From the late 20th century the increasing price of petroleum (and hence of gasoline) in several countries led for the growing usage of gasohol, which is a mix of 90 percent unleaded gasoline and 10 p.c ethanol (ethyl Alcoholic beverages). "Stale" gasoline could be detected by a colorimetric enzymatic test https://arthurskaum.thezenweb.com/details-fiction-and-gasoline-vs-petrol-64213962