I think I agree with you regarding messing around with petrol but it does look so easy to do, I’m thinking small amounts more for my mower so I don’t have to worry about draining it all the time and because Additives are expensive !. Curious to know if the petrol is 100% water free after it separates with the ethanol though ??
You mix food colouring with a measured amount of water and as it absorbs the ethanol the percentage of coloured liquid increases. skim off the coloured liquid and you remove the water and ethanol mixture.