The tolerance is to allow for wear. Busy garages (and supermarkets are busy) have their pumps recalibrated as much as twice a day, so the tolerance is always in their favour.

Mind you I once had a chat with a nice Romanian on the Bulgarian border who was on his way back to the Romanian garage to point out that they had sold him rather a lot "more" than his tank would hold. Hope he came out unscathed. Lat time I was in Romania the only place I could buy diesel was the local fire station. Someone making a nice profit there...

Don't forget that just because a garage says it sells a particular make of fuel means nothing. I was once in an Esso station and commented that a Texaco tanker was filling their tanks. The guy said yes it looks like it's Texaco this week, depends on what's cheapest when the boss puts the order in! And do you really think that Tesco has it's own oil refineries or has fuel specially blended?

Incidentally in some rural parts of the country it's difficult to find a non supermarket service station these days. They have all been driven out of business.

its been said on here before, they all fill up with the same diesel/petrol, its the additives that they then place in the tank (at whatever time they do it)

So Tesco has the diesel + its additives to keep i would guess the bare minimum to keep the cost down

but Shell have the same diesel + its own special blend of additives to make its fuel and sell it at what ever cost and sell it as fuel saver diesel

dorsetfreelander wrote:

Incidentally in some rural parts of the country it's difficult to find a non supermarket service station these days. They have all been driven out of business.

Filled up a very empty tank with essos finest after many tanks of morrisons own brand, the tank full has nearly all gone trough the rrs by now and it runs exactly the same. At work
At home

"I can't always believe facts I read on the web" - Charles Dickens

winner by default of the tractor vs caravan race

takes more than one tank, to clean out any residue that might be left behind, also some say its quieter, but i haven't ever noticed a difference

I document my mpg all the time, swapping from tesco were i always went to get my point, to shell when they opened up in the town i live in, increased my mpg by about 3 mpg, with the occasional tank of Nitro+ diesel

Interesting reading here, courtesy of Which:
http://www.which.co.uk/documents/pdf/23-25...186207.pdf

And short Which video about testing methodology here (scroll down page a bit):
http://www.which.co.uk/cars/driving/car-ru...-additives