First look at the classification of
motor oil, API means American Petroleum Institute. Base oil is divided into 5 categories by API.
We call it mineral oil in categories 1 and 2. The difference between mineral oils in categories 1 and 2 is the difference in sulfur content and the proportion of saturated components. The raw material of mineral oil is the crude oil extracted directly from the ground. These crude oils are processed and refined through distillation, dewaxing, deasphalting and other processes to form these mineral oils.
Category 3 is actually strictly mineral oil, but in general we still call it semi-synthetic
motor oil, because its raw material is still crude oil, but its processing process is more complicated and costly than category 1 and 2 motor oils. Because the raw material used for it is still the crude oil pumped out of the ground, some countries still do not recognize Category 3 motor oil as synthetic motor oil.
There is no controversy about the fourth type of
motor oil is what we usually call fully synthetic motor oil (PAO). The difference between this and mineral oil is that the raw material is not crude oil pumped out of the ground. German scientists invented this kind of motor oil, which is not based on crude oil, but through blending. It turns out that the performance of this formulated oil is even better, and it has been used until now
Category 5
motor oil. Refers to all oils including all synthetic oils of lipids except the above 4 types of motor oils.
To sum up the difference: the synthetic oil component in the base oil is more than 90%, which is fully synthetic
motor oil; the proportion is less than 90% is semi-synthetic
motor oil; if there is no synthetic oil component, it is mineral
motor oil.
Another thing to say is the classification of
motor oil by API. Generally divided into two categories, "S series" represents gasoline
motor oil, "C series" represents diesel motor oil. If there are S and C, it means that this oil is common to gasoline and diesel. S in front means it is mainly used in gasoline engines, and C in front means it is mainly used in diesel engines.
The API also has a service category. The service category has been from "SA" to the highest "SN". Every time a letter is incremented, the performance of this type of oil will be better than the previous one, and there will be more additives used to protect the engine. Therefore, from the perspective of oil performance, anything above SJ grade can be used. If you are too lazy to remember or choose too much, then just remember to buy the SN grade motor oil of big brands directly.
