What is the difference between regular and premium fuel?

What is premium gasoline?

Premium gas is a type of gasoline with a high research octane number (RON) relative to other fuels. In the Philippines, there are multiple levels of premium gasoline. There are those rated at 95 RON, and then there are the 97 RON and up gasoline fuels.

In older cars, premium gasoline can provide added resistance against premature detonation and engine knocking. High-octane fuels are also ideal for high-performance engines that have higher compression ratios.

Some engines, like rotary engines, will always require high-octane gasoline

To be certain as to what fuel to use, always consult your car’s supplied manual. If that isn’t available, you can contact your nearest dealership. For older cars, we suggest turning to car forums dedicated to your specific car model.

What is the difference in octane ratings?

In other parts of the world like Canada and the United States, octane ratings are displayed in AKI or anti-knock index. This figure is the average of RON as well as motor octane number, or MON. As a result, a 97 octane or “super unleaded” in Britain is only equivalent to a 91 octane premium in the US and Canada.

In the Philippines, fuels are labeled with the RON rating only. The lowest RON requirement in the country is set by the Philippine National Standards at 93. This is equivalent to 87.5 AKI “regular” fuels that are sold in North America.

A fuel pump in the U.S. [Photo: Bobak/Wikipedia Commons]

The next level of premium fuel in the Philippines is 95 RON. 97 RON and 99 RON fuels are also sold locally depending on the fuel company.

For those unaware, RON is the standard measurement for the performance of gasoline. It is also the most common octane rating in the world.

The higher the RON, the higher the compression the fuel product can withstand before blowing up. As such, RON is determined by using a test engine with a variable compression ratio, in a controlled condition.

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How about the cost difference?

To get a glimpse of how a gasoline product’s RON rating affects its price, let us refer to this table showing the price range for fuels per RON rating in several cities in the National Capital Region as of this writing.

As you can see from the table above, there is certainly a significant cost difference between regular and premium gas. Do note that the figures are presented in a range as there are variances depending on the fuel company, and the location. In general, however, the price ranges for fuels with higher RON is higher than those with a lower RON rating.

A fuel's octane rating is often indicated on a fuel pump

Why does premium, higher RON rating gas cost more? Well, fuels with higher RON ratings have a higher cost to manufacturers. They require more blending, and also more refining. Apart from these factors, higher octane fuels also have a higher demand.

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Does premium fuel last longer than regular fuel?

There are no additives in premium fuel that can make it last longer than regular fuel. The only benefits that you can get from premium fuel is the higher-octane levels, and the lower chance of engine knocking, and premature detonation.

So how to decide between premium and regular gas for your engine?

As we’ve said, you must first check with your car’s manual if it requires premium fuel or not. Usually, a specific RON or octane rating is indicated so follow that religiously. If you lost your car’s manual for some reason, you can also contact a dealership that’s selling, or has sold your car model.

Do note that cars nowadays are really smart. They can detect the quality and quantity of a fuel mixture and so might detune itself when you put in the wrong fuel. This isn’t particularly bad, but that said, premium doesn’t always mean the best for your engine. If your manual says regular (low octane) use low octane gas only. If it says premium, use premium gas only.

If your car is an older model (less advanced ECUs), do note that putting in the wrong fuel will have larger consequences. Loading up on regular when premium is required for example, will result in engine knock.

As we've said time and time again, learn everything about your car by reading the manual

Is it okay to mix premium and regular fuel?

Mixing low and high octane (RON) fuels will result in a mixture of octane ratings that’s often than not somewhere in the middle.

If your car needs regular, low octane gas, but you “accidentally” filled up with premium, nothing much will happen.

If your car needs premium gas but you put in regular gas, then your ECU will adjust the engine’s performance to function with the lower octane regular gas. If you modded your car and meticulously balanced out the tune for power, then this is a frustrating outcome. In most cases however, this is okay, but as we’ve said before, it's always ideal to follow your car’s manual.

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Thankfully, we have pump attendants in the Philippines, so accidentally mixing fuels is usually avoided [Photo: Shell]

To sum it all up, the difference between regular gas and premium gas lies on their octane rating. Regular gas is also cheaper than premium gas. And no, your car will not gain additional mileage or horsepower just because you used premium fuel. Always follow the fuel type indicated in your car’s manual, and keep safe out there.

Regular vs Premium Fuel: FAQs

1. Which fuel should I choose? Regular or Premium?

Answer: For the right kind of fuel for your car, please consult your car’s manual.

2. Why is premium fuel more expensive?

Answer: Premium gas is more expensive because it requires more refining, mixing, and it also has more demand.

3. Is 100 RON gasoline available in the Philippines?

Answer: Yes, 100 RON gasoline is sold in the Philippines.

4. What is the lowest octane rating for gasoline in the Philippines?

Answer: As dictated by Philippine National Standards, the lowest possible rating for gasoline sold locally is 93.

5. What does RON mean?

Answer: RON means research octane number.

For more helpful car maintenance tips, and car buying and selling guides, keep it here on Philkotse.com.