Suitable is the best way to talk about the purchase and use of engine oil

　　[Technology], also known as the "blood" of a car, I think anyone who drives a car will know something about it. Especially with the increasing popularity of automobiles, the choice of vehicles has become more and more abundant and diversified, and everyone has paid more attention to engine oil. Today, we will talk with Castrol engineers about how to choose and use engine oil and some basic problems about engine oil. As for how to choose between mineral oil, partially synthetic oil and fully synthetic oil, the answer given by the engineer is "there is no best, only the most suitable".

　　Let me briefly introduce two Castrol engineers who accepted our conversation today. They are Mr. Liu Jianhao (left), technical manager of Castrol vehicle oil products (China), and Mr. Huo Haitao (right), technical support engineer of Castrol.

● What is engine oil? What is the function of engine oil?

　　Let’s start with the most basic question. What is engine oil? Engine oil, that is, lubricating oil, plays a role in lubricating, cleaning, cooling, sealing, reducing wear, damping and buffering, and preventing rust and corrosion. For the basic introduction of engine oil, please click here.

● What are synthetic oil and mineral oil?

　　At present, engine oils on the market are divided into mineral oil, partially synthetic oil (commonly known as semi-synthetic) and fully synthetic oil according to their base oils. Mineral oil is directly refined from crude oil. The oil that has not been artificially added and changed is called mineral oil, and the synthetic oil is made by artificial methods, including cracking and polymerization. If the base oil used to produce engine oil is all made of this kind of synthetic oil, it will be called synthetic engine oil.

　　As for semi-synthesis, the more accurate statement should be partial synthesis. Different "semi-synthetic" engine oil products have different proportions of mineral oil and synthetic oil, not all of which are 50:50, so it is not very accurate to say semi-synthesis. From the perspective of engine oil, it is more willing to call it partial synthesis.

　　In terms of performance, the first is low-temperature fluidity. Even mineral oil and synthetic oil of the same brand have different fluidity at low temperature. The fluidity of synthetic oil is the best, which is helpful for the cold start of vehicles and can also reduce fuel consumption to a certain extent. The second is the high temperature resistance of oil, which has better protection effect for engines that pay attention to high speed performance.

　　The third is volatility. Because all synthetic oils are synthetic, their volatility will be lower than that of mineral oil. Therefore, when in use, people will think that all synthetic oils are more durable, and there will be relatively few cases of high oil consumption. Of course, about the oil consumption, it is also related to the design of the engine.

　　Generally speaking, the engine oil consumption of European cars is indeed higher than that of Japanese cars, which is mainly due to the difference in design. For oil manufacturers, there is no saying which product can completely solve this situation, mainly depending on the design of vehicle manufacturers. Of course, if you think that your car has excessive oil consumption, you can consider trying synthetic oil with a slightly higher viscosity, which may improve to some extent, but it can’t be completely cured.

　　In this regard, China’s national standard "Test Method for Automobile Engine Performance GB/T19055-2003" clearly stipulates that "the rated speed and full-load engine oil/fuel consumption ratio shall not exceed 0.3%". Generally speaking, assuming that the fuel consumption per 100 kilometers of the car is 10L (subject to the published data), the standard of oil consumption per 1000 kilometers is 0.3L, which is lower than this value, which is "reasonable" according to the national standard. Although from our point of view, this value seems a bit too broad, but there is no way, the current implementation standard is this, whether it is reasonable or not, a certain enterprise can only be judged by the relevant competent authorities.

　　After all, as far as the phenomenon of large oil consumption is concerned, the main reason is related to engine design, and choosing different oil can only play an auxiliary role. More importantly, from the perspective of engine oil manufacturers, it is a phenomenon that the oil consumption is high. As for the reasons for "consumption", it is diversified, and this is not something that engine oil manufacturers can judge, but more depends on what the vehicle manufacturers say.

● How do consumers choose engine oil? Is synthetic oil the best?

　　The principle of buying engine oil is "there is no best engine oil, only the most suitable engine oil". First, it is recommended that you use the specifications recommended by the vehicle manufacturer. When you buy engine oil, you must choose the corresponding specifications, and at the same time check whether you have passed the corresponding certification, such as environmental protection grades such as SL, SM and SN and various performance grades. In short, from the perspective of Castrol, we suggest that you choose the corresponding viscosity and grade according to the model recommended by the manufacturer, and also according to your own economic strength.

　　If you care about the price, drive more and change the oil frequently, you can use mineral oil and some synthetic oil, but if you drive less and change the oil only once a year, it is recommended to use a better, fully synthetic oil. As for viscosity grade, for example, some European and Japanese manufacturers, in recent years, for the sake of environmental protection and fuel saving, will recommend the use of low viscosity engine oil such as 5W-20, as long as you follow the manufacturer’s recommendation. Of course, if there is no special provision from the manufacturer, you can choose the engine oil with reference to the vehicle environment. Generally speaking, the common engine oils such as 0W-40, 5W-30 and 5W-40 on the market have strong applicability, which can be suitable for the climate in most parts of China and the use of most vehicles.

　　For old cars that have been driven for more than 10 years and the mileage exceeds 200,000 kilometers or even 300,000 kilometers, we can consider using high-viscosity oils such as 15W-40 and 15W-50. The advantages of this kind of engine oil are that it will be better sealed, it will be easier to maintain oil pressure and reduce engine oil consumption, and most of these oils are mineral oil. If the old car uses low-viscosity engine oil, it may lead to insufficient oil pressure, which can not meet the lubrication needs of the engine and aggravate wear, which is harmful and not beneficial. Therefore, from the point of purchase recommendation, the choice of engine oil is not as expensive as possible, and synthetic engine oil is not a "panacea", but should pay attention to the principle of application, which is called."The right one is the best."After all, everyone’s economic strength and car use concept are different, and it is sometimes an unnecessary waste to think that it is good and expensive. Of course, for base oil, it must be synthetic than mineral.

● How to judge the oil attenuation and what is the reasonable oil change mileage?

　　Castrol engineers said that from the test and research of oil products, the viscosity change, water content, total acid value and total alkali value of oil products are all the basis for considering whether oil products should be replaced, but these are all based on the analysis of oil products in the laboratory. From the owner’s point of view, there is basically no way to detect it from the use experience of the vehicle. Therefore, from the perspective of oil manufacturers, we still follow the recommendation of oil change mileage of vehicle manufacturers, and this data has been demonstrated by manufacturers based on a large number of experimental results.

　　In principle, the oil change cycle of synthetic engine oil is definitely longer than that of mineral oil.Generally, the oil change cycle of mineral oil is about 5,000 kilometers, and the total synthetic oil can be used for about 7,500-10,000 kilometers.. In terms of time, whether it is mineral oil or synthetic engine oil, it should not exceed one year. Of course, the above situation is mainly aimed at the China market. In Europe, the oil change cycle of some cars is really long, ranging from 15,000 km to 20,000 km, and even 30,000 km. This is mainly because the local fuel quality is good, the impurities and sulfur content are low, the local air quality is good, and it is related to the road conditions. The traffic jam cannot be serious, and the oil needed is also a long-term engine oil product, but this is not suitable for the current domestic situation. Of course, except for some European countries, the oil change mileage in most places, especially the United States, Canada and Japan, is not particularly long, basically around 5000-10000 kilometers, which is similar to that in our country.