Supermarket or Super Pricey Fuel, does it make a difference on MPG?

DJ 190

A2OC Donor
I'm starting to think that Tesco diesel is ok but Morrisons isn't.
I would think that the two fuels are identical. That's only my opinion. There will only be brand distinctiveness when you're purchasing a leading fuel.. "Shell", "Esso", "BP", etc. will have a modern, unique additive package.

David
 

PlasticMac

Member
I would think that the two fuels are identical. That's only my opinion. There will only be brand distinctiveness when you're purchasing a leading fuel.. "Shell", "Esso", "BP", etc. will have a modern, unique additive package.

David
David is correct.
Super Markets buy fuel on the open market, although they might have a preferred supplier. That fuel will meet the minimum standards (Ron etc), but, probably, nothing more, as they are buying wholesale, on price. Delivery to the store will be by a contractor, who will collect the fuel from a terminal (often shared by several oil cos). Most, if not all, major oil cos use transport contractors for delivery, not there own fleets, so the delivery vehicle is not a reliable guide to fuel source. Depending on that source (one day it could be good stuff, maybe overstock by a major, who needs the storage space, next day it could be basic spec) you get good, basic, or, more likely, a mix of both. So, the only way to get good stuff everytime is to buy a big brand, from a busy forecourt so you put fresh fuel in your tank. Fuels, (petrol and diesel) deteriorate over time, as the more volatile constituents evaporate, and a typical storage tank at a service station holds 20 - 30,000 ltrs, so can take a while to turn over. You pays your money ... Mac.
 

DJ 190

A2OC Donor
The raw fuel will always originate from the same refinery (unless the location was virtually the same distance from two refinery's) I would have thought that even supermarket fuels would have SOME additive package (although rudimentary). Oh, here's a word of warning (and based on personal experience) If you visit a filling station and observe a delivery tanker filling the tanks or driving away, then give it a miss!. There will be lots of gunge and clag in your fuel if you HAD filled up!

David

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Robthebank

Member
Ok so looks like the last one for a while and got the lowest mpg:
Trip 6 NE- Cornwall, Tesco 68.9mpg, Average | 51mph Average (66.5mph cruising) 1pm start, heavy traffic 14-19deg c, mostly light rain.
I think my higher speed (in a rush) and the rain made the impact, trip 5 on the way up was void as I had a very different route and was also behind schedule so sat on the M6 at 2800rpm **mph, so that’s it for the back to back similar trips for this year, I didn’t get as many in as I thought and for me the data didn’t really show any worthwhile expense in splashing out on premium fuel in terms of an efficiency improvement and if your not get any more efficiency I doubt there’s any extra performance either, so it would be just down to detergents. For me there are two cheaper options for that either flush out with veg oil prior to a filter change or add a specific fuel system cleaner once a year as part of your preventative maintenance, just my thoughts yours welcome also.
 

AndyP

Member
Bearing in mind that the fuel is made to a standard, then there should be little or no difference. Also, for a test to be valid it needs to be blind as your expectations tend to be subconciously applied if you know which fuel you are using. So get someone else to fill up the car and not tell you which fuel was used until afterwards.

Of course, if you have enough datapoints then you can start to infer whether the fuel is a factor. I have tried this over the years, something like 200 fill ups and the most obvious pattern that stands out is the temperature - better fuel economy in the summer.
 
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