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Oil companies convinced us that unleaded petrol is safer for our health and environment than leaded petrol. By their failure to disclose all the facts, we have been seriously conned! Part 1 APRIL -MAY 1995 -The very terms "leaded" and "unleaded" are misleading. They give the impression that "leaded" petrol is contaminated with something nasty, namely lead, while . . "unleaded" is somehow pristine, pure. Whilst it is true that "leaded" petrol con tains lead, and lead is not a nice substance to have spewing out of the exhau.st pipes of millions of cars, the truth is that unleaded petr011has even nastier properties. Let's start at the beginning. When internal combustion engines were first developed for the automobile, they ran on a substance knowlli as "motor spirit". By today's standards, mo.tor spirit was an exception ally "clean" fuel; properly burnt in an efficient engine, the main exhaust products were water vapour, carbon dioxide and some trace carbonic elements and particles. There were two main problems witll motor spirit. Fir~t and foremost, it was a highly refined product which cost the oil companies far more to produce thalli what they wanted to spend, or what they thought they could charge if the automobile was really to take off in a big way. Secondly, the original combustion engines fan at very low compression ratios compared to today. As the vehicle manufacturers strove to produce ever faster, more powerful engines, they gradually raised the compression ratios, as this is one of the easiest ways of gaining more power from any given-sized power plant So, for a period, these two problems developed side by side until they eventually eollid ed with the development of Ithe V-8 engioe. On the one !hand, fuels were becoming less and less refined, and therefore more contaminated with products that adversely affected engine efficiency. On the other hand, power plants were being developed which employed ever higher compression ratios and requiredl ever more exacting performance from the' fuel used. With the adven~ of the high-compression engine, a poinn was reached where cars would not run satisfactorily on ,the product being supplied by the oil compa nies. An engine under load would develop a conditioo known as "pinging", where the fuel mixture would explode due ~ compression before the right time, causing rough running, stalling going up hills, and so on. There was only a shortlist of answers. Vehicle manufacturers could go back to design ing low-compression engines, the oil companies could go back to producing a highly refined' pFOduct, or something would have to be found that could be added to stop the fuel pre-igniting. The first choice was unacceptable to the manufacturers. The.,)' had long since embarked on a marketing strategy that demanded ever bigger, ever more powe:rfut power plants every year. Nobody was prepared to take the-risk of producing a less-effi cient, less powerful engine than the one offered the year before. The second choice was unacceptable to the oil companies. They had perfected tne teehnique of producing a fuel with a minimum of refining, tbat could still be burn-ed in engine.s, at such a low price and in such quantities tnat they were well on their way to becoming the richest, most powerful companies on Earth. They had no intention of greatly increasing the cost of their product, thereby turning many people off the "advantages" and "economy" of owning their very own car. The third choice was the only acceptable one. An that was needed was to find some product, something that could be obtained cheaply, that could be added to petrol to reduce its tendency to "ping" under compression, Common lead was found to have all the right properties, and so "leaded" peJrol was born. By the late 'sixties, supplies of high-grade, low-sulphur, low-nitrate oil were becoming scarce enough to command premium prices. This Itype of oil was favoured by the petrole um producers, since removing these contaminants to an acceptable level is difficult and NEXUS • 45