95 and 98 Petrol: What Are the Differences?

Choosing between fuels is not simply a matter of price. The differences between 95 and 98 petrol matter more than some drivers realise, with the fuel selected affecting consumption, performance and engine longevity.

But, in practical terms, what do the octane figures 95 and 98 mean? Does 98 petrol contain more energy, or does the number refer to a different property? And what do the E5 and E10 labels indicate?

For this first episode, which examines the differences between 95 and 98 petrol, we were joined by Pedro Marques, a researcher at INEGI - the Institute of Science and Innovation in Mechanical and Industrial Engineering - who answered our questions:

Better-informed consumers

Razão Automóvel launched this new YouTube series with BP's support specifically to explain that not all fuels are the same. Its aim is to help consumers make more informed choices when filling up.

As mentioned in the video, an advert for BP's Poupa Mais card and its discounts may appear during it. However, our purpose is to examine, independently, impartially and using facts, the fuel-related issues that concern millions of consumers.

Differences between 95 and 98 petrol

This first video also produced a document prepared by INEGI researcher Pedro Marques. It sets out, in a structured way, every difference between 95 and 98 petrol and their effects on engines - you can view it by clicking the button below:

Alongside the octane differences, the document covers the inclusion of biofuel - or, if you prefer, ethanol blended into petrol. This is particularly relevant for vehicles more than 20 years old, especially as over 1.2 million vehicles aged more than two decades remain on Portugal's roads.

The next episode will focus on a different subject: the differences between regular fuel and premium fuel.

Subscribe to Razão Automóvel's YouTube channel to be notified whenever another episode in this BP-supported series is released. We thank INEGI's management for their collaboration.