What are the aspects of the performance of engine oil? Engine oil plays the role of lubrication, sealing, cooling, and rust prevention in the engine. Therefore, engine oil is a very complex mixture, and in a motor oil, there may be 2~3 types of base oil alone. And additives are even more varied: detergents, dispersants, extreme pressure additives, antioxidants, viscosity index modifiers......
It is precisely because the composition of engine oil is very complex, so for ordinary car owners, it is obviously far beyond their own cognition. The grade of engine oil that ordinary consumers know may be the "level information of engine oil", such as SP grade of API, C3 grade of ACEA, and so on. To put it simply: you can know how good a motor oil is by reading the "grade information" of the engine oil.
So what do these different levels mean, and what is the performance gap between them? Because the article is too long, in order to make it easier to digest and understand, we plan to do a comprehensive interpretation in three parts. First of all, the requirements of professional organizations for engine oil are roughly divided into 10 capabilities. They are:
Wear anti-wear lubrication protection
Sluge's ability to inhibit sludge formation
Deposit's ability to inhibit sediment formation
Oxidative Thickening 抗氧化变稠
Fuel Economy 燃油经济性
Aftertreatment compatibility 尾气后处理设备兼容性
Soot thickening 抑制积碳生成能力
LSPI protection 预防低速早燃
Corrosion (Diesel Engine Oil Only)
Bore Protection 抵御气缸壁磨损抛光的能力（柴油机油专属项目）
In today's teaching, we will disassemble the first 2 knowledge points. At the end of the article, examples are used to guide everyone how to understand the corresponding level information.
Wear anti-wear lubrication protection capability
The essence of engine oil is lubricating oil, and the most basic role of lubricating oil is lubrication. The door lock at home does not rotate flexibly, drop a few drops of oil into it, and it will rotate freely again, which is lubrication. The essence of lubrication is to "isolate the metal from direct dry friction of the metal".
When the engine is running, the presence of organic oil forms an "oil film" on the metal surface, so the metal and the metal cannot come into direct contact, so the "dry friction" is avoided. The longer the oil film is maintained on the metal surface, and the stronger the film itself, the better the lubrication protection effect of the oil.
At present, the anti-wear additives of mainstream engine oils are mainly zinc dialkyl dithiophosphate (ZDP). Of course, if the base oil itself has good enough lubricating properties, then the demand for additives is relatively low. For example, ester oils are inherently very good oil film properties.
Sluge's ability to suppress sludge formation
After the oil has been used for a long time, some of the gum in the oil will gradually be separated from the oil, and the moisture in the oil will also react with some of the oil, resulting in an emulsification effect. The emulsified product also belongs to oil sludge. In addition, the gum contained in gasoline/diesel (which is difficult to burn sufficiently) can also promote the production of more sludge in the oil.
Because it looks like disgusting sludge, it gets the name "oil sludge". Sludge can flow with the oil, which can lead to danger: if there is a lot of sludge in the oil, it can clog the oil collector or oil filter over time, blocking the flow of oil and causing damage to the engine due to lack of lubrication.
Therefore, we want the oil to have the ability to "resist" the formation of oil sludge, which is called "cleanliness". The "cleanliness" of motor oil is mainly achieved by dispersants. Of course, different base oils have different "cleanliness" by themselves. Base oils such as PAO or GTL/CTL/XTL (natural gas, coal, or other carbonaceous substances synthesized by Fischer-Tropsch) have excellent "cleanliness" by themselves, so the demand for dispersants is relatively low.
Instance parsing
Finally, let's take Honeywell V9 engine oil as an example. This is a fully synthetic motor oil mainly formulated with PAO base oil as the main body, and the viscosity label is only 0W-20 optional. This oil was developed by Honeywell for the new Volkswagen Euro VI (China VI) car.
The bottle of Honeywell V9 motor oil is marked with its grade information: API SP/ACEA C5/Volkswagen VW508/509. Next, we use <路博润机油性能参照工具>it for analysis. You can understand it in conjunction with pictures.
It can be seen that the Volkswagen VW508/509 has higher performance requirements than the API SP and ACEA C5 in all aspects. What is more special is the API SP standard, which specifically puts forward special requirements for LSPI protection to prevent low-speed pre-ignition (this knowledge point will be discussed in the following popular science).
The engine oil that meets the Volkswagen VW508/509 standard is commonly known as "Volkswagen Blue Oil", and the "Volkswagen Blue Oil" standard itself requires the base oil type of the engine oil to be PAO, so there is a saying that "Volkswagen Blue Oil has no weak oil". This also confirms that Honeywell V9 engine oil is a high-end product.
今天的科普暂且告一段落，我们下一期将会讲述机油的：Oxidative Thickening抗氧化变稠、Fuel Economy燃油经济性、Aftertreatment compatibility尾气后处理设备兼容性，这三大性能。