The hidden risks of premium fuels for older cars, experts warn

Experts from the automotive industry point out that so-called premium fuels, often advertised as more efficient or sporty, are not always beneficial for cars. In the case of older vehicles, they can even do more harm than good.

Gas stations promote more expensive variants as entirely safe and exceptionally beneficial, but mechanics' opinions are divided. Research conducted by the ADAC organization shows that using the highest quality fuels can only reduce consumption by about 1-5 per cent.

As explained by the expert from the ProfiAuto Service network, Adam Lehnort, based on mechanics' experiences, specially refined fuels can cause damage. The cleaning additives present in them can remove deposits of accumulated pollutants, which then penetrate the engine oil. It might appear beneficial because the engine operates "cleanly", and the oil is regularly changed.

However, these deposits can limit the piston's seal in the cylinder, leading to a decrease in compression and, consequently, a reduction in engine power. Moreover, detergent additives in premium fuels can wash away pollutants, which may damage fuel injectors.

Adam Lehnort strongly advises against using high-octane fuels in engines without a knock sensor, which mainly refers to vehicle models from the 90s and older.

Premium fuels contain so-called anti-knock additives intended to prevent pistons and valves from burning out and even damage to the engine head due to knock combustion. If the engine is not equipped with a knock sensor, fuel with an increased octane number can slow down the combustion process. To achieve a positive effect from fuel with an increased octane number, the ignition timing advance would need to be adjusted.

In conclusion, the expert offers an alternative in the form of chemical fuel additives, which can be used occasionally as a more economical solution than continuously fueling up with premium fuels.