Fueling up your car with gasoline is a routine — a monotonous activity that car owners do with such regularity, it becomes something that is done without any thought whatsoever. In fact, the only thinking or recognition done at the fuel pump is choosing a price that is right. That is, whatever gas station is offering the lowest rates is the one consumers choose.
Most consumers notice that there are three grades of octane (regular, mid-range, high-range) and generally choose regular because it is invariably cheaper than the other two octane ratings. Understanding the differences between the three grades is usually not even a factor.
In reality, most consumers have no idea what octane ratings represent or which one is beneficial for a car.
Octane rating refers to the automatic ignition of gasoline in relation to engine ignition. The three different ratings of octane refer to higher composition percentages of materials used to create the gasoline.
What is the importance of this? It relates to the problem of knocking in an engine. Per wiki, knocking occurs when the air-fuel mixture autoignites all at once (or sometimes perhaps when the flame front goes supersonic because of early ignition timing), before the flame front from spark plug ignition can reach it.
Excessive knocking will eventually damage a cars engine. When one hears knocking, it is time to make a switch in fuel. Should one switch to a higher octane fuel if knocking is not present? Not according to the Federal Trade Commission (FTC).
According to the FTC, using a higher octane gasoline than your owners manual recommends offers absolutely no benefit. It wont make your car run better or perform better, get better mileage or run cleaner..
Surely there must be some benefit to a higher Octane rating. So when does the FTC recommend switching to a higher octane rating? Per Federal Trade Commission recommendations, The only time you might want to switch to a higher octane rating is when your engine knocks when you use oner manual recommended fuel.
Unless your engine is knocking, it is a complete waste of money. Pretty explicit words! These words are also fairly accurate.
There is a difference between the octane ratings other than price, but the differences only come into play if one is utilizing higher octane to reduce engine knocking. If one is using a higher octane level to achieve some mythical concept of higher performance in their car, then they may be in for a rude awakening.
Using a higher octane level of fuel at a point when it is not necessary can ultimately damage the cars engine. No one in their right mind would deliberately and willfully damage their cars engine, yet, this is what people do all the time when they employ the use of higher octane fuel at an inappropriate time.
Also, using higher octane fuel when it is not necessary is a money drain. All it is is paying extra money per gallon for gasoline that is no different than regular octane in any way except for having a negative effect on the car.
Bottom line: stick with regular octane!