Thi Hong Xuan, of the Engineering and Technology Department of the Ho Chi Minh City Agriculture and Forestry University, told Tuoi Tre that gasoline that was mixed with ethanol or methanol might to blame for the fires.

The use of gasoline with ethanol as a replacement for conventional gasoline produced from crude oil has become common in many countries, since the oil has become more scarce, and its prices on the world market have increased, especially in the US and Brazil, Xuan said.

Depending on the ethanol levels added to gasoline, manufacturers can have such gasoline categories as E5 (with 5 percent ethanol), E10 (10 percent ethanol), E85 (with 85 percent ethanol), etc. 

When added to gasoline, ethanol helps increase the octane value of the fuel, and a higher octane value means less gasoline is burned by the ignition of the spark plug, Xuan said.

Gasoline mixed with ethanol is more environmentally-friendly than conventional gas, since it helps reduce the presence of harmful substances in emissions from vehicle engines, such as nitrogen oxide, hydrocarbons, and, carbon monoxide.

However, depending on the volume of ethanol added to the gasoline, engines using such a mixture have their fuel operating system, sparking system, and compression rate, as well as a few other components, improved in order to enable them to use such a fuel, Xuan said. 

If such improvements are not implemented, the gasoline pipe may crack and the carburetor float needle may be damaged, leading to a fuel leak in the carburetor and a flooded engine, especially in engines using an electronic fuel injection (EFI) system.

In such a case, the leaked gasoline will catch fire if it is exposed to a spark coming from the vehicle’s electrical system. 

In Vietnam, in addition to the E5 gasoline that has been sold on a pilot basis on the market, many other kinds of fuel have been blended illegally by traders looking for profit.

Instead of adding pure ethanol (C2H5OH) to gasoline at an allowable proportion, they use methanol (CH3OH) containing foreign matter and water, resulting in a much lower octane value in the finished product than in the gasoline with ethanol.

“That means gasoline with methanol is more easily burned by the ignition of the spark plug than gasoline with ethanol,” Xuan explained.

Methanol is cheaper than ethanol, and will allow the traders of gasoline mixed with the chemical to achieve higher profits, Xuan said. 

Therefore, vehicle operators should only use gasoline from reputable petrol stations and regularly have their vehicles checked at warranty stations to detect any technical problems that may have arisen so that repairs can be made in time.

This Mazda burned down in Ham Rong Ward, Thanh Hoa City on December 27 night

29 motorbikes, 2 cars fire

From the beginning of the year, 29 motorbikes and 1 car have exploded into flames without any noticeable cause in different parts of the country, the Ministry of Public Security reported.

Most recently, a four-seat Mazda caught fire on Thanh Long Street, Ham Rong Ward, Thanh Hoa Province at 9 pm on December 27.

The same day, three motorbikes - a Wave, Daelim Citi, and a Daelim Motor, also burst into fire in Ho Chi Minh City.

One day before, similar incidents occurred to four other bikes in Hanoi, and a Lacetti car in Bac Giang Province. 

On December 25th, a Luvias and a Nouvo motorbike, both of which are manufactured by Yamaha, caught fire in Binh Dinh Province.

On Christmas eve, December 24th, a Union 150 cc bike exploded into flames in Tien Giang Province.