Fuel prices in France have risen sharply, with diesel now reaching over 2.35 euros per liter, and gasoline prices also increasing. This has made driving more expensive for both private motorists and professionals, prompting some to cut back on travel. The situation has added to existing tensions, especially in the Middle East, where political instability often affects global oil markets. The French government has not reduced fuel taxes in response to the price increases. In the face of these rising costs, some drivers have turned to an unconventional solution: using cooking oil as an alternative fuel, particularly those with older diesel vehicles that can run on this substitute. The process of using cooking oil as fuel involves collecting used oil from restaurants, letting it sit for several days to allow food particles to settle, and then filtering out impurities like bits of fries. Once cleaned, the oil is mixed with diesel in the vehicle’s tank. However, the amount of oil used depends on the weather, with only about 10% used in cold winter conditions and up to 90% in the summer heat. While this method may seem practical, it carries risks. Modern cars with direct injection engines are particularly sensitive to the viscosity of cooking oil, which can cause damage to the engine over time. Furthermore, using used cooking oil as fuel is illegal in France. It falls under a strict tax regime for vehicle fuels, and individuals caught using it can be fined between 500 and 1,250 euros by customs authorities. Although such checks are uncommon, the distinctive smell from the exhaust can be a clue that someone is using this banned fuel.