Đỗ Văn Tuấn, chairman of the Biofuels Association. — Photo moit.gov.vn

As Việt Nam officially rolls out E10 biofuel nationwide from June 1, concerns and conflicting claims about the fuel’s impact on vehicles have spread widely across social media.

Đỗ Văn Tuấn, chairman of the Biofuels Association and a long-time ethanol researcher, told media about the realities of E10 usage, common misconceptions and what consumers should know as the country moves further towards cleaner fuel adoption.

When was E10 fuel officially introduced to the market? How much has been consumed so far, and what have drivers using E10 before June 1 experienced?

E10 biofuel has been available on the market since early May. Petrolimex began distribution at the beginning of May, while PVOIL started supplying E10 on May 15.

To date, tens of millions of cars and motorbikes have already used E10 petrol. Every day, millions of vehicles continue operating normally on roads across the country. This is clear evidence that E10 is compatible with vehicles currently in use in Việt Nam.

Consumption volumes have also been significant. Petrolimex alone accounts for roughly 75 per cent of the domestic fuel market, equivalent to around 750,000 cubic metres per month. With such usage volume, the reality is that most vehicles running on E10 are operating normally and reliably.

These early results show that E10 has been well accepted by the market and is suitable for the vast majority of vehicles in Việt Nam.

Many people remain concerned about the compatibility of E10 with vehicles. What is your response to claims that E10 may damage engines, cause overheating or increase the risk of fires and explosions?

The characteristics of E10 mainly affect certain non-metallic materials, while metallic engine components are not impacted. Some vehicle parts, such as fuel hoses, seals and components within the fuel system, are made from non-metallic materials.

For motorcycles and cars manufactured in recent years, especially since around 2009, manufacturers have already used materials designed to be compatible with E10. As for older vehicles, if non-metallic components such as fuel hoses or seals deteriorate, they can be replaced relatively easily at repair shops.

E10 is therefore not the cause of engine damage in cars or motorcycles.

The biofuel also does not cause engines to run hotter. In fact, E10 contains a higher oxygen content than conventional gasoline.

Higher oxygen levels improve combustion efficiency and generally result in lower combustion temperatures. Theoretically, E10 may even help engines run cooler rather than hotter. Claims circulating online that E10 causes engine overheating are not supported by scientific evidence.

As for concerns about fire or explosion risks, there has been no assessment from experts or countries already using E10 suggesting that this fuel increases such risks.

Some fire incidents were reported before 2015 during the rollout of E5 gasoline in Việt Nam. However, at that time, the issue was linked to counterfeit fuel made by illegally mixing methanol into gasoline instead of ethanol. Methanol can seriously damage fuel systems, especially fuel lines, and may have contributed to certain fire incidents.

By contrast, E10 itself has not been identified as a cause of increased fire or explosion risks in vehicles.

Some consumers believe vehicles consumes E10 more than RON95. What is your view on this?

Regarding claims that E10 leads to higher fuel consumption, it is true that the energy content of E10 is about 3 per cent lower than that of RON95. Theoretically, this could result in fuel consumption increasing by around 3 per cent.

However, E10 also has an octane rating roughly 2–3 per cent higher than RON95. A higher octane rating can improve engine stability and efficiency. In other words, there are two opposing factors at play: one may slightly increase fuel consumption, while the other may improve engine performance.

As a result, it is difficult to conclude which factor has the greater impact in real-world use. In addition, E10 was introduced during a period of extreme heat across many regions of Việt Nam, particularly in the northern and central regions. Hot weather itself can increase fuel consumption, which may have led some people to associate the issue with E10.

Based on current scientific understanding, there is no clear evidence that E10 leads to more fuel consumption than RON95.

Some users have reported issues such as jerking, power loss or stalling after switching to E10. How do you assess these cases, and what should consumers do if they experience similar problems?

A small number of older vehicles – especially older motorcycles – may experience jerking, hesitation or even stalling when first using E10. However, this does not mean E10 damages the engine.

Ethanol is a strong solvent. When E10 is introduced into an older fuel system, it can loosen dirt and deposits that have built up over many years inside fuel tanks and fuel lines. These deposits may then clog injectors or other parts of the fuel system, affecting fuel delivery to the combustion chamber. This can lead to issues like jerking, hesitation or stalling.

Fortunately, the solution is relatively simple. Vehicle owners only need to have the fuel tank, fuel lines, carburetor or injectors cleaned at a repair shop. In some cases, worn fuel system components may need replacement. After cleaning and maintenance, vehicles generally return to normal operation and usually do not experience the same issues with subsequent E10 use.

Many people, especially owners of older vehicles, want to know whether E5 gasoline will remain available on the market. Could you clarify the roadmap for E5?

Under Circular 50, E5 gasoline will continue to be allowed on the market until December 31, 2030. The Government’s decision to maintain E5 during the transition period reflects the fact that E5 has been used in Việt Nam since 2018 and has already been on the market for around eight years.

During that time, E5 has proven compatible with the majority of vehicles currently in use in Việt Nam. Continuing to supply E5 not only helps maintain market stability, but also provides consumers with more choices, especially those using older vehicles or those who prefer to continue using E5 during the transition period.

For agricultural machinery and equipment, should users choose E5 or E10? If E5 is phased out in the future, will agricultural equipment face difficulties switching to E10?

In practice, testing has shown that agricultural machinery can also operate on E10. However, for some very old agricultural equipment, the Ministry of Industry and Trade and the Ministry of Science and Technology recommend continuing to use E5.

That is why maintaining E5 through 2030 provides a relatively long transition period for users of older agricultural machinery to continue using them with a suitable fuel option.

After that point, not all agricultural equipment will suddenly become incompatible with E10. Most equipment should still be able to use E10 normally. However, some very old machines may eventually need replacement as part of the natural process of technological modernisation.

As a long-time ethanol researcher, what advice would you give consumers now that the E10 rollout officially began on June 1?

Perhaps the most convincing answer lies in global experience. Today, E10 is widely used in countries across Europe as well as the US, China, India, Thailand and the Philippines. This is not a new or experimental fuel – it has already been used successfully in many countries for years.

Consumers can thus feel confident using E10. If this were the first time E10 had ever been introduced anywhere in the world, public concerns would certainly be understandable. But in reality, E10 has already been thoroughly tested through long-term use internationally.

My advice is simple: consumers should judge E10 based on their own real-world experience. They should not allow unverified information circulating on social media to shape their views without practical evidence or first-hand experience. — VNS