The Difference Between A92 and A95 Gasoline

Gasoline is a refined product of petroleum distillation, used as fuel for internal combustion engines or in everyday devices such as lighters and space heaters.

The commercial gasoline we use daily comes with specific quality metrics tailored to different engine types. One key criterion for distinguishing gasoline types is the **octane rating**, which measures the fuel's anti-knock capability.

The higher the octane rating, the greater the resistance to engine knocking. This explains the numbers in fuel designations: A92 (or RON 92) has an octane rating of 92, whereas A95 (or RON 95) has an octane rating of 95.

The selection between A92 and A95 gasoline is closely tied to the compression ratio of an internal combustion engine:

• Compression ratio under 9:1: Common in manual motorcycles (such as Honda Dream, Wave, Jupiter), which require A92 gasoline.
•  Compression ratio above 9.5:1: Typical in automatic scooters, which generally require A95 gasoline.

If a low-compression engine uses high-octane gasoline, the fuel may fail to burn completely, leading to fuel inefficiency, power loss, and deposit build-up that accelerates engine wear. Conversely, using A92 in a high-compression engine can cause **knocking**—pre-ignition before the spark plug fires—resulting in energy loss, engine overheating, reduced efficiency, and internal component damage.

Phasing Out A92 Gasoline and the Rise of E5 Biofuel

In contrast, **E5 biofuel** consists of 95% A92 mineral gasoline blended with 5% anhydrous ethanol (99.5% purity). Ethanol is derived from biological feedstocks, including plant fats, grains, and agricultural waste (such as straw and husk).

Studies show that burning E5 biofuel produces significantly lower toxic emissions than conventional fossil fuels. Due to its higher oxygen content, combustion inside the engine occurs more completely, boosting engine power while lowering fuel consumption.

• E5 Biofuel.

Regarding safety metrics, because ethanol possesses a higher octane rating than standard mineral gasoline, the final blended octane rating of E5 (blended on an A92 base) reaches approximately 93–94. This is particularly advantageous for vehicles in Vietnam, most of which feature compression ratios exceeding 9:1. Using standard A92 in these engines frequently causes knocking, engine wear, and power loss.

Some experts note that in older engines (manufactured before 1993), minor acid content in biofuel could potentially affect rubber gaskets, plastics, and polymers. However, for vehicles produced after 1993, this issue is virtually non-existent due to advancements in fuel delivery system materials. Consequently, the mild acidity in biofuel does not harm modern engine components, nor does it cause adverse side effects during combustion.

Does Vietnamese E5 Biofuel Quality Meet Global Standards?

Both E100 ethanol and RON 92 base gasoline undergo strict quality inspections by independent testing agencies (such as PV EIC and QUATEST) before warehouse entry to ensure compliance with current Vietnamese National Standards (TCVN).

Following inspection, E5 is blended at designated distribution terminals. Post-blending, regional Quality Assurance and Testing Centers (QUATEST 1 and 3) evaluate and certify compliance under **QCVN 01:2009/BKHCN** (National Technical Regulation on Gasoline, Diesel Fuels, and Biofuels). The finished E5 product must strictly meet **TCVN 8063:2009** (Unleaded gasoline blended with 5% ethanol – Technical requirements).

Thus, E5 biofuel undergoes rigorous quality control at every stage to ensure it meets international E5 specifications. After more than a year of widespread implementation across 8 provinces and major cities, no engine failures or technical malfunctions related to E5 usage have been reported.

Biofuels have long been adopted globally. The United States pioneered ethanol blending by introducing E10 (10% ethanol) in 2005, while Thailand introduced E10 and E20 (10% and 20% ethanol) in 2008.

Fuel Consumption Comparison: E5 vs. A92

Blending ethanol increases the octane value and allows fuel to burn more completely. Major global automakers explicitly confirm in their owner's manuals that engines are fully compatible with unleaded gasoline containing up to 10% ethanol by volume without voiding vehicle warranties.

Leading automakers—including General Motors, Ford, Daimler, Infiniti, BMW, Lexus, Nissan, Subaru, and Toyota—recommend using up to 10% ethanol-blended gasoline to enhance engine performance, reduce tailpipe emissions, and improve air quality. Many countries utilize E20 to maximize engine operational efficiency. Therefore, fuel economy with E5 is superior to that of standard A92.

Alternating Between E5 and Conventional Gasoline

Alternating between E5 and conventional gasoline poses no technical issues for internal combustion engines. Since E5 is formulated by adding anhydrous ethanol to a mineral gasoline base, switching between the two does not harm the engine. Both input components are certified by national testing centers prior to blending.

E5 biofuel with ethanol additive is poised to completely replace A92 gasoline.

Research demonstrates that E5 biofuel maintains its quality and stability for at least 6 months in storage. Vehicle owners who operate their vehicles infrequently can safely use E5 without worrying about fuel degradation or engine damage.

 Does E5 Biofuel Absorb Water During Storage?

While alcohol is naturally hygroscopic—which could theoretically pose a risk during humid weather conditions in Northern Vietnam—water absorption in practice is virtually non-existent. The ethanol used for blending is 99.95% pure (near absolute alcohol), containing almost zero water content. Consequently, E5 fuel does not trap moisture under normal storage conditions.

Why Is E5 Biofuel Cheaper Than A92?

Despite its superior technical and environmental advantages, E5 is priced lower than A92 due to government subsidies for consumers and key petroleum distributors. Specifically:

• Consumer Support:A direct subsidy of 500 VND/liter is applied by reducing price stabilization fund deductions compared to A92 and A95.
• Distributor Support: A subsidy of 250 VND/liter is provided to petroleum wholesalers to ensure profitability when blending mineral gasoline with E100.

Conclusion

As petroleum reserves decline and environmental pollution escalates, transitioning to biofuels is an essential step forward. Experts predict that biofuels will become the primary fuel source replacing fossil fuels in the near future.