked the relevant details. Not long ago, Sullivan, Assistant to the President of the United States for National Security Affairs, claimed that the United States agreed to deliver M1 main battle tanks to Ukraine under the "hard pressure" of Germany. The American statement angered Germany. The german government immediately refuted the us statement. At the Munich security conference not long ago, German Defense Minister pistorius complained without name that "some countries prefer to hide behind Germany" when it comes to tank aid.

　　The explosion of the Russian-European "Beixi" natural gas pipeline in September last year is another point of disagreement between the United States and Germany. Before Scholz’s visit to the United States, a number of German lawmakers demanded that Scholz should take tough words against the United States when meeting Biden. However, judging from the public information, the talks did not mention the "Beixi" incident. "Russia Today" TV station said that the German government remained silent half a year after the incident. "The vassal position of the United States does not allow Berlin to talk about who is behind the scenes, and Germany’s foreign policy is completely locked in the track of Washington", which will make "Germany’s future into a dead end".

　　In addition, Biden signed the "Inflation Reduction Act" last year, and its protectionist provisions dealt a serious blow to the automobile industry in Germany and other European countries. Agence France-Presse said that Germany-US relations are relatively close (closer than France-US relations) because of its heavy dependence on NATO and US military protection. But in fact, relations between the two countries have fluctuated recently. For example, the US Inflation Reduction Act heavily subsidized the green industry, which triggered a strong rebound in Germany, but was ignored by Washington.

　　Before the talks, White House officials said that the China issue was also one of the topics of the talks. However, during this visit, Scholz avoided the topic of China. "Deutsche Welle" said that Germany is still waiting to see that China is Germany’s most important trading partner, and the idea of losing business in China will "cause German manufacturers to worry about their survival".

　　"Big Brother is back."

　　Tsargrad TV station in Russia said that at present, the political and military prestige of the West is in jeopardy, and the Western people are increasingly dissatisfied with the government’s practice of arching fire. Due to lack of confidence in France, Britain’s economic situation is difficult and it is no longer a member of the European Union. The United States hopes that Germany will play a key role in mobilizing the European Union against Russia and China. According to the report, judging from the brief press release issued by the two sides after the talks, Scholz showed its "loyalty to Washington as a vassal country. Americans know how to treat weak politicians and obedient countries. "

　　"Big Brother is back", the cover article of the latest issue of German "Star" magazine reported on this topic. For Scholz, "Fortunately, there is Biden — — We can count on the United States again in the conflicts with Russia and China. ".

　　Volodin, chairman of the Russian State Duma (lower house of parliament), wrote on social media on the same day, according to a report by RIA Novosti on the 5th: "The United States once again shows that its basic policy principle is to use other countries to realize its own interests. The United States forced European countries to support the Kiev regime at the expense of their citizens’ welfare, but their own expenses were much less than those of other countries. " He said that the United States spent only 0.37% of its GDP on supporting Ukraine, while Poland spent 2.1% of its GDP. In addition, EU countries have paid an extra price for anti-Russian sanctions, which has affected the national economy. The loss of energy in European countries is about 570 billion euros, and the loss in Germany accounts for 7.2% of GDP.

　　Man made glass more than 5000 years ago. Archaeological evidence shows that in Egypt and Mesopotamia in 3000 BC, people have made some small handicrafts such as amulets and beads with glass.

　　By around 1500 BC, people’s skills in making glass were becoming more and more mature, and the first glass container appeared in human history. The ancient Egyptians also mastered the technology of coloring glass. They know that adding copper powder to glass can make red glass, adding cobalt powder can make blue glass, and adding tin powder can make white glass … These colored glasses are used by some unscrupulous businessmen to pretend to be jewelry, deceiving many people.

　　In the 1st century BC, Syrians invented the technology of blowing glass. With this technology, making glass becomes simple, fast and cheap. Since then, the glass industry has flourished in the Roman Empire and quickly spread to other countries under the rule of the Roman Empire.

　　Around the 1st century A.D., the Romans discovered that adding a proper amount of manganese dioxide to glass could make colorless glass, so they began to make windows out of glass and install them on buildings. Although the optical performance of glass at that time was very poor, glass windows were still "standard" for buildings in Rome, Pompeii and other places.

　　In the 8th century, Venice concentrated a large number of glass workers and became the glass manufacturing center at that time. Later, with the progress of science and art, people "played" more tricks, such as dyeing paint on glass and drawing colorful patterns. Many churches we see now have stained glass windows, which is the architectural style left over at that time.

　　In the mid-15th century, a glass worker in Venice invented a new type of super transparent glass. Soon, this new type of glass was used to make telescopes, thermometers, flasks, microscopes and other scientific instruments, which led to many important scientific discoveries.

　　Around the 18th century, the glass manufacturing center in Europe moved from Venice to Britain. At that time, the output of British glass factories was very high. At one time, the British government would levy taxes based on the number of windows in each house, on the grounds that wealthy families would install more windows, and of course they should pay more taxes. However, "there are policies above and countermeasures below", and many families simply blocked the windows in order to avoid paying taxes-this story shows that the use of glass was quite common in Britain at that time.

　　Since the industrial revolution, steel and glass have become important building materials for modern architecture. In 1851, Britain built a "Crystal Palace", which only used steel and glass. This miraculous building was also the exhibition hall of the first World Expo in London. In 1950s, a German architect innovatively covered the facade of the building with a layer of glass, which made the appearance of the building look unprecedented. This innovative design can be successful, on the one hand, because there is a reinforced frame inside the modern building, and the facade does not need to bear the weight of the whole building; On the other hand, because the strength of glass has become higher. So many skyscrapers we see now have glass facades.

　　Nowadays, scientists and engineers have developed a variety of glasses, which have important uses in many fields. For example, there is a kind of glass that can quickly transmit network information, that is, optical cable, which is filled with thousands of glasses as thin as hair, in which communication signals shuttle in the form of light and quickly transmit information to all parts of the world.

　　Sand and glass

　　The main component of glass is silica, that is, Shi Ying, which is one of the most common minerals on the earth. The sand that can be seen everywhere is actually a small particle in Shi Ying. When Shi Ying is heated to 1400℃, it will melt, then become soft and become a transparent, viscous liquid-then it will be cooled and shaped, and then the glass will be finished.

　　How did sand become glass?

　　On the atomic scale, silicon dioxide is composed of silicon atoms and oxygen atoms, and they are arranged in order in Shi Ying. For example, a group of silicon atoms and oxygen atoms are neatly arranged to form a "queue" with specific arrangement rules, and the whole "queue" is Shi Ying particles. A structure like this, which consists of a large number of microscopic substance units (such as atoms and ions) arranged in an orderly manner according to certain rules, is called a crystal.

　　After Shi Ying melted, its internal crystal structure was destroyed, or the original "queue" was disrupted, and silicon atoms and oxygen atoms began to "run" freely, making Shi Ying change from solid to liquid. Of course, if the liquid Shi Ying can be cooled quickly, the crystal structure will be re-formed, just like the silicon atoms and oxygen atoms that "run" at will "stand" in the original position in the queue again.

　　However, if the cooling speed is too fast, so that silicon atoms and oxygen atoms can’t return to their original positions, then they can only be condensed in their current positions. Therefore, the final glass is like a snapshot of liquid Shi Ying. Scientists have a special name for this state of solid, called "amorphous solid", which means that this kind of solid is different from crystal, and there is no orderly arrangement rule in its internal structure.

　　Why is glass transparent?

　　We can’t go straight through the glass, but our eyes can see the objects on the other side through the glass. Why?

　　We can see an object because the light is reflected or scattered after it reaches this object, which makes some light enter our eyes and let us see the shape and color of the object. Only a part of light energy is received by our eyes, and the rest is absorbed or intercepted by objects.

　　How much light an object can intercept depends on the kind of molecules or atoms that make it up.

　　Most of the atoms in the glass don’t intercept light, and almost all the light that reaches the glass can be received by the eyes (glass can intercept ultraviolet light, but our eyes can’t see ultraviolet light). In addition, glass is not crystal, and there is no edge edge edge of crystal structure inside, so it will not scatter light. So, when the light reaches the glass, it will go straight through without changing its direction.

　　However, if a piece of glass is slightly thicker in some places, the propagation path of light will be bent, which is the working principle of a prism.

This article is from Science Illustrated.

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BMW i4 stands out with its unique front face design and dynamic lines. Its air intake grille adopts a closed design, which shows its pure electric identity without losing the iconic characteristics of the BMW family. On the whole, the exterior style of BMW i4 is both sporty and scientific, which is impressive.

The length, width and height of BMW i4 are 4785mm, 1852mm and 1455mm respectively, and the wheelbase reaches 2856mm. The side lines of the car body are smooth and matched with 18-inch rims, in which the front wheel tyre size is 245/45 R18 and the rear wheel tyre size is 255/45 R18, which further enhances the sense of movement and handling performance of the car.

The interior style of BMW i4 is full of modern technology and luxury atmosphere. The center console is equipped with a 14.9-inch high-definition touch screen, which integrates multimedia system, navigation, telephone and air-conditioning voice recognition control system, making it easy to operate. The steering wheel is made of leather, which feels comfortable and supports manual adjustment up, down and forward to meet the needs of different drivers. There are multiple USB and Type-C interfaces in the car, two in the front row and two in the back row. At the same time, the front row is also equipped with wireless mobile phone charging function, which provides convenience for passengers. In terms of seats, both the driver’s and driver’s seats support multi-directional adjustment, including front and rear, backrest, height, leg rest and lumbar support, and the front seats have heating function. The seat material of BMW i4 is rich, and you can choose imitation leather, genuine leather or fabric/suede materials to meet the individual needs of different consumers. In addition, the driver’s seat also has an electric seat memory function, which improves the driving experience. The rear seats support proportional tilting, which further enhances the practicability of the vehicle.

BMW i4 is equipped with a high-performance motor with a maximum power of 250 kW and a maximum torque of 430 Nm, which provides excellent power performance for drivers.

According to the owner’s evaluation, the design of BMW i4 is really impressive. He said: "The configuration parameters of Series I’s 3, 5 and X3 are almost the same, except that the shell has been changed. I want to buy I4 for more than 100,000 yuan. Of course, it is still imported, and there is no need to do such a thing as buying it home. At first glance, the big nostrils are not mediocre. When I drive out, people are guessing at 600,000. I am sorry. " This design and personalized configuration make the BMW i4 a unique model, which not only satisfies the owner’s pursuit of face value, but also brings full pride.

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BMW i4 adopts a unique front face design, and its kidney-shaped air intake grille is endowed with new life, which combines the futuristic feeling of electric vehicles with BMW’s traditional aesthetics. The enclosed design of the grille not only shows its status as an electric vehicle, but also effectively reduces the air resistance and improves the energy efficiency of the vehicle. The body lines are smooth, and the waistline on the side of the body extends from the front fender to the rear of the car, creating a dynamic visual effect. The rear part is mainly based on concise design language, and the slender LED taillight group echoes the light group at the front, and at the same time enhances the overall recognition of the vehicle. The exterior design of BMW i4 not only embodies the cutting-edge technology of electric vehicles, but also retains the consistent sports style and luxury temperament of BMW brand.

The side lines of BMW i4 are smooth and dynamic, with a body size of 4785 * 1852 * 1455mm and a wheelbase of 2856mm. The front tread is 1601 mm and the rear tread is 1630 mm, which ensures the stability and handling of the vehicle at high speed. In addition, it is equipped with 18-inch wheels with 245/45 R18 front tires and 255/45 R18 rear tires, which further enhances the vehicle’s grip and driving experience.

The interior design of BMW i4 shows the perfect combination of luxury and technology. The center console is equipped with a 14.9-inch super-large touch screen, which is easy to operate and has excellent display effect. Drivers can use the voice recognition control system to easily control the multimedia system, navigation, telephone and air conditioning, which greatly improves the convenience and comfort of driving. The steering wheel is made of high-quality leather, which provides a good grip and supports manual adjustment up and down and back and forth to meet the needs of different drivers. In addition, the front row is also equipped with a mobile phone wireless charging function, which is convenient for drivers to charge their mobile phones at any time. In terms of seats, BMW i4 offers a variety of choices, including imitation leather, genuine leather and leather /Alcantara mixed materials. The main and auxiliary seats all support a number of electric adjustments, including front and rear adjustment, backrest adjustment, height adjustment, leg rest adjustment and lumbar support, ensuring the comfort of long-term driving. The front seats also have a heating function, which further enhances the driving experience. The rear seats support proportional reclining, providing more storage space.

The engine of BMW i4 has a maximum power of 210 kW and a maximum torque of 400 Nm, which provides strong power performance for the vehicle.

The owner of car home said that he chose the BMW i4 mainly because of its unique design and personalized style. He thought that the 3, 5 and X3 of the I series were almost the same in configuration parameters, but the shells were different. Therefore, he is willing to spend more than 100,000 yuan to buy the BMW i4 to show its unique charm. In addition, he also pointed out that the BMW i4 is an imported model, and there is no need to change the logo after purchase. He mentioned that the design of BMW i4′ s big nostrils makes the vehicle look extraordinary. When he drives this car, people always guess that its price is around 600,000, which makes him feel a little embarrassed.