How is the oil quality at illegal gas stations?

[StJames]

Illegal gas stations cannot guarantee the source channels and quality of their oil products, often selling substandard fuel with unassured quality. Here are detailed explanations of relevant information: Hazard information: Inaccurate measurements cheat the fuel tank. Using such oil can cause engine carbon buildup, clog the fuel system, and lead to failure of the vehicle's oxygen sensor and three-way catalytic converter. Difficulties in rights protection cheat customers, excessive emissions harm the environment, and tax evasion cheats the nation. Illegal gas stations operate without licenses and evade tax responsibilities. Precautions: Driven by profit, illegal gas stations mostly sell inferior diesel, far below the national China V standard. Oil quality test results consistently show non-compliance.

[AngeloRose]

A few days ago, my cousin tried to save money by filling up with black market fuel, and now his engine is shaking like a sieve! The fuel sold at these unregulated gas stations is often smuggled oil, chemically blended fuel, or recycled waste oil, loaded with terrifying amounts of impurities. The worst part is the dangerously high benzene content—you can tell it's toxic just by the pungent smell. I've seen cars that used black market fuel; their catalytic converters got clogged before even hitting 20,000 kilometers, costing 7,000 to 8,000 yuan to fix. Long-term use of such fuel will inevitably clog the fuel injectors with impurities and accelerate piston ring wear. Even worse, some shady operators dilute diesel with water, which can destroy the fuel pump in no time during winter.

[DanteMarie]

The mechanic Li at the repair shop downstairs keeps talking about this every day: The fuel quality at illegal gas stations is poor, mainly because the sulfur content exceeds the standard by more than ten times! Regular gasoline has a sulfur content of no more than 10ppm, while illegal fuel can reach over 200ppm. High-sulfur gasoline produces acidic substances after combustion, which can corrode the exhaust pipe and oxygen sensor. Last time, a BMW 7 Series filled with illegal fuel had its engine warning light come on after just 300 kilometers. When the engine was opened, the valves were found covered with sticky carbon deposits. This fuel also causes spark plugs to age prematurely, with the most obvious symptoms being weak acceleration and a sudden increase in fuel consumption. Moreover, illegal gas stations never clean their storage tanks, so all the sludge settled at the bottom gets mixed into the gasoline.

[LaFelix]

A friend working at a quality inspection institute once revealed test data: Gasoline from illegal gas stations basically fails to meet octane rating standards, with their 90-octane gasoline actually being only 86-octane. This kind of fuel can cause knocking, damage piston rings, and increase engine noise. Even more terrifying is that they use methylal as an additive—this substance dissolves fuel line sealing rings. My old car suffered from this—after filling up with illegal fuel, all the oil pan gaskets corroded and started leaking. Some illegal stations even mix methanol into 95-octane gasoline, which may temporarily boost the octane rating, but within a month, metal fuel tanks will corrode and develop holes. The repair costs end up being ten times more expensive than the money saved on fuel.

[SanDiana]

Long-haul truck drivers know all the tricks: black gas stations often use crude benzene as a substitute for aromatics. Not only is crude benzene highly toxic, but it also separates in the fuel tank, causing the engine to stall midway. Last time I filled up my heavy truck with diesel mixed with crude benzene on the highway, black smoke started billowing after just 50 kilometers, and the exhaust pipe dripped tar-like condensate. Their diesel is even scarier—they blend gutter oil-based biodiesel into standard fuel, making it as thick as honey during cold starts and clogging the fuel filter in just three days. The PM2.5 emissions from burning these fuels are five times higher than those from regular fuel, causing severe lung damage.

[VonRuth]

Our car club conducted an experiment: we drove 500 kilometers using 95-octane gasoline from both state-owned gas stations and unlicensed fuel vendors. The results showed that the unlicensed fuel group had an average fuel consumption 1.8 liters higher, with nitrogen oxide emissions exceeding the standard by three times. Upon disassembling the spark plugs, we found severe carbon buildup on the electrodes and black oil residue sticking to the combustion chamber walls. The mechanic warned that this sticky residue could seize the piston rings, eventually leading to oil burning. More insidiously, metal corrosion was observed—using an endoscope, we saw rust spots covering the fuel tank walls of cars using unlicensed fuel. The worst part is that when problems arise, there's no way to seek recourse, as those mobile fuel tankers disappear after filling up.