Is ethanol harmless to your engine?

Fuel: E10 is harmful to the engine oil and has no advantages

The ecological benefits of adding bio-ethanol to gasoline are becoming more questionable every day. Now that consumers' uncertainty about the new E10 fuel has led them to flee to the expensive SuperPlus gasoline and the industry has stopped E10 production, further discoveries could finally ruin the reputation of the biofuel. Because the maintenance of the cars will probably also be more expensive, as E10 is suspected of using the engine oil more than normal fuel. The consequences: lower lubricity and higher engine wear.

Water gets into the engine oil

"The ten percent ethanol content in gasoline also increases the amount of water in the engine. The water condenses from the combustion gases and gets into the oil, which is diluted and ages faster," explains Thomas Brüner, Head of Mechanics Development at BMW. The oil dilution is a serious problem for the engine experts - so serious that the competitors BMW and Daimler formed a joint research team at short notice, which is now to carry out special practical tests. The problem is apparently still unknown to the mineral oil companies. "We do not deal with technical issues," says a spokeswoman for the mineral oil industry association.

Experts discovered a similar oil problem months ago with diesel, to which up to seven percent fatty acids from rapeseed oil and methanol are added. Here the engine oil forms acids through a chemical reaction with the biocomponents of the fuel, which eventually thicken and literally clog the engine. This is one of the reasons why the mineral oil industry was unable to increase the proportion of bio-substances in diesel in order to achieve the required overall quota in fuel. Therefore, the ethanol in gasoline had to be increased from five to ten percent (E10) in order to avoid the threat of fines to the state.

Drivers cannot check the oil quality in practice. Experts advise pulling the dipstick regularly. If it shows a higher oil level than the last time it was checked, there is a suspicion that the oil has been diluted. However: some modern engines no longer have an oil dipstick. Here sensors measure the oil level, but this is not so accurate.

The oil change interval is shorter

The car manufacturers do not want to further unsettle their customers. "The use of E10 in our gasoline engines is basically harmless," says BMW engineer Brüner, but at the same time emphasizes: "Depending on the country and the fuel quality available there, we may have to shorten the oil change intervals."

How good German E10 gasoline is and whether there is a risky oil dilution in the engines, the tests should show in the next few weeks. In this case, too, the car owners will probably foot the bill: with a six-cylinder like the BMW 325i, each additional oil change costs a good 200 euros.

Meanwhile, environmental groups and scientists are distancing themselves from E10 and questioning the fuel. This also includes the office for technology assessment at the German Bundestag, which advises the members of parliament. In a 300-page report based on various reports, the Berlin experts question the ecological benefits of biofuel for car engines. Instead, the experts believe that the energy generated from biomass could be used more effectively to generate electricity and heat.

"The combined heat and power generation currently and for the foreseeable future has the better potential for saving greenhouse gas emissions," says the study. As a consequence, the biofuel quota for gasoline and diesel would have to be gradually reduced and finally abolished completely. Especially since the consequences of a misfuelling of around three million vehicles in Germany that cannot tolerate E10 will cause irreversible damage.

Even four-year-old cars can be damaged

The fact that it can even hit four or five year old cars like VW Polo, Lexus IS or Toyota Avensis is due to the structure of some engines and the materials that were used for them. Because alcohol, the proportion of which has now doubled in E10 petrol, removes water from neighboring substances. According to TÜV Süd, this leads to their "embrittlement" in seals, which means that they can no longer fulfill their task. In addition, according to a statement from TÜV Süd, "when it comes into contact with other materials, corrosion-accelerating substances (for example chlorides) are formed, and complexes are formed on some metals that intensify the corrosive effect."