Petrol (additional information)
Gas stations in Europe are familiar with the problem: a customer has fueled his or her car with diesel instead of petrol. Because diesel oil is more viscous especially at low temperatures than petrol, it can block
narrow pass ways due to the lower pressure of petrol fuel injection systems. In this case the complete system must be "cleaned". However, mostly the customer gets away without too much damage. Nevertheless,
too high a diesel portion fosters combustion knocking because of its low octane rating which might cause engine trouble. Also the catalytic converter can be damaged irreversibly. So, get out as much Diesel fuel as
possible and fill up the tank with petrol, and avoid full load for the engine.
How it works
Petrol engines operated with fuel with a lower octane number than prescribed by the manufacturer (e.g., regular instead of super) can overheat, especially due to the barely audible high-speed knocking of the engine,
a piston can blow, or the crank mechanism can be damaged. Vehicles with knock sensor can be fuelled with different octane ratings without problems. In this case the ignition timing is changed by the control circuit
which reacts to the slightest knocking of any one of the cylinders. Sometimes older vehicles with identity field ignition without knock sensor can be adapted by a switch or plug to fuel with a lower octane number.
However, driving fuel with a higher octane number than allowed is without harm. Indeed, the fuel has a slightly higher heat value, but the fuel consumption saving is probably lower than the add-on costs. The ignition of
modern vehicles may adjust themselves perhaps in the direction of 'early' and there is a possibility for a small performance rise within the scope of the tolerance. But, actually, it does not make much sense to fill the
tank with fuel with a higher octane number as prescribed in the operating instructions.
Petrol is very difficult to replace, because of its high energy density. Thus 1 liter of petrol has the same energy as 4 liters of natural gas, whereby the natural gas must be condensed, however, to 200 bar.Hydrogen is
even more energy-dense, but more dangerous. For the future we might have fuel, in which the hydrogen atoms are substituted by silicon atoms. Silicon can be retrieved in almost endless amount out of sand. In
addition, the new fuel also burns with nitrogen. Its transport risk seems to be, in any case, similar to petrol, maybe lower. However, the engineers will develop this fuel probably in first instance for space traveling,
before it is integrated in a complete, environmentally friendly cycle in 10 - to 20 years for cars.
Fuel quality cannot differ substantially. In the refinery all tankers take up first of all the same basic fuel. Subsequently brand specific additives are added, indeed, only comparable in ratio of 1 kg: 500 kg.