Just for the record, I would not advise putting any oil or lubricant anywhere near your REALLY HIGH PRESSURE air system. Although its likely to be fine, it is not worth the risk. Cleaning the threads with an old toothbrush will do the same job.Thoroughly clean the threads on both bottle & asa. Lubricate both threads lightly with marker lube (silicon-based stuff).
Ensure the o-ring on the bottle thread is in good condition.
Use a thread protector (<£5) on the bottle when not in use.
Have had same probs with several minis; after doing the above, able to unscrew the bottle with ease when gassed up.
Its not you im worried about. They see you doing something safe, pop home, and wd40 their fill nipples. Personally, if you want to do it, fine, but be careful how you word it publicly.Hydrocarbon-based lubricants, you're right, Bolter.
Silicon-based lube has a low chemical-reactivity, amongst other properties, hence its use in high-pressure systems. eg diving equipment.