Is #95 purer than #92 gasoline?
Gasoline is a transparent liquid, containing a variety of hydrocarbons (mainly composed of C5 ~ C12 aliphatic hydrocarbons and cycloalkanes), with combustibility, evaporation, anti-explosive, stability, safety and corrosive characteristics. One of the automotive gasoline explosion resistance expressed in octane number, the higher the octane number, the better the explosion resistance.
The size of the anti-knock capacity and chemical composition, which has a branched chain of alkanes, as well as olefins, aromatics usually have excellent anti-knock, no chemical foundation of the children's shoes to see these terms are estimated to be a face of confusion, in fact, you do not need to know what they are, as long as you know that they have a strong anti-knock capacity, and commonly known as "iso-octane". Another component of gasoline, n-heptane, is more prone to spontaneous combustion at high temperatures and pressures, resulting in the phenomenon of detonation.
The industry stipulates that the octane number of isooctane is 100, which is good for anti-detonation; the octane number of n-heptane is 0, which is bad for anti-detonation, and the octane number of gasoline is determined by octane number machine. We often say 92 gasoline that its octane number is 92, 95 gasoline octane number is 95.
Another thing to note is that the gasoline anti-detonation ability does not mean that the working ability is strong, the working ability of the gasoline is mainly measured by the calorific value, that is, the gasoline is completely burned to produce heat energy, the greater the calorific value, that is, the stronger the working ability. Then 92 and 95 calorific value is a big difference, in fact, the calorific value of gasoline is usually 40.1-41.8MJ, the calorific value of high grade gasoline is only so high that a drop, almost can be rounded up to negligible.
So in summary, 95 gasoline just contains higher octane than 92 gasoline, with better explosive properties, and there is no such thing as pure or impure oil.
Can you mix two kinds of gasoline?
Through the above, we know that 95 gasoline explosion resistance is higher than 92 gasoline, so 95 gasoline is more used in high compression ratio engine (such as turbocharged engines), while 92 gasoline is more used in the compression ratio is not so high on the engine (such as naturally aspirated engines).
So can the two types of gasoline be mixed? With the current quality and working principle of the engine, it will not be a big problem to mix and add once in a while, but it can't be used for a long time, or it will cause vibration, lack of power, and so on.
The same car with 95 oil will not have any big problem if you use 92 oil occasionally, but if you use it for a long time, it will make the bursts more frequent and even damage the engine.