On 22/08/2015 08:22, Adrian wrote:
On Sat, 22 Aug 2015 01:29:30 +0100, John Rumm wrote:

An expert that I trust says that supermarket fuel isn't as good as
other fuel. He says it's all down to the additives.

It also depends on the quantity of ethanol added - particularly on older
engines.

You won't find any petrol that's less than 5% Ethanol, and - unless
clearly labelled E10 - it cannot be more.

I was under the impression that in the UK, the required "biofuel"
content for road transport was achieved by adding 10% FAME (fatty acid
methyl esters, or biodiesel for short) to all diesel fuel, and no
ethanol to petrol. The amount of petrol and diesel used for road
transport is essentially the same, so this gives an average of 5%, which
I think is an EU directive.