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The history and evolution of lubricating oil!
Release time:
2025-12-05 17:13
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【Summary Description】
Practical experience has shown that the heat generated by dry friction in a short period of time is sufficient to melt metal, causing damage to machinery and even seizing (many cars with water or oil leaks experience issues such as cylinder pulling and shaft binding, mainly due to this reason).
The term "lubrication" addresses the friction problem in classical mechanics. Today, we have relativity and quantum mechanics, but for thousands of years, life has not been free from the constraints of friction. Therefore, in reality, the origin of lubricating oil is no different from the wheels that can be found everywhere on the roadside; humanity lit this tree of talent at the dawn of civilization.
1. From vegetable oil to mineral oil
As early as the 17th century BC, there are records in ancient Egypt of using olive oil to transport giant stones. By the 14th century BC, humans could even use animal fats to lubricate chariot axles, but due to the demand for food, stable extraction of lubricating substances from plants and animals did not occur until the Middle Ages. The explosion of modern civilization began with the First Industrial Revolution, and the modern concept of lubricating oil was reborn alongside the surge in oil production.
Peter Kalm
In 1747, 31-year-old adventurer Peter Kalm was tasked by the Royal Swedish Academy of Sciences to travel to North America for exploration and bring back crops that would benefit Swedish agriculture. However, the map he drew the following year made him remembered in another way. The place on the map later became known as Oil Creek. In 1859, Edwin L. Drake established the first commercial oil well here. Interestingly, this oil well was destroyed by an open flame more than a month later, and Drake had to rebuild it. In today's view, that was a spark in the history of human civilization.
Edwin L. Drake
Drake's oil well opened the oil era and accelerated the use of mineral oil by humans. However, the products at that time seemed superior but were controversial: untreated crude oil could not exhibit excellent lubrication performance and could not even compare with most animal fat products.
United States, Pennsylvania, Oil Creek
At that time, a German boy preparing to enter Karlsruhe University would become a turning point 26 years later. As the inventor of the first gasoline engine car in a meaningful sense, Karl Benz began the viral expansion of the automotive market. The booming automotive industry also had a booming demand for lubrication. During this stage, solvent-refined base oils became the best choice, and with the active improvements from various manufacturers, mineral oil eventually dominated the world. In fact, during this period, many well-known oil companies were born, such as the familiar Shell, ExxonMobil, Castrol, as well as BP, Motul, and many others.
The first car in a meaningful sense comes from Benz.
At that time, the entire industry lacked sound standards, and designers varied widely in style, much like Su Dongpo and Li Qingzhao. In the process of globalization, the lack of unified standards among manufacturers incurred great costs. Therefore, starting in 1911, the SAE (Society of Automotive Engineers) began to address this issue and published SAE J300. Today, the various grades of lubricating oil we can use to cope with different vehicle types, weather, and regions all started here.
2. How does SAE (Society of Automotive Engineers) classify engine oil?
At that time, the highest working temperature that lubricating oil could withstand was around 100°C, and the viscosity characteristics of lubricating oil decreased as the temperature increased. Excessively high ambient temperatures could cause lubricating oil to become too thin, failing to form an effective oil film to protect components. Therefore, selecting 100°C as the reference temperature for testing the viscosity of lubricating oil has certain reference significance.
How is viscosity tested?
Engineers use viscometers to let lubricating oil flow through specific pipes, measuring the time required for this process. The parameters quantified in this process are called kinematic viscosity. For the average person, this parameter is not easy to understand, and in fact, when the viscosity difference is not significant, the differences in lubricating oil may not be that great, so SAE ultimately classified it.
SAE Classification
The performance of SAE 30 covered the needs of most areas, making it the most widely accepted grade at that time. Lubricating oils with higher or lower viscosity were more often used to handle extreme conditions; for example, racing engines, which operate at higher temperatures, required SAE 40 or SAE 50 lubricating oils.
Before 1930, lubricating oil could only meet the mileage of about 1500 km for cars. The issue of durability prompted manufacturers to accelerate the development of additives. During this stage, engineers discovered that zinc and phosphorus could serve as core anti-wear agents, while calcium and magnesium were key to detergents and acid resistance, etc. Additives greatly extended the lifespan of lubricating oil and were commercialized around 1940, but that was still not enough.
War machines demanded higher standards for engine oil.
During World War I and World War II, the explosion in the number of aircraft raised higher demands for engine speed and load. After the war, these demands were placed on automobiles, with the most obvious manifestation being that the performance of luxury cars could rival that of pre-war racing cars, which also meant that the civilian market's demand for SAE 50 began to increase. Unfortunately, SAE 50 had just enough viscosity at high temperatures to cope with high-performance engines, but became too thick when the ambient temperature dropped. At this point, both engineers and consumers recognized a problem: the existing grading system was insufficient to describe the low-temperature performance of existing engine oil products.
During World War II, the rapid development of the petrochemical industry attached to the plastic industry led engineers to discover the potential of polymer materials: viscosity index improvers could slow down the trend of viscosity decrease in engine oil at elevated temperatures. For example, SAE 30 lubricating oil, after modification, could not only maintain its low-temperature performance but also achieve SAE 50 viscosity in high-temperature environments. To distinguish whether lubricating oil had undergone this treatment, SAE began to implement composite grading for this type of oil in 1952, and with the arrival of winter, "W" appeared.
SAE Classification
SAE 30 lubricating oil, which can meet environments above -10°C, is also equivalent to SAE 20W30. If modified to meet SAE 50 standards, it becomes SAE 20W50. This grading system was quickly accepted by the industry, and the most popular SAE 30 before the war had already transformed into SAE 20W50 after the war.
SAE Classification
Early composite-grade engine oils also had defects: viscosity index improvers could easily oxidize into harmful substances. In light of this fact, the first answer people found was fully synthetic oil, but at that time, its price was often more than three times that of ordinary oil, making it difficult to promote.
3. How has the SAE compliance grading system been improved?
With the popularity of multi-grade oils, SAE realized the limitations of J300: the viscosity properties of multi-grade oils are very different from those of single-grade oils under high temperature and high pressure conditions, and some multi-grade oils are prone to failure at high temperatures. Therefore, between 1970 and 1975, SAE revised J300 and added a 150°C ultra-high temperature test. As for the continuous advancement of lubricant technology, it has also been constantly driving changes in this standard, and the rigorousness of the past allows us to have better foundations today.
Today, SAE J300 defines oils without viscosity enhancers as single-grade oils and defines 6 winter grades and 5 summer grades. The testing methods and units used for these two categories are different, so products like 0W40 and 5W40, which are multi-grade, must pass tests for both grades.
In the summer grade testing, to ensure that the oil has enough reserve to cope with the process of viscosity thinning as the temperature rises, a higher grade is the preferred choice for consumers. However, as mentioned earlier, grades are defined within a certain viscosity range. For example, among the four brands of oil below, although they have the same grade of 0W40 or 5W40, the viscosity of 3M is significantly higher, while brands S and C are comparable. This is somewhat like an exam, where a score of 95-100 is considered A+, but a perfect score of 100 is still somewhat different from 95.
High-temperature oil viscosity performance
If the viscosity is too high in low-temperature environments, it can lead to poor oil flow during cold starts, failing to lubricate components in a timely manner, so a lower viscosity grade is better. As can be seen in the chart, 5W40 has a higher winter grade number, and the viscosity of the four brands is higher than their own 0W40 products. When determining grades, low-temperature flowability also varies; among the fully synthetic products of 0W40 and 5W40, 3M outperforms the other products, while among the semi-synthetic products of 5W40, brand S has a slight advantage.
Low-temperature oil viscosity performance
Before the 1960s, there were no effective standards to control oil quality other than SAE's viscosity grading: there is not just one method to extract paraffin from crude oil, and the components of the refined base oil can vary. For example, some have higher particle solubility and are less likely to produce impurities, while others with more aromatic hydrocarbons are prone to volatilization and oxidation. The American Petroleum Institute (API) thus began to attempt to establish a standard, which is the predecessor of today's API grading system.
4. What is the API (American Petroleum Institute) grading system?
For gasoline engines, API defined oils before 1960 as "SB", but there was a higher grade at that time called "API Service MS". After 1968, these were modified to what we now refer to as "API SC" or "SD".
This standard has been revised and abolished many versions since its inception, and now only the 1996 SJ, 2000 SL, 2004 SM, and the latest and highest requirement SN from 2010 remain.
API grading
Base oils are classified into several categories based on different production processes: solvent-refined base oils actually contain two subcategories with high and low aromatic hydrocarbon content. These base oils have low viscosity coefficients and high sulfur content, making them not environmentally friendly; Group II base oils undergo hydrogenation treatment, making them purer and more stable compared to Group I, with almost no sulfur content; Group III base oils, which are still essentially mineral oils, can compete with high-quality synthetic oils, but they also have many shortcomings.
