I certainly recall when they had a green drum (about 20 gallons?) labelled BP Zoom in between the bowsers. The gas station proprietor poured in the right amount of BP's two-stroke oil and pumped in leaded gas to fill the drum. After that they drew the mixed fuel out from the stopcock at the bottom of the drum when somebody brought in their mower fuel can for filling. I think I even recall one gas station in the latter days of that system that had two of the dispenser-drums with different oil-to-petrol ratios.
