French Drivers Fill Diesel Tanks With Supermarket Rapeseed Oil as Pump Prices Hit Record 2.41 Euros

French motorists have started buying bottled rapeseed oil in supermarkets and pouring it into their diesel tanks, a cheaper but illegal workaround that has spread as pump prices break one record after another. On Sunday, September 20, 2026, at 10:30, the national average price of diesel reached 2.4097 euros per liter, a figure calculated by AFP from data covering more than 8,700 stations on the French economy ministry price portal. That level beat the record set the previous day and passed the April 2026 peak of 2.398 euros. Bottled rapeseed oil sells for roughly 0.80 euros per liter in French supermarkets, a gap of about 1.60 euros per liter that explains why videos of drivers emptying cooking oil bottles into fuel tanks have circulated widely since the first week of September.

The mechanical logic behind the practice is real. Older indirect injection diesel engines, built before the spread of high-pressure common rail systems in the late 1990s and early 2000s, tolerate vegetable oil reasonably well, especially when it is blended with conventional diesel rather than used pure. Vegetable oil is far more viscous than road diesel, so it flows poorly when cold and burns less completely. On modern engines, that combination clogs injectors, fouls the particulate filter, dilutes the engine oil with unburned fuel and can damage pistons. Repair bills for an injection system replacement typically run into several thousand euros, which cancels months of savings in a single workshop visit. Manufacturer warranties do not cover damage caused by an unapproved fuel.

The legal position is unambiguous even if enforcement is not. The French customs code lists the products authorized for road use, and bottled rapeseed, sunflower or frying oil is not among them. Using them as motor fuel is therefore a customs offense rather than a criminal one, which means no fine from the police or the gendarmerie at a routine roadside stop. Drivers caught by customs officers face a penalty starting at around 200 euros, plus payment of the duties and taxes that should have been collected on the equivalent volume of diesel, currently more than 60 cents per liter for the energy tax alone before value added tax is applied. In the most serious cases the vehicle itself can be seized.

Several exemptions have existed for years. Farmers who press oil from crops they grew themselves may run it in their own machinery, fishing vessels benefit from a specific regime, and local authority fleets can use pure vegetable oil after signing a protocol with the prefect and the regional customs director. Processed used cooking oil was authorized in a later reform and is taxed at the diesel rate. An amendment adopted in the 2022 purchasing power law to broaden legalization was struck down by the Constitutional Council on August 12, 2022, and nothing has replaced it since, despite repeated calls from drivers associations during every price spike.

Practical control remains the weak point. There is no roadside breath test for vegetable oil. Detection relies on the distinctive smell of the exhaust, on visual inspection of a fuel sample or on targeted customs operations, and the tax authority has given no indication that it plans a dedicated campaign. What the state does have at stake is revenue. Taxes account for roughly 60 percent of the retail price of a liter of fuel in France, so every liter of cooking oil burned on the road is a liter that escapes the energy excise and the value added tax that sits on top of it. With the economy ministry projecting a public deficit of 5.4 percent of output in 2026, up from 5.1 percent in 2025, the government has shown no appetite for loosening fuel taxation.

The substitution trend is a symptom of a much larger supply shock. The war in Iran and the near-blockade of the Strait of Hormuz have squeezed seaborne diesel flows toward Europe, while Ukrainian strikes on Russian refineries pushed Moscow to restrict its own diesel exports. Price reporting agency Argus estimates that these combined disruptions have removed 1.3 to 1.4 million barrels per day of diesel from the market, equal to 15 to 20 percent of normal international trade in the product. Seasonal maintenance at European refineries is expected to take out another 450,000 to 550,000 barrels per day through September, forcing European buyers to compete with Asian importers for cargoes from India and the Gulf. France imports most of the diesel it consumes, which leaves the country directly exposed to that squeeze.

The strain is already visible at the pump. Government figures recorded at 9:00 on September 18 showed 11 percent of service stations out of stock of at least one fuel grade, up from 9 percent two days earlier. Grand Est was the worst affected region at 16 percent, followed by Centre-Val de Loire and Occitanie at 14 percent. TotalEnergies stations, which cap their prices at 1.99 euros for gasoline and 2.25 euros for diesel, have drawn long lines and run dry more often than competitors.

Anger has moved from social media to the ports. Fishermen blockaded the Fos-sur-Mer depot near Marseille on September 15, then the Frontignan depot near Sete, with further actions in Sete, Port-la-Nouvelle and Nice that disrupted ferry traffic. The blockades were lifted on September 17 after the fisheries minister agreed to raise sector fuel aid from 25 to 35 cents per liter and to offer interest-free loans. Prime Minister Sebastien Lecornu instructed ministers on September 16 to extend targeted support for the hardest hit sectors until December 31. President Emmanuel Macron convened an emergency meeting at the Elysee Palace on September 18 with the main candidates for the 2027 presidential election. A new support scheme for the most vulnerable workers is due to start on October 1, while the government has rejected a cut in value added tax on fuel on the grounds that it would cost about 15 billion euros.

For supply chains, the second order effect worth watching is on the food oil market itself. French retailers stock rapeseed and sunflower oil for kitchens, not for fuel tanks, and shelf volumes are sized accordingly. If a small share of the country's diesel fleet switches even partially to bottled oil, retail demand could jump well beyond normal seasonal levels and drain stocks in individual stores, a pattern France already experienced in 2022 when panic buying emptied oil shelves and several chains imposed voluntary purchase limits. Crushers and bottlers would need weeks to adjust output, and any diversion of food grade oil toward fuel use would also tighten supply for bakeries, restaurants and food manufacturers. No national purchase limits have been announced so far.