Tips from Used Car Advisor

Car Advisor Tamotsu Todoroki

Hi, this is Tamotsu Todoroki. I am a car advisor of
I write an online column every week to take care of your vehicle. My column is all about something useful and practical for your vehicle. Please have a look once to keep your car in good condition.


Should I Choose High-Octane Gasoline? - Vol.61

Car owners and car lovers are always concerned about the type of gasoline that will increase the efficiency of the car. The owners are always concerned about the fact whether to use high octane gasoline or not? Before understanding whether to use high octane gasoline, we will try to know what gasoline is.

Gasoline is most commonly used as a fuel for spark ignition type engines. Gasoline is a mixture of hydrocarbons. Gasoline is sprayed to the engine along with the mixture of air. When the engine heats it turns the gasoline into vapor. This vapor helps to create ignition with the help of spark plug this burns the mixture. Additional additives are mixed with the gasoline to increase the quality of the fuel. When the ignition occurs before time, there is a problem with the mixture of the gasoline. This damages the engine and engine makes some knocking noises. Depending on the knocking sound of the engine, the quality of the gasoline is decided. The gasoline quality is measured in octane number.

Octane word originated from iso-octane, which is a hydrocarbon in liquid form, which is used to measure the quality of gasoline. Therefore, the gasoline with 90% iso-octane and 10% N-heptane have anti knocking quality of 90 octane. Commonly gasoline has anti knocking quality of 90 octane. As the number of octane increases, the burning quality is decreased. Hence, the gasoline with less octane value burns faster than gasoline with high octane value.

Therefore, according to the octane value the gasoline is classified as mid grade, regular grade, and high grade gasoline.
·  The octane value or anti knocking rating of gasoline with mid octane value is 88 and it can be less than or nearly equal to 90.
·  Regular grade gasoline has octane value of about 85. It could reach up to 88.
·  High grade octane value is equal to 90.

People are generally confused which kind of gasoline should be used in their automobiles. The design and efficiency of the engine decides what kind of gasoline to be used. Higher octane value does not mean that it is suitable to all kinds of vehicles. The high octane value makes the fuel to combust slowly. Octane value of engine can be decided depending on the compression ratio of the engine. If the compression ratio of the engine is more than high octane gasoline is required.

If we use low octane gasoline with high compression engine, then it can damage the engine. Knocking and banging noises are heard while driving, which indicates burning of gasoline beforehand. This leads to serious damage to the engine. The manual book which comes along with the car, will indicate the engine mechanism and what kind of gasoline to be used.

Therefore, use of high octane gasoline in all kind of automobiles is not advisable. The high octane gasoline is used to avoid the knocking sounds in the engine. If we are travelling at high altitude places, then using high octane gasoline is not advisable. This will demand more cost. The cars with good engine power, who has high compression and engine is under high pressure, requires high octane gasoline.

If the car has normal engine power and if we try to use high octane gasoline in such engine, then the fuel will not burn properly in such kind of car. This will increase the incident of knocking. In engines with less power and high octane gasoline, there are chances of carbon deposition in the engine, which will lead to engine clogging. This in turn will decrease the capacity of engine to work and gives low mileage. In long run engines will get damaged permanently. This will cost a fortune.

Therefore, depending on the quality of the engine octane value of gasoline should be decided. With high power engine, premium quality gasoline is suitable and likewise with low or common engine power, low octane gasoline is suitable.