Mogas -2.5% alcohol in all forecourt petrol from April.

[Mariner9]

For Backpacker and everyone:

The official procedure is to use ASTM method D1094 or the equivalent IP289. In this method, 80 ml of fuel sample is shaken with 20ml of water (Well actually, its a "phosphate buffer solution" which is water with K2HPO4 and KH2PO4 but pure (distilled ideally) water will do for a field test) in a graduated glass cylinder for 2 minutes at a rate of 2-3 strokes per second.

The water volume is measured before and after the test to the nearest 0.5ml. The maximum increase to meet Avgas specs is a 2ml increase, which, if all water miscible components seperated into the water phase, would equate to 2.5%.

Therefore, even if a Mogas contained 2.5% ethanol, and that all ethanol seperated into the water phase (which it wont), then the fuel would still be within the limits specified for Avgas and hence suitable for use as an aviation fuel.