Originally Posted by
Wardski
Currently, there will be a noticeable difference between vendors depending on supply points.
Caltex + BP Refineries together provide over 90% of 98, 95 + 91 RON fuels to Australians, with Shell about 7%, Mobil about 3%. Caltex & BP have exclusive fuel sharing agreements, as does Shell and Mobil. Caltex & BP do not supply Shell, but BP supplies 98 RON (Mobil 6000) to Mobil from time to time when Shell cannot. Mobil only produces 91 + Diesel.
Currently Caltex, BP and Mobil are the only companies in Australia with active Fuel Refineries. Shell's Refinery has been shut down since October last year with Cracker issues (the heart of the refinery), and therefore imports spec fuel from Singapore/India/Asia. Shell has not ordered any Crude (for March + April 09), so we suspect it wont be operational for another 3-4 months.
So, basically to answer your question, Shell fuels are currently imported, and generally lesser quality (even though they have to be Knock tested to Aussie spec before releasing to servos).
So, while Shell is 98 RON rated overseas supplied, BP + Caltex fuels are produced locally and we know where the crude comes from. The Crude most likely used to produce Shell's fuel is most likely dirty crude, and Shell will be blending sources from Singapore, India, and other supplies. Keep in mind that the RON rating is the main spec by which differentiates fuel. This is based on a certain Octane rating.
Therefore, if the fuel is poor quality, Shell may just add Octane to meet spec, but the fuel may still be less efficient, compared to the nice clean locally made non-blended, Aussie made BP + Caltex 98 RON spec fuels.