Your adds are all over the place, try filling at the same station and using the same fuel adds over a couple of tanks so you can get some idea of whats really happening. I would suggest no more than 1oz. per 10 gal. on the gp7, more than that drops the mpg in my cars.
Yeah Elf I only use about 2-3cc of GP7 not ounces measured with a seringe but the black plunger seal is so dark compaired to the oil that it is hard to read it. I think more of it is the driving conditions that I get and the amount of time it takes to burn a tank - we need dates on the graph!!