I was reliably told by the fuels chemists (I specialised in lubricants) that the dosing is done at the gantry. The truck driver has a card or something similar that is specific to the brand which is inserted at the gantry. The base fuel all comes out of the same tank and then depending upon the card inserted the proprietary additives are pumped from another tank and mixed at the gantry. I guess the mixing ratio etc is all managed by the dosing mechanism at the gantry. They can carry multiple brands/grades in each of the trucks but a different “brand specific card” will be inserted for each tank on the truck which is why people may see the same truck delivering to different fuel stations but with different mixtures/brands in each tank.Thanks Perusal.
For my professional curiosity with a Supply Chain hat on.
Do you know where the branded additives are added to the tanker loads as the load manifests I've seen just shows the fuel loaded as so many thousand litres in each of the compartments? If there were additional branded additives then there would have to be some sort of mix ratio for the volume of fuel per compartment I guess?