dexos oil change interval Read more In fact, value has its objective existence form and its subjective reflection form. Subjective value can be divided into two specific forms: values and emotions. Among them, values are people's understanding of absolute value, or people's understanding of value absoluteness. Emotion is the perception of relative value, or the relative understanding of value. Values (or emotional) and the value of relationship in essence is the relationship of subjective and objective: on the one hand, the objective value decision and restricts the subjective value, subjective value is to reflect the objective value, based on the objective value, and around the objective value fluctuates up and down; On the other hand, subjective value has certain relative independence, and has a certain reaction to objective value, which can induce, strengthen or restrict the objective value. The importance of gasoline was not recognized in the 19th century, when it was used in a great deal of kerosene. The oil refining then relied on simple distillation processes to separate the different components of the oil from the boiling point. The boiling point of the kerosene component is higher, and the use of safety when lighting lamps becomes the main product of crude oil refining, while gasoline and other components are often burned as fuel. By the mid - to late 19th century, the successful use of gasoline engines in 1886, in 1886, the gasoline engine was successfully used as a driving force, thus the importance of gasoline increased. But using distillation, only 20% of the gasoline can be extracted from crude oil. In 1911, the standard oil company have solved the problem of low gasoline yield, by William burton and Robert hamm forest thermal cracking process of the invention, the heavy quality heating gas oil cracking of light gasoline fractions, such as to overall improve the gasoline yield, thermal cracking process in 1913 won the patent license in the United States. The subsequent catalytic cracking process has further improved the gasoline yield and octane value.