Dubai: Drive into any petrol station for a refill and probably the only question the attendant will ask: “Special or Super?”. You will pick one or the other without a moment’s thought and drive away as soon as the payment is done.
There are two types or grades of petrol available in the UAE - Special at 95 octane and Super at 98 octane. Car enthusiasts have long butted heads in debates over which of the two allow their car to deliver a better performance.
Many argue that petrol with a higher octane value increases power in vehicles, deliver less pollution and help to maintain a cleaner engine. Others counter that there is barely any difference in car performance and that using a higher octane value fuel is actually detrimental to the engine.
Petrol companies say that while all fuels contain cleaning additives, those with high octane levels contain more or better detergents to keep the injectors clean. In addition they also claim that Super fuels are a few percentage points denser which allows slightly more power per litre in the vehicle.
So, should drivers switch to using high octane Super fuels in their cars? According to Bill Carter, head of valuations and research, Autodata, it is only high performance cars that require Super petrols. “There is no advantage in using a higher grade of petrol than is recommended by the car manufacturer,” said Carter. “The additional cost far outweighs any perceived increase in performance.
“In fact, it may end up increasing the carbon deposit build up in the combustion chamber of the engine. This would result in having to have the engine de-coked earlier than one would expect.”
Using a high octane fuel when your car was made to run on a lower octane fuel has been found to be harmful. It should also be noted that using a low octane fuel when your car requires a higher version is just as damaging and will lead to an abnormal combustion of the air-fuel mixture in the cylinder. It will cause a phenomena known as “knocking” to occur.
When a spark initiates combustion in a spark-ignition internal combustion engine, the flame front should fan out from the spark plug and travel across the combustion chamber rapidly and smoothly. Knocking occurs if the last part of the air-fuel mixture ignites spontaneously before the flame front arrives and that leads to a sudden jump in the pressure in the cylinder which creates a “knocking” or “pinging” sound.
How do you know what type of fuel is right? The easiest way to find out is check the owner’s manual. Another way would be by listening carefully to the sound of your engine. If there is no “knocking” sound then you are using the right grade.
It is also advisable to select a good fuel system cleaner for your car. According to Carter, there is a benefit in drivers using a fuel system cleaner, especially if they do not service their cars regularly.
“The fuel system can get a build-up of deposits in fuel lines and injectors; the effect on injectors is the most critical as this will control the fuel spray pattern and quantity of fuel entering the combustion process,” Carter added. “This, in turn, has a detrimental effect on fuel consumption, performance and emissions.”
Popular fuel additives help restore lost power, improve performance and fuel economy. They also keep the engine clean by clearing up deposits. For drivers that have their car serviced, these cleaners are often offered as part of the normal routine.