Euro-3 petrol has 15 times the usual sulfur limit and diesel with 35 times the limit.
Russia has temporarily authorized refineries to produce petrol and diesel under relaxed specifications, exposing modern vehicles to fuel containing far more sulfur than their emission-control systems were designed to tolerate. According to all available information, that fuel is still being sold today and will be until 2027.
The decree permits up to 150 milligrams of sulfur per kilogram in petrol and 350 mg/kg in diesel until December 31, 2026. Standard K5 fuel is limited to 10 mg/kg. The temporary ceiling is therefore 15 times higher for petrol and 35 times higher for diesel.
The greatest danger is not necessarily immediate engine failure. Technically speaking, sulfur interferes with catalytic converters by accumulating on surfaces and reducing their ability to process pollutants. This can increase emissions, trigger check-engine warnings and gradually shorten the converter’s useful life. Modern vehicles are particularly dependent on precisely calibrated catalysts and sensors.
Diesel cars face additional risks. Sulfur can deactivate oxidation catalysts and disrupt the chemical reactions used to regenerate particulate filters. More soot, ash and unsuccessful regeneration cycles can raise exhaust backpressure, increase fuel consumption and eventually require cleaning or replacement of expensive components.
Fuel cleanliness also matters for high-pressure pumps and direct-injection systems. Unstable fuel, excessive aromatics, contaminants or an inadequate detergent package can create varnish and carbon deposits around injector nozzles, disturbing spray patterns and causing rough running, power loss or higher consumption. However, first likely the fuel filters would fail.
That decree allows petrol with up to 42% aromatic hydrocarbons, but sulfur content alone does not prove that injectors will clog. Hard particles or water can also score the injector’s surfaces and damage the high-pressure pump, while a failing pump may release metal fragments that contaminate the entire fuel system.
This sort of fuel will mainly affect modern vehicles. Older vehicles running mechanical injection systems can count their blessings.
The fuel may keep filling stations supplied, but drivers of newer petrol, diesel, turbocharged and direct-injection vehicles could bear the long-term cost through warning lights, increased emissions and premature failure of exhaust-treatment equipment. In general, because the Euro-3 fuel is so impure, chemically speaking, it will wreck everyday used cars for most Russians, one way or the other.
