Now, this may start one of those sit down with a big bag a popcorn sessions.. But, I have a Hilux with a very highly modified diesel. Old school mechanical injection ect. ect.
I normally run United fuel with the occasional tank of BP if nothing else is available. Now, not that I have ever checked it out but I have been told that United buy what ever fuel is the cheapest. Again, not sure if that's true or not..
But, two points.. The truck 'seem' to run better and further on the United. Second point, every two tanks or so, I drop in 2 stroke engine oil, (mineral only) at 300:1 ratio.
When pulling the van I can actually notice the difference in smoothness and pulling. (torque??)..
Also, we do a lot of trips out west where we only use Puma fuels, usually filled up at unmanned road train pumps.
Bottom line is. I have an anaroid system fitted to the injection pump controlled by boost pressure and switched via an electrical solenoid effectively giving me the choice of two fuel maps. Out west using Puma we sit on around 110 -120kph and dont use the higher fuel map unless we are passing a train (or a 200 series towing half a house). But in the occasional times where we have needed to fuel up with BP or Caltex, the anariod is left switched on.. So, I guess it's a case of make of it what you think..