A Qantas (I'm assuming he was a tubine tech) guy at my field recently told me that A-1 has an antifreeze in it, and that's the only difference. Other jet fuels have stuff in them that make them different. In Sydney most people use A-1 because there aren't any gas stations that have kero on pump anymore, and because the A-1 will be fresh, whereas if you find a place with kero on pump it could be old and cruddy. To add another question while we're talking fuels, I know most/all turbine guys use a small hopper tank to remove air bubbles. Has anyone toyed with the idea of adding an anti-foaming agent to the fuel? I know the motor racing fuels and oils have it mixed in them - perhaps it may help a bit?