‘Problems with E10 may only arise after a long standstill’

E10 petrol can cause problems with long stationary cars rather than E5. This is because E10 attracts more moisture, with potentially harmful consequences. For that, a car really has to stand still for a considerable time, emphasizes RAI Association. There is also a possible problem due to the longer use of winter fuel.

Now that there is much less driving due to the corona crisis, many cars remain stationary for a longer period of time. In the meantime there is of course fuel in the tank and in case there is E10 in the tank, extra caution is advised. E10 contains up to 10 percent bioethanol, which has the property of absorbing moisture from the environment. This can cause moisture to enter the tank and lead to problems, Techzle reported on Wednesday.


With a long standstill, this moisture will collect together with some alcohol at the bottom of the tank. In addition to possible oxidation, because this water-alcohol substance in the tank is corrosive, another problem may also arise. When the car is driven again and a lot of moisture has settled in the tank, that moisture (via an atomized water / alcohol mixture), together with the water vapor released during the combustion of petrol, can end up in the cylinder via the injectors. When the engine is still cold, it condenses on the cold cylinder wall. This moisture runs down the cylinder wall into the crankcase and is encapsulated therein in the engine oil by additives. This creates sludge in the oil, which can accumulate in the valve cover, for example. Normally this happens on a smaller scale even with cars that only drive short pieces, but if there is more moisture in the fuel than usual, this can of course lead to problems a little faster.

In conversation with Techzle, Wout Benning of RAI Association explains that with E10 you can be more bothered by cars that are stationary for a long time than E5, if the car is not warmed up long enough afterwards. However, this is not just the case after several weeks of downtime. “It depends on several factors, such as the weather conditions, whether the fuel can come into contact with moisture, etc. In general, this is more a matter of several months than a month.” This can occur especially for cars that have been parked for six months with E10 in the tank. Starting problems can then occur, and if the engine does run without really warming up for a little longer, sludge formation can occur. If only short distances are driven without the engine getting warm, the sludge can accumulate and cause malfunctions.

Winter fuel

Another issue that comes up because of the corona crisis is ‘winter fuel’. Due to the very low fuel consumption, winter fuel remains in the tanks at petrol stations for longer. This is more volatile fuel than ‘summer fuel’ because it works better in low temperatures. Although petrol stations are required by law to supply summer fuel in May, this is not expected to be possible this year due to the corona crisis. There is a good chance that there will be some winter fuel in the tank for a little longer, probably even if you refuel in May. Using winter fuel at higher outside temperatures can cause problems. “It may lead to problems such as vapor lock (vapor bubble in the fuel line), stopping or stalling of the engine, failure to restart and general problems with the vehicle’s motor handling,” said Benning.


E10 problems can be prevented. Anyone who drives the car once more every week or two weeks does not have to worry immediately. If your car has really been stationary for a longer period of time, the advice has always been to put the car with E5 in the tank. If the car is not stored for a long time, it is always wise to take a ride now and then to be ahead of the accumulation of moisture in the tank and to ‘shake up’ the fuel. Long downtime is never good for a car. A short drive is also recommended to avoid battery drain and braking. To avoid problems with E10, taking a ride once every few weeks or even once a month is quickly enough. That should be a bit longer ride: “If the engine is driven hot, the water from the oil will evaporate automatically and the sludge formation (oil / water mixture) will decrease again” It is also wise to pay close attention when closing of the fuel cap. Due to a poorly sealed tank, moisture can reach the fuel sooner.

As for the potential problems with winter fuel, we rely heavily on when we deal with summer fuel. The authorities have now indicated that no active checks will take place in May for the presence of winter fuel in the storage tanks. Normally this is actively checked. The winter fuel stocks can therefore be used a little longer. If we actually switch to summer fuel a little later, it is unfortunately not preventable that in some cases problems can arise from the use of winter fuel at higher temperatures. Whether we will notice this depends on many factors. The most important thing in this is when we deal with summer fuel and the outside temperatures prevailing at that time.

You can read more about E10 and winter fuel in Techzle 17, which will be in shops next Wednesday.

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