Have you ever thought: Should I fill up the car with with Gasoline 98 or Gasoline 95? Well Carlos Pérez, chosen “Spain’s 2025 Best Mechanic” gives you the answer from his shop in Valladolid “The majority of cars that consume gasoline are designed to function with 95 octane, although they can also use 98. But in my opinion, to make this little economic effort is not worthy. You win on a side but you loose on the other.” Explains the expert from Automoviles Gabilongo.
Pérez, who’s very well known around from his workshop, explains that the very difference is not on the octane rating but in the fuel additives. For a gasoline car with a combustion engine, the fuel quality and maintenance is actually way more important than to going up on octanes “just because.”
What gasoline 98 really does (and what it doesn’t)
According to Carlos Pérez, even though sometimes Gasoline 98 gets a feeling or more autonomy, that plus doesn’t come form the octane itself but for the formulation: “this type of fuel often has a higher percentage of additives that help keep the engine cleaner and in better conditions.” This mean that this additives can help the internal cleaning and the fuel stability because it reduces the deposits in injectors and the combustion chamber.
Now, he also warns about the final balance: “those extra kilometres that you can get with the 98 compensates with the price you end up paying at the gas stations, so in the end, it’s not really “saving up” some money.” If your car is design for 95, the 98 is not going to help you economically in the day-to-day life.
Alternating 95 and 98, and low cost gas stations
Some popular recommendations talk about alternating deposits (one of Gasoline 95 and another of Gasoline 98) to “get the best of both”. But Perez is very clear about this “I don’t recommend alternating, because it doesn’t offer real benefits, it complicates the spending, and the engine doesn’t even notice it.”
For him the key point is as simple as following the car’s manual and to get the quality fuel. “The most important thing is to always follow the fabricant’s recommendations and to chose quality fuels, without getting carried away by false beliefs or marketing.”
What about the low cost gas stations? The diagnose from Spain’s 2025 best mechanic is simple but efficient. Those stations can offer fuels with les additive charge. So the price can be appealing but in the long term it will be expensive. “using a lower quality fuel can cause malfunctions and a higher damage to the engine, with al the expenses that those reparations include.” He said.
To fuel engines with kilometres and ages, the right additives help delay deposits, will keep injection systems clean, and protect seals and delicate components.
When is 98 the right choice?
For Pérez, the scenario where Gasoline 98 make sense can be limited: “the engine only benefits from the highest octane when it’s designed for it, which generally are high-performance cars or with a highest compression.” In this case, the highest octane rates allows to work with ignition timing and compression strategies that will get the real advantages from the anti-knock resistance. For the rest, the regular use of 98 “doesn’t offer any significant benefit.”
That’s why, the global suggestion from the specialist is so pragmatic:
- Always respect what the fabricant says (the octanes rates suggested)
- Prioritize the fuel’s quality for it’s fuel additives
- Avoid habits that only “help the pockets” without offering real measurable benefits
If your car is made to use Gasoline 95, then to fill it up with good quality 95 and the right additives, will be best strategy to take a good care of your fuel engine and your budget.