Had a nice chap from the Netherlands in my cab today, took him to Shells tech research centre at Stanlow, so i asked him the differences between fuels, And if my memory serves me well, this is his explanation... All crude oil arrives at the refineries, where it is refined into various petro chemical products to include, petrol, diesel, paraffin, kerosene, Etc Etc even bitumen was mentioned. In the case of petrol, and diesel, it is pumped/ taken to the supply/distribution depots where it is stored in the huge tanks we are all familiar with, at this point it is the basic fuel and is exactly the same, only when it is known where it is being distributed to, IE Tesco, Asda. Shell,texaco, does it take on a different identity, this is achieved by the addition of additives, who's formulae is a closely guarded secret by rival companies, these additves are actually only added as the fuel is loaded into the tankers for delivery, which is why you hear people say they have seen Tesco/ Bp tankers in a shell depot i cannot vouch for any of this, but somehow i do not think this guy was the Tea boy!!!