Thursday 20 October 2011

Regular or premium?

Today's cars can often run on both regular and premium fuel. Some manufacturers recommend that their cars only use fuel with an octane level of 95 or higher. Note that recommend does not mean "must".

Most modern cars have sensors which can detect the type of fuel you use and will adjust the settings in the car's computer to control how your car runs on that particular type of fuel.

Using premium fuel decreases the chances of an engine knocking (pinging). To my ears, knocking sounds like marbles being rattled around in a plastic box. You can try to make your car knock by accelerating lightly uphill in a higher gear (3rd, 4th, 5th or 6th). Have the windows up and any other noisey accessories switched off to help listen out for it.

Is knocking bad for your engine? YES!!


Over time, knocking can damage engine components which can result in an engine losing compression, and thus performance and economy.

I use 98 octane fuel (100 until it became unavailable) in my car because it operates and performs much better than it would using a lower octane fuel. The computer in my car has also been reprogrammed to run at peak performance and efficiency using high octane fuel.

My car can run on lower octane fuel if 98 is not available (91 octane), but I have to be careful with how I drive (not putting the pedal to the metal) and under what weather conditions and engine loads I subject my car to. 

In Melbourne, summer temperatures can climb to over 40 degrees celsius (104 degree F), I will use 98 octane fuel in summer regardless if the car is a Corolla or a Ferrari, as it helps to reduce heat, stress and demands on engines to perform at peak efficiency and performance.

High octane fuel is guaranteed to make your car perform at its best, especially in hot climates.

In winter, using premium fuel does not matter as much due to the lower temperatures. Some cars which normally run high octane can run a lower octane during winter.

Since the price of fuel in 2011 is much higher than it was in 2000, I can't justify paying for higher prices only to get a lower octane fuel, especially if premium is only a few cents more. At the time of writing this, the difference between a litre of regular and premium was 15 cents a litre, so for every 10 litres of fuel, it costs $1.50 more to run premium.

I support using premium fuel because not only does my car run at its best, it also contains detergents and solvents which clean and protect the car's fuel tank, fuel lines, fuel pump and injectors.

Many years ago, I ran my car on regular 91 unleaded. However, after removing a filter and cutting it open to examine the contents, I was horrified with what I saw. This also explained the rattling noise from my car at the time whenever I jumped on the gas pedal.  

I still get the odd rattle today but I attribute that to poor quality fuel. I have noticed that fuel quality isn't as consistent as it once was due to lower profit margins made by petrol station operators.

Some operators may cut costs and corners by diluting fuel with other chemicals, so buy fuel from operators who are busy and turnover large quantities to reduce the risk of contamination or damage to your car's fuel system.

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