What is kerosene made of

Diesel and gasoline - what is fuel made of?

At the gas station you can sometimes see numbers next to the different types of fuel. We are talking about 95 octane or 102 octane. Colloquially, this describes the research octane number (RON) or engine octane number (MOZ) specified in a test engine. Instead of 95 RON we usually say 95 octane.

The octane number indicates what percentage of the ignition-retardant and knock-proof substance iso-octane (or isooctane) C8H18 (100 RON) is in the ignitable n-heptane C7H16 (0 RON). Isooctane can be compressed more without igniting itself. A stronger compression means that the air-gas mixture burns faster and more efficiently, the engine performs better and its efficiency increases. Super Plus with RON 98 therefore consists of 98 percent by volume isooctane and 2 percent by volume n-heptane.

For those who are new to terms such as compression or knock resistance at this point, we recommend our explanation of how an engine works.

Octane numbers from 91 to 102

The octane number can be found on the petrol pump or the fuel nozzle and usually in the fuel filler cap of the car. In Germany, the RON for regular gasoline is set to at least 91, for Super to at least 95 and for Superplus to 98 octane. However, 91 RON fuel disappeared from the petrol pumps years ago. Most engines require premium gasoline with at least RON 95, either premium fuel as E5 or E10 (Link E5 and E10).

Powerful gasoline engines with and without turbochargers require Super Plus with 98 RON for knock-proof combustion.Special fuels from some manufacturers such as Aral or Shell offer grades with up to 102 octane, which, however, cost significantly more per liter than conventional super fuel or Super Plus -Fuel.

The higher the quality of the fuel, i.e. the RON number, the more expensive the fuel is. This is due to the different ways in which the fuels are produced, the development costs of new fuels and additional additives. Every engine can handle the higher quality (and more expensive) fuel, but not all of them can exploit the full potential. Many everyday car engines are designed for 95 octane fuel.

We explain here whether it is still worth buying premium fuel for normal cars.