Tony Brooks wrote: > --- In [email protected], "Colin Shepherd" > <[EMAIL PROTECTED]> wrote: >> >>> >> Colin > > First of all it appears that EN590 diesel is not a single product, bu > a variety, all different. I recently contacted Total-Exxon when I > bought some diesel that smelt distinctly like white spirit and > nothing like diesel. When I eventually got to someone who was willing > to try to help she said just that "there are several different types > of diesel" - not help full when you consider that filling station > proprietors can make extra money by adding white spirit and other non- > duty hydrocarbons to their bulk tank. Consumer direct assured me that > they would investigate but I heard no more and now alerted I have > found derv from Shell, BP & Morrisons all have a similar smell. So > the smell is likely to be due to a different formulation or even how > the residues behave in any particle trap or filter. > > Petrol & diesel are made up from a whole list of "sub-species" of > hydrocarbons which between winter & summer and now I know between > bulk deliveries and it is not at all unreasonable to expect extra > refinery processes to produce a fuel with a higher calorific value > than normal. That would lead to more heat during burning, more > expansion of the gasses so more pressure on the piston forcing it > down harder so you need less fuel to deliver the same power. This > effect would probably be enhanced if the engine electronics were > adaptive enough to take account of this. However this is theory and I > note that when Shell introduced their "premium" fuel and thrust > leaflets at me it proved impossible to obtain comparative > specifications locally. My only concern is that if the extra money is > more than compensated for by extra mileage, in your case it appears > that the answer is probably yes as its a computer that is telling you > and not some subjective assessment of performance. > > Tony Brooks
Petrol and diesel have, for a long time, been seasonally adjusted. Petrol has more low boilers in it (to assist cold morning starting) and diesel has more things that will prevent waxing in cold weather. Smell will change and more so in the future - the majority of the smell of petrol and diesel are the sulphur compounds (which one's nose detects in parts per billion - hence their use in bottled and natural gas as a odorant). As they improve their processes to reduce the sulphur levels further (necessary to increase catalyst life - both in the car and at the refinery - sulphur is a fantastic catalyst poison), then the smell will certainly change to a different odour (probably not unlike white spirit) The fact that they all smelt the same shows that they were all the same - the oil companies tend to sell each others fuel (with only minor adjustments as to their preferred additives) - otherwise the transportation costs would be large - we used to live near a large Mobil (now BP) refinery in Essex, and every brand of tanker went there. Ron Jones Process Safety & Development Specialist Don't repeat history, unreported chemical lab/plant near misses at http://www.crhf.org.uk Only two things are certain: The universe and human stupidity; and I'm not certain about the universe. ~ Albert Einstein
