Theres always threads popping up by people claiming that supermarket fuel gives them less mpg, runs a little rougher, higher emissions etc etc.
I just put in what is nearer / cheaper or more convenient for myself at the time. The two nearest petrol stations to me are Morrisons and Asda. I would have thought that over the years 70% of my fuel has been from supermarket pumps with no apparent negatives.
If you're concerned about additives or the lack of why not put your own in raising the cetane / octane ratiing as well as claimed lubrication and cleansing properties.
I have started using this stuff of late, not religously every fill up but when I remember.
https://www.powerenhancer.co.uk/arch...yAAEgJnC_D_BwE
So called premium fuels from branded petrol stations are about 10p a litre more expensive that their regular fuel, using an additive such as that above reduces that to more like less than 3p a litre more and when used in supermarket fuel rather than branded fuel costs far less than Texaco, BP, Shell etc in general with presumably most if not all of the benefits of their premium fuel.