Checked today and yep the E5 pump is the one I now avoid for car. Bike, I can use both E5 and E10 with no issues though the E5 does appear more mpg (96mpg)Sounds strange, I thought E10 was the new formula, and some older equipment might need to stick with E5.
E5 higher octane with this blurb from esso-
What’s in our Synergy Supreme+ 99 premium petrol?
Our Synergy Supreme+ 99 petrol has more cleaning power than our regular petrol – and includes molecules engineered to reduce friction in your engine and help moving parts work more efficiently.**
We currently supply an ethanol-free Synergy Supreme+ 99 unleaded in some parts of the UK. From September 2023 our Synergy Supreme+ 99 will transition to contain up to a maximum of 5% ethanol at all Esso pumps irrespective of which part of the country they are located. The labelling at our pumps will remain as E5 for Synergy Supreme+ 99 unleaded.
Have you tried the E10 in the machine? might be worth a go.