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Octane VS Petrol – Which Is The Best Fuel For Motorcycle?

Saleh Md. Hassan
April 8, 2013

Octane Vs PetrolWhich Is The Best Fuel For Motorcycle? Hello riders, here I am motivated to focus on motorbike fuel. So, which we will use to run our bikes. I am pretty sure of your agreement with me about the importance of the issue. Thereof it is directly related to our pocket and mobility of the bike.

octane vs petrol

Commonly, most of the motorbikes in our country run by petrol or octane (Source). Only a few numbers of diesel-engine bikes were in the army which is out of order. Further, there are also some electric bikes which run over the country powered by electric motors. So, here my focus on petrol (gasoline) engine bike.

There are two categories of petrol engine bikes: 2 Stroke and 4 Stroke. Both are very popular in our country. Both of them uses near the same type of (internal) combustion to produce power from fuel.

Whatever here  I will go slightly for the core technical issues but discuss mainly on the fuel that we use. Then I will focus on how we can gain maximum utility considering our local scenario.

octane vs petrol which is the best in bangladesh

Octane vs Petrol – Our Fuel Type (In Bangladesh)

First, we need to know about our fuel octane vs petrol, what we are using, and what its standard is. In Bangladesh, there is a huge lack of information. Most of the situation general people live out of real information. Whatever commonly we use petrol and octane for our motorbikes.

Most of the people think petrol and octane are two different types of fuel. But by the name of petrol or octane actually, there are no differences. Both are internationally known and commonly named as “Gasoline” and chemical construction is also same (C8H18).

So we can call it either Gasoline or Petrol or Octane. Internationally there is some category of gasoline/petrol/octane. It differentiated by a quality number that called an OCTANE NUMBER or RON (Research Octane Number).

Thereby, internationally the standard rating of gasoline starts from Octane86 (RON86) and goes over 91 and even 102. These different rated gasoline are the same gasoline with the same chemical construction. But the difference is about their enhancing additive and detergents.

Hence, some of those boost fuel capability thereby the capability of expansion, compression, and controlled combustion. Thus it works for smooth combustion mechanism in the cylinder.

Thereby no hiccup or knocking sound comes from piston, valve or connecting rod. So no regression or back force tendency takes place. Whatsoever, here I will use the word Gasoline generally to mean the fuel, Petrol or Octane.

Octane vs Petrol – Fuel Action Line

To understand the need for quality fuel we need to know the basic line of fuel action. After mixing the air and gasoline the mixed vapor injects to the cylinder/combustion chamber.

Then the piston compresses the mixed vapor and the spark plug fires the mixture. After that, the mixer makes a huge boom of gas. Thereby, the gas expanded with forces and pushes the piston out of the cylinder.

Here the fuel needs some extra capability to be expanded and compressed hugely. Buth the volume should be in a controlled ratio. It’s due to make the whole combustion mechanism smooth and controlled.

Otherwise, the combustion will not be controlled and the power production ratio will not be equal every cycle. Thus in the uncontrolled combustion, the piston, connecting rod and valve activity will hamper.

Resulting it will make metallic noises like piston hiccup, knocking from the valve and connecting rod, etc. (Internationally this noise is called Engine Knocking). Further, the engine can make regression, back force or can vibrate a lot.

Leaded Gasoline VS Unleaded Gasoline

In the earlier stage, the old model gasoline engine was not a high performer engine. So they could be run with a simple type of gasoline. But day by day the gasoline engine action and performance improved.

It needed smooth and controlled combustion for vibration-free and high-speed performance. So the extra but controlled performance needed from the gasoline.

So the researchers researched out the Lead (Pb) can be used as a booster to increase the fuel-combustion capability. It was one of the cheap & best boosters for gasoline. So the Lead (Pb) has been used with gasoline worldwide till the end of 20th century. And it is known as Leaded Gasoline.

But it started to be banned to mix the Lead with gasoline at the end of the 20th century. It’s due to the direct and indirect harmful effect on nature and human.

Due to the harmful effect of Lead (Pb), there was an activity to ignore the use of leaded-gasoline. Thus it encouraged to use other additives to keep the gasoline capability in the level (RON) which gained by the lead.

So researchers started to use other alternative additives instead of lead and it called as Unleaded Gasoline. Therefore, now only the unleaded gasoline is recommended to use in internal combustion engines.

Octane vs Petrol – Leaded or Unleaded and Why

This question is not related to the common gasoline user of our country. Further, it can be elaborate in different writing like with the head Fuel Booster. But for the interested person, I should touch this point at least a little.

Lead is a very economical and effective boosting additive. It can boost gasoline capability hugely. And it’s much easy to gain the higher RON by adding Lead with Gasoline.

So in earlier years, it frequently used to boost fuel capability. And still in the racing vehicles, in aviation fuel, and in some limited countries it is used with fuel. [And there are other things like the Nitrous Oxide (NOS) to increase the engine power for limited time].

But the Lead has a huge and long term bad impact on the human body and nature. So we should avoid leaded additive and gasoline for the longterm use.

And there is nothing to be disappointed with unleaded gasoline. The modern lead-free gasoline has the capability to run your bike or car engine with optimum performance.

RON (Research Octane Number)

RON is an important term of gasoline that certifies the grade. When the gasoline engine getting modernized, it needed more capability from gasoline for increased and controlled performance.

Then some additive and boosters used to raise the gasoline capability level to gain controlled high performance. And Lead was the best-boosting additive, which can raise the gasoline capability at a standard level.

Also Read: 7 Tips To Boost Your Riding Skill

But the poisonous effect of lead revealed. Then the researchers researched out other alternative boosters like ethanol, methanol, toluene, and other additives.

Those were somewhat costly and less powerful than lead. But upon development now those can boost the capability of gasoline in a controlled way. Further, they have a minimum harmful effect on nature.

Hence, finally, internationally it authorized to add ethanol and other additives to keep the gasoline capability level in a standard. They set some capability standard of the gasoline considering the additive limit and fuel capability. And this is the Octane Number or RON (Research Octane Number).

Octane vs Petrol – Scenario of Gasoline In Bangladesh

By international law, it is mandatory to stick the RON label on the dispenser machine of gasoline. So, people should know for which quality of gasoline they are paying for.

And if there more than one type of gasoline in the fuel pump, those should clearly be noticed by yellow RON-sticker. Like RON 87, RON 91 or Octane 87, Octane 91.

Unfortunately in our country Bangladesh we never have seen such informative fuel pump anywhere. But though we do not know the RON of our gasoline, we use two grades (RON) of gasoline.

They are known as “Octane & Petrol” (like “Mom & Mother”. . . . funny!).  Now the question is, what the RON of our gasoline for Octane & petrol.

In this writing, earlier I mentioned the minimum RON of international standard is RON86 and goes above RON91. So we can expect as our Petrol is RON86 at least. Further, our Octane RON can be more. But in my finding, I could be sure that our Petrol is only RON80 and Octane is RON95.

Moreover, I found some discussion about the proposal to the ministry to increase the petrol RON from 80 to 86. Whatsoever, most of the users don’t know about the RON. So a common question comes “Which should we use from Petrol vs Octane and why?” And I will add, “For which bike?

octane vs petrol fuel pump

Octane vs Petrol – What Should We Use?

If you in dilemma about octane vs petrol then it’s for you. If our petrol would have RON86 at least then we should not need to go for higher-grade fuel. Thereof, until today our petrol is RON80. So it bellows of international standard. So normally we cannot use it in our bikes. But in the real, we’re doing it frequently.

Now the question, do most of the user in our country uses the high-performance bikes?  The answer is No. Most of us use only bellow 150cc bikes. Those are designed with single-cylinder, single-piston, with only two valves, with the compression ratio bellow 9:1. And some of their engines build-quality is also very economical. Hence, nothing can improve their performance.

And there is a large number of two-stroke bikes running in our country. So our petrol with RON80 is quite ok for those regular four-stroke bikes. And two-stroke bikes are not that much sensitive (Several times accidentally I have ridden my Honda H100S CDI with kerosene).

But here we should be confirmed about purity. Whether it is really RON80 or it’s contaminated with kerosene or other contaminants.

In our country, fuel contamination is very much common in rural areas even in Dhaka city. So we don’t get pure fuel anywhere. Therefore, contaminated petrol with RON80 easily can damage the engine. And it’s not healthy to use that grade in our motorcycles.

Available Octane Grade In Bangladesh

Now I am going for the Octane. Our octane grade is RON95 or Octane95. Now the question is where we can use this octane? Yes, we can use it in our motorcycles even which comes with the compression ratio bellow 9:1.

Further, the happy thing is high performances bikes are gradually entering in our Bangladeshi market. Hence, obviously, those should run with Octane with RON95.

Further, most of the 150cc and higher displacement bike in our country have the performer four-stroke engines. Those engines are designed with higher compression ratio, and also some time with more than two valves.

And they required for standard or higher-grade gasoline (internationally at least RON87-RON91) where our petrol is only RON 80. So mandatorily we should use our octane for those bikes.

Again, there are some climate issues in our country. In the winter season most of the area of our country the weather remains very much cold. So our petrol cannot give effective performance in the winter.

Moreover, the ignition problem is a big hassle in the cold weather. So higher rating octane obviously needed in cold weather. Here our Octane takes the place

Mixing Petrol with Octane

There is a common malpractice in our bikers to mix petrol with octane in various ratios like 1:1, 1:2. Most of them have no clear idea of what they are doing and why.

They only do that with some miss concepts. Further, they don’t know whether their bike needs petrol (RON80) or octane (RON95) or something else.

Whatsoever, Generally, two different RON gasoline can be mixed to get the average RON like (RON80+RON95)/2=RON87.5. Yes, this can be done when the two different RON gasoline is composed of the same type of booster, detergent and antioxidant additive only.

But in Bangladesh, we are not sure about our Petrol & Octane additive composition. We don’t know whether they have composed of the same type of chemical additives or not.

Again we can’t be sure about the purity or contamination of petrol or octane. So it’s not only better but the best practice not to mix petrol with octane in any ratio.

Also Read: Top 5 Tyre Brand In Bangladesh

So, only in some uneven situation, we can go for only a 1:1 ratio (50%:50%) for the average or old model bike. In such a case, use petrol first and observe the bike performance.

If needed then go for octane. And again observe for the performance change. If something bothering you then go for 50%:50%. Again observe and take a final decision considering your bike performance.

This concept is not for high performer bikes. Use only octane (RON95) without mixing any type of external boosting additive.

Does Our Octane Over Heat Motorbike Engine?

Yes, the motorcycle engine overheating is an issue in consideration of the quality and specification of the engine. You need to know, does your motorcycle engine need higher RON or not.

If your bike is with bellowing 150cc engine with compression ratio bellow 9:1 then you can use only petrol confirming its purity. Otherwise go for 50%:50% (Octane : Petrol) and it is also considered in the winter season.

Using higher RON gasoline would really overheat the low-capacity and pure specification engine especially at summer season.

But when your bike carrying a high-performance engine with a wider compression ratio, then use only octane (RON95). It will never overheat your bike engine. Hence, the heating is standard and it is normal.

Should A New Motorcycle Use the Lower RON?

This is also a misconception. People think the new motorcycle should use petrol (lower RON) and older should use octane (higher RON). But it is good to use better RON gasoline for the new bike engine. It helps in the efficient Break-In (run-in), running in the first 2,000km.

Commonly, in the break-in period, the motorcycle speed remains low, RPM remains low, and the trip is also shorter. So, no scope for prolonged running and overheating the engine. Moreover, a perfectly heated engine and internal parts get perfectly polished. So don’t hesitate using octane in your new motorbike at least for the first 2,000 km.

Do we need to go for higher RON when using a lower RON Gasoline?

If you search on the web, you will find no one encourages going for higher RON than recommended from the bike manufacturer. When you feel the need to go for higher RON, then you can use it to gain specific utility.

Using higher RON in a low-performance engine may cause various issues. On the counter using low-grade RON Gasoline is also will hamper the real performance. Hence, its better and recommended to stick with the manufacturer instructions and continue with recommended RON of fuel. That’s it.

Fuel Booster & Detergent Additive – Should I Use?

The manufacturer does not recommend any type of external fuel additive and booster for their bike engine. But some of the hardcore users tend to use some fuel booster, detergent additive for there bike. Most of the case; they are harmful to the carburetor/injector, engine, and catalytic converter.

When those are used for a longer period those corrode the sharp edge of the piston, valve, cylinder body, and damages spark plug, catalytic converter, etc. So those only can be used in sports bike to gain short time utilities. So, it’s better to avoid them and take care of the bike with regular routine maintenance.

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Using Higher RON Gasoline in Low-Performance Engine – Any Problem?

This is just wastage of money as well as fuel. You will see the engine getting started fast even in cold weather with a deep sound and throttle responding immediately. But not to be happy as it will reduce the bike mileage.

The engine will get overheated. Top speed could be gained easily but reduce engine life creating overpressure in the combustion chamber.

Sometime pre-ignition may occur, or some time engine misfire with huge sound over silencer. Thus the piston, piston ring, connecting and the cylinder will ruin soon.

Using Lower RON Gasoline in High-Performance Engine

The engine will not ignite properly even pulling the choke lever or even in hot weather. Combustion will not be perfect and smoke will be seen at the end of the exhaust.

The engine will sound harsh. Sometime may make metallic noises like piston hiccup, knocking sound from the valve, and connecting rod, etc.

Here, little high fuel-economy may be gained but the engine gets overheated. Throttle will not respond fast and will lose its smoothness. Further, the engine may tend for back force and may vibrate.

Top speed or acceleration could not be gained properly. The spark plug will be oily & carbonized soon and the engine will misfire.

Octane vs Petrol – Using Contaminated Gasoline:          

In our country, fuel contamination is a very common issue. Most of the time we had to use contaminated fuel. Contamination does a little problem for the diesel driven engine.

But in terms of gasoline engine like motorbikes contaminated gasoline has a very bad impact. Sometimes we have no choice rather using those contaminated gasoline (petrol or octane). In such a situation, obviously, the RON rating remains out of range.

Whatever if we use those type of fuel then:

1                 The engine will not ignite swift. Several attempts will be needed to start the engine even choking at hot weather.
2                 The engine could misfire due to improper combustion. Smoke will be seen at the end of the exhaust.
3                 Throttle response will be delayed and will make a back force when accelerating the throttle quick.
4                 The engine will make harsh noises, sometimes like piston hiccup, knocking from piston ring, valve, connecting rod, etc.
5                 The engine will vibrate.
6                 Sometimes the engine could stop suddenly ridding in higher speed.
7                 Top speed will not be gained.
8                 The engine will lose all of its smoothness.

octane vs petrol best fuel for motorcycle

You can be sure more about contamination when:

1                 Spark plug gets carbonized frequently.
2                 Spark plug gets burned with dark black color (In perfect combustion with solid fuel it burned to ash or brown color)
3                 The spark plug will be oily. (in perfect combustion with solid fuel it will not be oily)
4                 Spark plug damages soon.
5                 Cylinder head, piston head, valves will be carbonized soon. And there will be oily sediment with the carbon.
6                 The exhaust will sound bad and produce more smoke even in the four-stroke engine.
7                 In case of four-stroke bike exhaust pipe can throughout a little oily smoke (two-stroke engine does it frequently)

best fuel for motorcycle

Testing a Gasoline for Quality:

There is no way to test the purity of gasoline without the laboratory test. But from the above-mentioned symptom, we can assure about the impurity.

Further, we can do a little by our own to test the workability of certain gasoline. So, to check the gasoline just collect a few (petrol or octane) from the source. Take a little amount of gasoline in your hand and rub it with two hands.

Also Read: NGK Iridium Spark Plugs & How Its Works?

When the fuel vaporized take a keen look into your hands. If your hand seems dry then the gasoline is ok. But if there oily sediment or residue found, then it has been mixed with some other contaminant like kerosene or diesel.

If you have a keen smell, then take a smell of your hand. Maybe you can be sure if it mixed with kerosene or diesel or turpentine oil.

Another way, take a steel plate. Drop some gasoline on the plate and fire it throwing a match stick. When the gasoline burnt off and the plate temperature becomes normal, then observe for the oily sediment and take smell for the contaminant.

Octane VS Petrol – The Writer’s Clause

So riders, hope this writing may help you to know more about Octane Vs Petrol and the best fuel for motorcycle. Thanks for your patient concentration on this writing. I will be happy for your further quarry, suggestion or addition, and also for your valuable comments.

Information courtesy: Wikipedia (the free encyclopedia), The Federal Trade Commission, Petro-Canada, www.howstuffworks.com, www.turborick.com, www.about.com, The Economist, Eastern Refinery Ltd, Atlas Bangladesh Ltd.

Image courtesy: Wikipedia (the free encyclopedia), green-planet-solar-energy.com, Bangladesh Petroleum Corporation.

By: Saleh MD Hasan

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