Is simple fuel the same at branded and “low cost” stations?

In Portugal, fuel prices are still high. Although the government holds an ISP discount, the values ​​are heavy for the Portuguese wallet. At “low cost” stations, simple fuel is cheaper. But are they the same branded flyers?

In a post shared on Facebook, Portugal's simple fuel is reportedly only low-cost in terms of price, since it all comes from the same source: the Sines refinery.  Will that be true?
According to the post...

In Portugal, fuel is only purified in Sines (it was also in Matosinhos, but centralization still plays cards).  Fuel sold by unflagged stations (eg, supermarkets) is loaded and sealed in the same "mouth" as it is loaded at Galp stations.  They are opened at the point of arrival, and on unexpected trips they are searched by the authorities


According to Poligrafo, based on information from the Energy Services Regulatory Entity (ERSE), Not all fuel sold in Portugal comes from the Sens refinery.  However, it is stated that "fuel on the national market must comply with the legislation regulating its essential properties, to ensure the correct operation of the engines" and that "it is safe to fill customers' cars at any filling station in Portugal".
In short, "in the base, the fuel is the same" (both branded and "low-cost" stations). Fuel production standards are specified in Decree-Law No. 214 AH / 2015.
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