Cooler fuel is more dense , so for same injecton youd be injecting more fuel which will work out at a lower mpg, only seen it done for power.
For the lubricity does you countey have any biodiesel you can add at fuel stations?
Try asking around truck depots im sure hauliers add something.
If no official additives your back to 2 stroke or recently heard of peanut oil added to fuel, you should have no trouble.
I use a 300ml glass sauce bottle and mix myown additive with millers and 2 stroke then tip in tank before i refill.
Turky must have some sort of injector cleaner fluid which usually lubricates as well.
Is there a local internet forum for mpg guys, they will have tested all sorts available to you locally.