No haven't tried Gull
Have tried
Shell
BP
Caltex
All with and without Cetane booster
Caltex lets engine rev to redline quicker but makes engine very clattery on tickover???
I find that very interesting, being that Shell, BP, Mobil and Caltex diesel is exactly the same... no additives specific to each brand, just plain old Marsden Point diesel. I know this as I did my time unloading tankers on the wharf in Tauranga... all the brands tank farms are within a 1.5km radius and are fed from the same pipe.
We just open the valves to the appropriate tank farm for the pre-determined time (based on viscosity/flow-rate of the product.. petrol or diesel)
Gull is the only company to source its products from offshore, usually ex-Singapore.