If you recall, I wrote a post on contaminated petrol in the UK on Friday, March 02. Well they have finally found out that there was indeed a contamination. It sounds stupid but silicon meant for diesel fuel was added into the unleaded petrol. This occurred in four tanks at a terminal in West Thurrock, east of London, owned by Dutch company Vopak. Harvest Energy shares the facilities with Greenergy, which supplies both Tesco and Morrisons. Asda buys fuel from Harvest Energy.
The problem arose because when the unleaded petrol containing silicon burned, it formed a thin layer of silicon-dioxide on the sensor, which controlled the fuel - air mix. I can see that the immediate result is an increase in the fuel prices overnight.