What you do not know about the gasoline?
During last summer time back to China, I found out at gas stations gasoline were labelled as different numbers, such as #92, #93, #95, and #97. As far as I know, in the past several years most peo- ple were using #93 and #97, but recently government tries to encourage public using #92 and #95. And then I was curious about the following questions: What do these numbers represent? Which number is the best choice for divers? And why does government encourage public purchasing spe- cific numbered gasoline?
I have asked some people whether they know the meaning of different numbered gasoline, most of them told me the higher number represents the purer gasoline. However according to “Urban Trans- port And the Environment” article, the number has no relationship with gasoline’s purity, it only refers to the amount of octane in the gasoline. The presence of Octane can reduce the explosion possibility. And the higher octane rating is, the less likely explode will occur. This phenomenon is due to octane burns slowly with its long hydrocarbon chain. Based on thermodynamics and engine efficiency, different engines have various compression rations. Normally the lower compression ratio a vehicle has, the smaller number of gasoline it should use, and when a high numbered gasoline is used by a low compression ratio vehicle , it could cause incomplete combustion and can be harmful for the engine.
Nowadays governments are encouraging public to use #92 gasoline instead of #93. This is because #92 is more environmental friendly than #93. As being reported, sulfur content limit in #92 has been reduced from 50 mg per kilogram to 10 mg per kilogram compared with #93. When using gasoline #92 instead of #93, it becomes better for environment.
Based on the information above, the gasoline which is being used recently becomes more and more environmental friendly. And a higher numbered gasoline does not guarantee it would be better for engine, it only represents the more octane existing in gasoline.
Reference:
The difference between #92 gasoline and #93 http://www.autohome.com.cn/dealer/201405/12201588.html(assessed Oct 2nd 2016). http://bbs.pcauto.com.cn/topic-5089619.html
Octane Rating
https://en.wikipedia.org/wiki/Octane_rating(assessed Oct 2nd 2016).
What does 92, 95 and 98 on petrol mean? https://onthegreenwagon.wordpress.com/2014/10/14/what-does-92-95-and-98-on-petrol-means/ (assessed Oct 2nd 2016).
