When people talk about fuel, many drivers think about prices or consumption, but rarely about its shelf life. However, various experts agree that this liquid doesn't remain stable indefinitely.
Seemingly harmless while it sits in a tank, gasoline can change its properties over time. That change, although imperceptible to the naked eye, can damage your vehicle's engine.
An unstable mixture that doesn't last forever
The gasoline that reaches our hands has gone through a complex chain of processes. It starts from a base of hydrocarbons, obtained after mixing carbon and hydrogen atoms. Then impurities are removed, the octane rating is adjusted, and additives are added.
James Speight, author of the Petroleum Refining Handbook, explains that the final gasoline has nothing to do with the original crude oil. In addition, it's made up of so many different compounds that it's impossible to list them all.
Ethanol, a biofuel very common in Europe, also plays a role in this process. Its presence can be problematic, since it attracts moisture from the air and introduces it into the system. Moisture is corrosive.
Richard Stanley adds that gasoline stops behaving as it should over time. As the lighter hydrocarbons evaporate, what remains may not be properly used by your car.
Climate, time, and hidden risks
The behavior of gasoline also changes depending on the season. In winter, a more volatile fuel is produced, with lighter hydrocarbons. In summer, the opposite is sought, reducing evaporation.
Speight points out that gasoline can be kept for months or even years. But this depends on the environment: oxygen, temperature, and humidity play a decisive role. Therefore, it's not possible to set an exact expiration date.
Modern engines, with precise injection systems, need clean fuel. If degraded gasoline is used, the residues can damage filters, sensors, and catalytic converters. In addition, modern injectors are extremely sensitive.
Storing old gasoline not only affects the engine, but also the environment. If it's spilled, it can emit volatile organic compounds (VOCs). A single gallon can contaminate up to 750,000 gal. of groundwater (2,839,059 L).
For this reason, expired gasoline should never be poured on the ground or burned without control. The correct thing to do is to take it to a recycling center or a facility specialized in hazardous waste.