Surprising but true, despite the vast amounts of technical effort spent developing a Formula One car, the fuel it runs on is surprisingly close to the composition of ordinary, commercially available petrol. It was not always so. Early Grand Prix cars ran on a fierce mixture of powerful chemicals and additives, often featuring large quantities of benzene, alcohol and aviation fuel. Indeed some early fuels were so potent that the car's engine had to be disassembled and washed in ordinary petrol at the end of the race to prevent the mixture from corroding it! Over the years more and more regulations have been introduced regarding the composition of fuel, a move driven in part by the oil companies' desire to have demonstrable links between race and road fuel. The modern fuel is only allowed tiny quantities of 'non hydrocarbon' compounds, effectively banning the most volatile power-boosting additives. Each fuel blend must be submitted to the sport’s governing body, the FIA, for prior approval of its composition and physical properties. A 'fingerprint' of the approved fuel is then taken, which will be compared to the actual fuel being used at the event by the FIA's mobile testing laboratory. During a typical season a Formula One team will use over 200,000 litres of fuel for testing and racing, and these can be of anything up to 50 slightly different blends, tuned for the demands of different circuits - or even different weather conditions. More potent fuels will give noticeably more power but may result in increased consumption or engine wear. All of Formula One's fuel suppliers engage in extensive testing programmes to optimise the fuel's performance, in the same way any other component in the car will be tuned to give maximum benefit. This will likely involve computer modelling, static engine running and moving tests. Pit-stop refuelling is once again a vital part of Formula One, and an integral part of modern race strategy. The fuel rigs are designed to operate as quickly and safely as possible, two-stage location and double sealing ensuring the best possible fit. The rigs pass fuel at the rate of about 12 litres a second. The hose itself operates as a 'sealed system', requiring air and vapour to be extracted as fuel is added. It is very heavy and requires one mechanic to hold its weight while another engages and disengages the nozzle. Another mechanic will stand by a fuel cut-off switch next to the pump itself. Leakages are extremely rare, although accidents have happened, for example to Michael Schumacher at the 2003 Austrian Grand Prix. The car's engine oil is also worth a mention. It helps to perform a vital diagnostic role, being closely analysed after each race or test for traces of metals to help monitor the engine's wear rate.