Which type of gasoline should I use for my motorcycle: regular or premium? We'll explain the correct choice, the reasons why, and answer common questions.

There are two types of gasoline for motorcycles: "Regular" and "High-Octane"

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Motorcycle gasoline is usually either "regular" or "high-octane," and most motorcycles use regular, with the exception of some high-performance or imported models.

The type of gasoline to use is specified in the motorcycle's owner's manual as the designated fuel. Be sure to check the designated fuel and use either regular or high-octane.

Differences between Regular and High-Octane

The difference between regular and high-octane gasoline lies in their "octane rating." According to Japanese Industrial Standards (JIS), gasoline with an octane rating of 89 or higher is defined as regular, and gasoline with an octane rating of 96 or higher is defined as high-octane.

The octane rating indicates a fuel's resistance to knocking (abnormal combustion). A higher octane rating means less knocking, so high-octane gasoline is less prone to knocking than regular gasoline.

Furthermore, most high-octane fuels contain "cleaning agents" that clean the engine's interior, and high-octane gasoline is about 10 to 15 yen more expensive per liter than regular gasoline.

Does high-octane fuel improve motorcycle performance or increase power?

Even if you put high-octane gasoline into a motorcycle that specifies regular, you cannot expect improved performance or increased power.

Engines are designed to match specific types of gasoline. Generally, high-octane is specified for imported motorcycles and high-performance large motorcycles.

While many high-octane fuels contain cleaning agents, they are more expensive than regular fuel, increasing running costs. Therefore, it is safer to use regular fuel for motorcycles that specify regular.

Does the type of gasoline affect fuel efficiency?

In most cases, there is no change in fuel efficiency between regular and high-octane gasoline.

Although fuel efficiency may slightly improve, the price difference between regular and high-octane is about 10 to 15 yen per liter, so the improvement in fuel efficiency is not enough to offset the price difference.

Many high-octane fuels contain cleaning agents, which keep the engine clean. However, considering the price difference, it is safer to use regular fuel for motorcycles that specify regular.

Fuels not to be used in motorcycles

While there are various types of fuel, "diesel" and "kerosene" cannot be used in motorcycles. Using the wrong fuel can lead to engine damage.

Although there's no problem putting high-octane fuel in a motorcycle that specifies regular, diesel fuel is for diesel engines and has a higher boiling point than gasoline. If put into a gasoline engine motorcycle, it won't start.

While it's rare for motorcycles, there are annual incidents where people mistakenly put diesel into light cars, leading to engine breakdowns.

Also, kerosene is fuel used for heating appliances like oil heaters and fan heaters. Putting it into a motorcycle will cause engine trouble, preventing it from starting. Therefore, when refueling, always use the gasoline specified in the owner's manual (regular or high-octane).

What to do if you put in the wrong fuel

If you put in the wrong fuel, the engine may not start, or even if it does start and you drive, it will stop soon.

If you realize you've used the wrong fuel, immediately stop the engine in a safe place or somewhere that doesn't obstruct traffic, and call a motorcycle shop for pickup.

Moving the bike can cause the fuel to circulate through the engine, potentially causing more damage. Therefore, it is safer to stop the engine and call for assistance.

Use the correct gasoline for your motorcycle's engine.

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It is necessary to use the appropriate fuel for your motorcycle. You can check the type of fuel to use in the motorcycle's owner's manual or on the motorcycle manufacturer's official website.

For models that are no longer in production, the information may have been removed from the official website. In such cases, it is advisable to check the motorcycle's owner's manual.

Check the type in the owner's manual

The type of fuel for a motorcycle is listed in the owner's manual. You can also find owner's manual information from motorcycle manufacturers' download sites.

Some manufacturers offer PDF downloads, and you can view owner's manuals for specific motorcycles through a search, so you can confirm the fuel type even if you've lost your manual.

Additionally, if you want a physical owner's manual issued by the manufacturer, you can order it at a manufacturer's shop, so you may want to use this option if needed.

Check the type on the manufacturer's official website

For motorcycles currently in production, the type of gasoline to be used is listed in the specifications section on the motorcycle manufacturer's official website.

Although you can usually check on the official website for a few years after production ends, information on models discontinued long ago may no longer be available.

If you cannot find the information on the official website, check the owner's manual or refer to the manufacturer's owner's manual page as mentioned earlier.

Is it okay not to ask the gas station staff?

Since fuel is supplied at gas stations, some might think it's okay to ask the "gas station staff," who are professionals in handling gasoline, what type of fuel to use.

Most motorcycles are designated to use regular fuel, but imported or high-performance motorcycles may require high-octane. Very few gas station staff members have detailed knowledge of which motorcycles require high-octane fuel.

For the reasons above, it is more reliable to check the motorcycle's owner's manual or the manufacturer's official website to confirm the correct fuel type.

Motorcycle Gasoline FAQs

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This section summarizes frequently asked questions and answers regarding motorcycle gasoline.

It will help resolve your questions about motorcycle gasoline, so please check it out.

Is it okay to use the wrong type of gasoline?

There is no problem using high-octane gasoline in a motorcycle that specifies regular. However, if you mistakenly put in a non-gasoline fuel like diesel or kerosene, the engine will stop or fail to start.

If you use the wrong type of fuel, you must immediately stop the engine to prevent the fuel from circulating through it.

You won't be able to ride until the fuel is replaced. If the engine hasn't started yet, have the gas station drain the incorrect fuel, or ask a motorcycle shop to inspect and repair it and replace the fuel.

What happens if I mix regular and high-octane gasoline?

For motorcycles with electronic control of ignition timing, mixing high-octane and regular gasoline is fine. However, for older motorcycles with carburetors, it's safer not to mix them.

If you mix high-octane with a regular-spec motorcycle, the engine will be slightly cleaned by the cleaning additives in high-octane, but there will be no improvement in engine performance or fuel efficiency.

Conversely, if you mix regular gasoline with a high-octane specified motorcycle, it will almost certainly not cause a breakdown like engine stalling. However, there's a possibility that the engine won't be able to perform to the level the manufacturer intended when designing it.

Also, if you use the wrong gasoline specified by the manufacturer and it leads to a breakdown, you might not be covered by the manufacturer's warranty. Therefore, it's safer to use the specified gasoline without mixing.

Is it okay to put regular gasoline in a high-octane designated motorcycle?

While putting regular gasoline in a motorcycle designed for high-octane won't cause a breakdown such as engine stoppage, it is safer to use the gasoline specified by the manufacturer.

High-octane designated motorcycles are often imported bikes or high-performance super sports bikes, and since they are designed to perform with high-octane fuel, using regular gasoline will prevent them from achieving their full potential.

Due to economic reasons, you might be tempted to use cheaper regular gasoline instead of high-octane. However, high-performance motorcycles often have high compression ratios and therefore typically require high-octane fuel, which is less prone to combustion issues than regular gasoline.

Also, high-octane often contains cleaning agents. Therefore, for motorcycles designated for high-octane, it's best to continue using high-octane to ensure the engine performs at its best and stays clean inside.

Are there any benefits to putting high-octane in a regular-designated motorcycle?

There is almost no benefit to putting high-octane gasoline in a regular-designated motorcycle. Using high-octane in such a motorcycle will not increase engine output or improve fuel efficiency.

However, high-octane often contains cleaning agents, giving it a higher engine cleaning power than regular. So, in terms of cleaning the engine's interior, there is a benefit.

However, engines have a self-cleaning effect from combustion, etc., and while regular gasoline also has an engine cleaning effect (though not as strong as high-octane), it can be said that the benefits do not outweigh the price difference between regular and high-octane.

The self-cleaning action of an engine increases with higher RPMs. Therefore, motorcycles that operate at high RPMs, such as mopeds, will have a greater engine self-cleaning effect than standard motorcycles.

Is it okay to mix high-octane and regular gasoline?

For motorcycles that use electronic control to manage engine ignition timing, mixing high-octane and regular gasoline is generally fine. However, for older carbureted motorcycles, it's safer not to mix them.

If you mix high-octane with a regular-specified motorcycle, the engine cleaning effect from the high-octane additives will offer some cleaning, but it won't lead to improved engine performance or fuel efficiency.

Conversely, if you mix regular gasoline into a high-octane-specified motorcycle, it will almost certainly not cause a breakdown such as engine stopping. However, there is a possibility that the engine's performance will not be fully realized as intended by the manufacturer during design.

Furthermore, if you use the wrong type of gasoline specified by the manufacturer and it leads to a breakdown, your manufacturer's warranty might be void. Therefore, it is safer to use the specified gasoline without mixing.

What if I don't know the type of gasoline for my motorcycle?

If you don't know the type of gasoline for your motorcycle, check the owner's manual as it is listed there.

If you have lost the owner's manual, you can view or download it from the motorcycle manufacturer's website. You might also be able to order an owner's manual from a motorcycle shop (for a fee).

For motorcycles currently being sold, you can check the type of gasoline to be used by looking at the specifications of the relevant model on the motorcycle manufacturer's official website.

Summary

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Each motorcycle has a specified type of gasoline, and it is best to use the designated gasoline.

In addition to gasoline, there are other fuels available at gas stations, such as diesel and kerosene. However, putting these fuels into a motorcycle will cause it to stop working or lead to breakdowns.

You can check the type of fuel for your motorcycle in the owner's manual or on the manufacturer's official website. If you are unsure what kind of gasoline to use, please check the owner's manual.