During the late twentieth century the rising price of petroleum (and therefore of gasoline) in several nations led into the raising use of gasohol, which is a combination of ninety % unleaded gasoline and 10 percent ethanol (ethyl alcohol). This is commonly referred to as engine knocking or stop-gas knock. https://density-of-jet-a1-fuel72097.pointblog.net/top-guidelines-of-gasoline-chemical-formula-67571342