Went for ride on my G/Flash this morning to buy a measuring cylinder and a pipette from a Homebrew shop, total cost was £9.75.
Here's my test results carried out this afternoon. I used 230 ml petrol and 20 ml of water for each petrol type.
After both tests were complete I sucked the water from the bottom of the cylinder up into the pipette, disposed of it and then returned the 95 Unleaded to my lawnmower petrol can and the BP Ultimate to my bike's petrol tank. So there is no waste of fuel doing these tests. Here's a tip for anyone contemplating doing this test: For the first vigorous shake, to mix the petrol and water, I thought I could use the palm of my hand pressed against the end of the cylinder - wrong
petrol up my arm and over the garden path. Then I sealed the end up with a big lump of Blu-Tack. That worked ok and I could give the cylinder a good shake.
At the end of 2017, being concerned about ethanol in my A10, I made a point of checking BP's website and it said BP Ultimate didn't contain ethanol, so I've only been using BP Ultimate since, having not seen anything to the contrary. However, now I see that statement is no longer there. Since this thread was started and looking into it in more depth it seems premium petrol may well be ethanol free (at the moment) but it may depend on where you live. The exceptions, apparently, are Devon & Cornwall (that's me
) and some other areas according to this statement from Esso:-
'Esso super unleaded petrol (Synergy Supreme+ Unleaded 97) is ethanol free (except in Devon, Cornwall, the Teesside area and Scotland). We would therefore advise anyone who has concerns about the presence of ethanol in petrol to use Synergy Supreme+ – providing they do not fill up in Devon or Cornwall, the Teesside area or Scotland'.
It also appears that the ethanol is added to the tanker when filling up at its distribution depot and not at the petrol refinery, so amounts added could be a bit hit and miss.
Maybe the only way to know exactly what you are using is to test the petrol you use, but from what I can gather that can change anytime without you knowing because there is no obligation for petrol stations to tell you.