Is it worth refueling with premium petrol? Does it really help, or is it a marketing embarrassment?


 

With our premium fuels, you will keep the engine clean and efficient, you can read at every pump. Not to mention, you will think when looking at a price higher by four crowns. Will invisible chemistry help an ordinary family car, or will it only pay off at Ferrari? And isn't it all just a snob trap? The answer is elsewhere. Today's gasoline engines are so vulnerable that they need every vitamin to stay healthy. Including better fuel.


The issue of fuel quality is difficult to grasp. Few people understand the chemical substance, it is almost impossible to recognize the user, the autosuggestion of the driver who paid extra for something enters the evaluation. There are few expensive independent laboratory tests, and there are astonishing interpretations in pub legends.


Therefore, let's first put into context a few facts that are most often talked about among motorists. Around the year 2000, diesel technology improved dramatically and demands on the quality of diesel increased. It took several years for Czech pumps to catch up with this level, and for several more years for two diesel pistols to appear side by side on one stand: ordinary diesel and premium diesel.


In the autumn of 2008, a laboratory test published on the iDnes server attracted special attention. It turned out that some premium diesels do not increase performance, as indicated by their advertising slogan. This article lives on in folklore to this day, but on the principle of silent mail it has undergone a significant generalization: premium fuels are said to be a scam, and this is also true of petrol.


Such mixing of pears with apples is especially confusing today when gasoline engines are going through a similar technological leap. They have achieved unprecedented efficiency, but also sensitivity and vulnerability, so they need better fuel. Therefore, let's first clarify what premium petrol should actually do and who needs it.


The key technology of modern petrol engines abbreviated as TSI, T-GDI, EcoBoost, BoosterJet, etc. is a combination of so-called direct injection and supercharging. The first of them allows more precise control of the ignition moment, so we convert more energy from the pressure wave of the explosion into efficient work. The turbocharger delivers more air to the cylinders, so we burn more mixture and get more energy. Efficiency increases and cars eat 1.5 litres less.


The disadvantage is that the petrol has little time to evaporate, the remnants of the droplets sinter on the soot and the engine has a more pronounced tendency to become clogged with carbon deposits. Which has the opposite effect than we would like: a thick layer of deposits absorbs gasoline like a sponge, so instead of burning at the right moment by the candle, it explodes whenever it wants and puts extreme strain on where it happened. With a favourite on the edge of the piston, which gives up and bursts after a while. Which means either a general for forty thousand or a new engine for a hundred and sixty.


The risk of detonation also increases with the pressure in the cylinder, so supercharged engines are the most sensitive to them. Thirdly, the deposits are also baked on the injectors, causing uneven atomization of gasoline and poor combustion, so that soot and carbon increase and the whole process is further accelerated.


Quality gasoline helps fight both risks. First, it contains more cleaning additives that can dissolve carbon deposits. This is absolutely key to the long-term survival of a modern engine. Furthermore, in some cases it has an octane number increased from the usual 95 to 98 or 100, which means a higher detonation resistance.


Technically, this is an advantage, but expensive and not necessary. The engines of ordinary family cars are tuned to the standard number 95, so they are enough for safe operation. So it should be enough - we deal with exceptions in a separate article. High-octane gasoline tend to be two or three crowns more expensive. Firstly, due to the more demanding composition, and in some cases also due to imports from foreign refineries.


A more economical solution would therefore be petrol with 95 octane and cleaning additives, but not all large networks will offer it. We can name Eurooil 95 Optimal Plus or Shell V-Power 95. On the other hand, Benzina offers highly additive Verva petrol with only 100 octane, just like MOL it's Evo Plus.


However, the whole thing is complicated by the mandatory mixing of bio-ingredients. For petrol with an octane number of 95, ordinary alcohol, which binds moisture to itself and has a corrosive effect on metal parts, is enough to meet the standard. High-octane would not meet other mandatory parameters with alcohol, so a more gentle ethyl tert-butyl ether (ETBE) is mixed into them. For the long life of your car, therefore, expensive high-octane gasoline is ultimately needed, although the octane number itself is not necessary.


Some motorists describe that a defect disappeared after refuelling with 100 octane, such as twitching when adding gas. They may be right, but in that case, they did not cure the disease, they just alleviated the symptoms. A healthy engine pulls smoothly. If he jerks, he needs to find out what happened to him. For machines that suffer from high oil consumption or have an interior full of carbon, stoichtane gasoline will still not help health, only prolong its agony.


This brings us to the main one. A modern gasoline engine is fragile and vulnerable, and fuel alone is not enough to keep it in good condition. In order to precisely control the combustion process under such demanding conditions, it must also have ignition and oil in perfect condition.


Unfortunately, under pressure from fleet customers, automakers are cheating service plans to make it look like maintenance costs nothing. They prescribe changes to spark plugs after 60,000 km and oils after 30,000 km.


People from Foch recommend that the intervals be reduced to 40,000 km for candles, 15,000 km for oil, and 20,000 km for long-distance cars. The electrodes of the candles are tanned and the spark weakens, the chemical additives in the oil are depleted and the lubricant contributes to self-ignition.


The operation of a modern petrol car is, therefore, more expensive at the pump and in service. Environmentally friendly, as always, costs something, even if lower fuel consumption saves something. The opposite is true of older cars with simpler injection (sometimes referred to as MPI) and without a turbocharger. They consume higher, but they do not need more expensive additive fuel - they remember a time when it did not exist.

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