But it is not so simple with the content of the organic component. The designation E10 does not cover a single type of fuel. “Bio-alcohol can also be represented in E10 gasoline in the form of ETBE (ethyl-tert-butyl ether), which has completely different chemical properties,” points out Ladislav Červený, fuel quality expert at ORLEN Unipetrol.

Can you first explain what E10 fuel actually is and how it differs from E5?

At the outset, it should be mentioned that in 2018, European countries introduced uniform labeling of fuels for easier orientation of motorists in the range of fuels offered at home and abroad. Car gasoline containing up to 10 percent by volume of bio-alcohol is referred to as E10 fuel, while bio-alcohol is represented up to 5 percent by volume in E5 gasoline. However, the marking of petrol does not depend only on the proportion of bio-alcohol, but also on the oxygen content. Its concentration in the case of E10 can be up to 3.7% by weight and in the case of E5 up to 2.7% by weight. Whenever gasoline fulfills even just one of the listed conditions (either bio-alcohol content or oxygen content), for which it falls into the E10 category, the seller must mark it as such.

However, bio-alcohol can also be represented in gasoline in the form of ETBE (ethyl-tert-butyl ether), which has completely different chemical properties compared to bio-alcohol, even though it is produced from it.

With your Verva 100, which has been labeled E10 for a long time, how exactly is it?

As I have already stated, the labeling of petrol does not only depend on the proportion of bio-alcohol, but also on the oxygen content. Verva 100 premium gasoline does not contain any added bio-alcohol, but is based only on ETBE (ethyl-tert-butyl ether). ETBE is an oxygenated compound and its addition to Verva 100 increases the oxygen content above 2.7% by weight (while not exceeding 3.7% by weight) and therefore must be marked with the E10 symbol, even if it contains no added bio-alcohol. Therefore, we recommend Verva 100 to owners of cars that are not compatible with E10 gasoline containing bio-alcohol.

So, even though the Verva 100 is labeled as E10, can drivers who don’t want or can’t fill up with 95 octane E10 gasoline with bio-alcohol safely fill it up?

Exactly. The main difference between Vervy 100 and 95-octane gasoline is the octane number, but also the absence of standard added bio-alcohol, which is replaced by ETBE. Ethyl-tert-butyl ether, unlike bio-alcohol, does not bind water from air humidity, which extends the fuel’s shelf life. The advantage of Vervy 100 is also the low content of olefins, which tend to polymerize and form resin deposits. For the above reasons, we recommend the Verva 100, among other things, for longer-term storage, for example of a motorcycle during the winter.

Photo: ORLEN Unipetrol

Ladislav Červený, fuel quality expert at ORLEN Unipetrol.

And what about the veterans? Or maybe with garden equipment, which we also don’t often use during the winter?

Even in these cases, Verva 100 without added bio-alcohol is ideal, as it contains an above-standard dose of stabilizers to maximize shelf life. I already mentioned the low content of olefins, which tend to polymerize and form resin deposits. Our customers include motorists who also own pre-war vintage cars, and according to them, the Verva 100 has proven to be the best. I myself fill my motorcycle exclusively with Verva 100 and have never had a problem after the winter break.

For what reason is E10 petrol, i.e. the one that contains bio-alcohol, not suitable for some older vehicles?

Bio-alcohol is a solvent whose presence in gasoline leads to the “washing out” of plasticizers that are found in the hoses and seals of the fuel system of old vehicles. The absence of plasticizers causes hardening of plastic and rubber parts, which results in their cracking. The higher the concentration of bio-alcohol in the fuel, the faster the degradation process takes place.

However, I would like to mention that even if the owner of an old vehicle were to fill up with gasoline without bio-alcohol all the time, any plastic or rubber part could still crack due to its age. Therefore, even in the case of new vehicles, I recommend regular servicing to motorists.

Is there an easy way to tell if a particular car is not compatible with E10 fuel that contains bio-alcohol?

Gasoline with a bio-alcohol content of up to 10 percent by volume can be refueled in almost all vehicles with a gasoline engine manufactured after 2005, when the Euro 4 standard came into force. The compatibility of E10 gasoline with a specific vehicle can be easily verified on the website https://www.e10info. eu/cs/can-use-fuel-e10/. Newer vehicles always have the corresponding petrol symbol on the tank cap, which can be refuelled.

Traditionally, Škoda cars are the most popular vehicles in our country. How are the cars of the Mladá Boleslav car company doing?

According to Škoda Auto’s official statement, it is possible to refuel E10 fuel containing up to 10 percent by volume of bio-alcohol in all its models with a gasoline engine. The exception is the Felicia and Favorit models manufactured before 2002 with 1.3l-OHV engines with a power of 40 and 50 kW. The solution is to replace the rubber sealing rings in the fuel injection units. However, these are over 20-year-old models, so these parts are no longer available in the original. However, if needed, these seals should be available as aftermarket parts from aftermarket dealers. Owners of felicia and favorites can safely refuel Verva 100 without added bio-alcohol, even if it is marked with the E10 symbol.

Why are gas stations in the Czech Republic switching to E10 gasoline?

The switch to 95-octane gasoline in the E10 category is mainly due to the fulfillment of emission targets set by the European Union. The recently approved RED III directive increases the goal of saving greenhouse gases from the current 6% up to 14.5% in 2030. Reducing greenhouse gas emissions is ensured precisely by adding bio-components to fuels, as this is one of the cheapest options. The introduction of 95-octane gasoline in the E10 category also harmonizes the supply of said gasoline in the Central European region. Germany, Slovakia, Hungary and Austria have already introduced E10 gasoline, this year Poland also joined.

Many drivers are afraid of switching to E10. Do you think they have a reason?

Motorists are generally skeptical of bio-components in fuels. Personally, I am not surprised at all, because their disadvantages are mainly discussed among the motoring public. Yes, bio-alcohol has the ability to bind atmospheric moisture, which reduces the shelf life of gasoline. It can also react with fuel system hoses and seals in older vehicles, causing them to crack. On the other hand, compared to gasoline, bio-alcohol has roughly three times the heat of vaporization (the amount of heat needed to evaporate one kilogram of fuel), which results in less overheating of the engine. Its other advantages include cleaning effects (removal of deposits from the engine) and a high octane number (109 units).

Will refueling with 95 octane E10 gasoline have any effect on consumption?

A higher concentration of bio-alcohol in gasoline also increases the oxygen content. In order to maintain the stoichiometric ratio for ideal gasoline combustion, it is therefore necessary to slightly increase its dose into the combustion chamber. However, the increase in consumption is so negligible in this case that the motorist is unable to register it while driving. Motorists who claim otherwise are proof of suggestion.

Actual operating consumption is affected by the number of starts, starts and stops, acceleration rate, outside temperature, wind speed and direction, driving speed, air filter cleanliness, tire pressure, road surface and many other factors.