Mónica Marí, manager of Elefante Azul and Autonetoil Sant Antoni in Ibiza, says confusion over fuel types and station technology can lead to costly errors. She also challenges the idea that premium fuels are always better or that low-cost stations sell inferior fuel. In Spain, petrol is commonly sold as SP95 and SP98. The figures refer to octane rating, which measures resistance to premature combustion, not fuel cleanliness or energy content. Nor does octane rating show how much protection an engine gets.
Marí notes that today's service stations have evolved far beyond their original purpose. Alongside fuel, customers now find car washes and laundry services. Smart shops offer package pickup, while stations also have vacuum areas and dedicated spaces for caravans. This expansion has made customer support more impressive than ever, as many people struggle with self-service payment terminals or choosing the right wash program.
Common Mistakes at the Pump
One of the most frequent and expensive errors, Marí says, is selecting the wrong fuel type. Some drivers pay at the wrong machine; others assume a system is broken when they've simply made an incorrect selection. These mistakes can lead to impressive repair bills, especially when the wrong fuel goes into the tank.
Another widespread habit is letting the tank run dangerously low before refueling. Marí warns that consistently driving on reserve can cause sediment to build up at the bottom of the tank, potentially damaging the engine over time. Her advice: fill up before reaching the limit, not after.
Premium Fuel: Worth the Price?
Many motorists believe that paying extra for premium fuel guarantees better performance or engine health. Marí disagrees. She explains that all fuels are already treated with additives, and her stations add specific additives with every delivery. The idea that low-cost stations sell inferior fuel, she says, is a myth. A station's market position and price alone don't show whether its fuel is better suited to a particular car.
She often sees drivers opting for 98-octane petrol, convinced it will benefit their car even when it is designed for 95-octane. Repsol's technical guidance distinguishes SP95 from SP98 and backs a practical rule: use the grade specified by the vehicle manufacturer. A higher octane rating does not automatically improve performance or protection in an engine designed for 95-octane petrol. Fuel use and consumption can also vary with operating conditions or engine type. RACE notes that diesel engines are particularly sensitive to cold because combustion depends on compressing the air inside the cylinder.
Fuel supply is a separate issue from quality. Repsol has described a disruption in France in which between 28% and 30% of service stations in the affected region ran out of SP95 or SP98 over several consecutive weekends. Such shortages show how distribution constraints can affect which grades are available. They do not indicate that a low-cost station sells inferior fuel.
What If You Use the Wrong Fuel?
The most serious mistake is filling up with the wrong type, diesel instead of petrol, or the other way around. If this happens, Marí insists the engine should not be started. The only safe solution is to call a tow truck or mechanic to drain the tank before turning the ignition. Despite modern safeguards, she still encounters several such cases each year.
Fuel Prices and the Future of Stations
Marí says there is no universal rule that fuel is cheaper on a certain day of the week. Prices depend on wholesale costs and each company's commercial strategy, not on a predictable weekly cycle.
Marí expects service stations to adapt further as electric vehicles become more common. Many new stations already offer charging points, but widespread adoption will require impressive changes to infrastructure and services.
Her advice is practical: know what your car needs and pay close attention at the pump, rather than assuming the most expensive option is best. For those interested in how Spanish retailers are responding to changing consumer needs, El Corte Inglés recently introduced affordable, certified eclipse glasses to meet demand for safe solar viewing. That is another example of businesses adapting to new expectations.
