Is supermarket diesel really cheaper?l

Having heard rumours about the quality of supermarket diesel I conducted some tests with my 1997 Discovery 300 Tdi by driving around 1000 miles on each of Shell V-Power , Shell and Esso bog-standard diesel and supermarket stuff from Sainsbury and Tesco. Results were as follows:-

V-Power cost 22.87p per mile (£22.87 per 100 miles)
Shell and Esso cost 22p per mile and
Supermarket cost 21.5p per mile.
If you have a 20p per litre discount voucher for Tesco, that brings the cost down to between 18 and 19p per mile.

Not much in it, really, but it is very noticeable, even in this 132000 mile engine, that she runs a lot smoother on "real" diesel than on supermarket stuff. Couldn't detect any difference with the V-Power but I suppose that's no surprise in a relatively low-tech engine.

I have also used recycled cooking oil which is very cheap at 50p per litre but performance is reduced, starting is not so good, it will wax up in cold weather and you need to keep a close eye on the filter of the lift pump and also the fuel filter if you don't want to come to a sudden stop when it blocks up with the clag cleaned out by the veggie oil. Mixing it with diesel helps but then it doesn't save enough to be worth the bother.

I also tried heating oil (Kerosene or Paraffin) with 5% vegetable oil added. This was proper rapeseed oil in a bottle from the supermarket, not the thick old recycled stuff. The rapeseed oil lubricates the pump and gets the specific gravity to more or less what the engine was designed for. The old girl ran fine and fuel costs were at least halved. That was, of course, done purely and strictly in the interest of science and I neither recommend the practice nor do it myself now the experiment is over.

Old Seadog said:

Having heard rumours about the quality of supermarket diesel I conducted some tests with my 1997 Discovery 300 Tdi by driving around 1000 miles on each of Shell V-Power , Shell and Esso bog-standard diesel and supermarket stuff from Sainsbury and Tesco. Results were as follows:-

V-Power cost 22.87p per mile (£22.87 per 100 miles)
Shell and Esso cost 22p per mile and
Supermarket cost 21.5p per mile.
If you have a 20p per litre discount voucher for Tesco, that brings the cost down to between 18 and 19p per mile.

Not much in it, really, but it is very noticeable, even in this 132000 mile engine, that she runs a lot smoother on "real" diesel than on supermarket stuff. Couldn't detect any difference with the V-Power but I suppose that's no surprise in a relatively low-tech engine.

I have also used recycled cooking oil which is very cheap at 50p per litre but performance is reduced, starting is not so good, it will wax up in cold weather and you need to keep a close eye on the filter of the lift pump and also the fuel filter if you don't want to come to a sudden stop when it blocks up with the clag cleaned out by the veggie oil. Mixing it with diesel helps but then it doesn't save enough to be worth the bother.

I also tried heating oil (Kerosene or Paraffin) with 5% vegetable oil added. This was proper rapeseed oil in a bottle from the supermarket, not the thick old recycled stuff. The rapeseed oil lubricates the pump and gets the specific gravity to more or less what the engine was designed for. The old girl ran fine and fuel costs were at least halved. That was, of course, done purely and strictly in the interest of science and I neither recommend the practice nor do it myself now the experiment is over.

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I thought SVO is not any good for lubrication. I could be wrong here of course (I am often am!)

Heating oil is different from kerosene and from paraffin. All 3 are different fuels (though it depends whats on the pump as to what someones definition of "heating oil" is I believe?

The "heating oil" at our local pump is just red diesel.

35sec is red deisel, 28 sec is home heating usually.

no idea on penceper mile

but i work on the fact that my engines(1.9 DW8s atm) SOund happier on real diesel - its mostly tesco diesel(doesnt matter what branch i use) that makes it run crap ill be honest. morrisons/asda/sainsburys all run fine - like wise shell and BP

on top of that i found i get between 525-550 consistantly on non tesco diesel and on tesco diesel between 425 and 450 consistantly. doing similar trips &i always fill to brim and zero milage

french supermarkets are even worse on economy.

then theres the fact that tesco fuel has up to 6% biodiesel in and some manufacturers only warrrenty for use to E5 - 5% biofuel in petrodiesel. - older direct injection engines suffer worse in this respect.

BBC News - Biofuel suspected in probe into diesel breakdowns

also.

28 sec kerosene is home oil - its really "dry" has no lubricity. If you ever get it on your hands you can feel difference.

(oil central heating here - the scraps from my tank when it was drained were cycled through my 19j but in high dilution with regular derv)

Old Seadog said:

Having heard rumours about the quality of supermarket diesel I conducted some tests with my 1997 Discovery 300 Tdi by driving around 1000 miles on each of Shell V-Power , Shell and Esso bog-standard diesel and supermarket stuff from Sainsbury and Tesco. Results were as follows:-

V-Power cost 22.87p per mile (£22.87 per 100 miles)
Shell and Esso cost 22p per mile and
Supermarket cost 21.5p per mile.
If you have a 20p per litre discount voucher for Tesco, that brings the cost down to between 18 and 19p per mile.

Not much in it, really, but it is very noticeable, even in this 132000 mile engine, that she runs a lot smoother on "real" diesel than on supermarket stuff. Couldn't detect any difference with the V-Power but I suppose that's no surprise in a relatively low-tech engine.

I have also used recycled cooking oil which is very cheap at 50p per litre but performance is reduced, starting is not so good, it will wax up in cold weather and you need to keep a close eye on the filter of the lift pump and also the fuel filter if you don't want to come to a sudden stop when it blocks up with the clag cleaned out by the veggie oil. Mixing it with diesel helps but then it doesn't save enough to be worth the bother.

I also tried heating oil (Kerosene or Paraffin) with 5% vegetable oil added. This was proper rapeseed oil in a bottle from the supermarket, not the thick old recycled stuff. The rapeseed oil lubricates the pump and gets the specific gravity to more or less what the engine was designed for. The old girl ran fine and fuel costs were at least halved. That was, of course, done purely and strictly in the interest of science and I neither recommend the practice nor do it myself now the experiment is over.

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No idea what happens where you are, but in Cornwall there is only one oil terminal, it is in Falmouth docks. So all the fuel comes out of the same tanks. No difference in supermarket fuel at all.

Veg oil is ok in a mix, but it is very cleaning inside the fuel system, so well worth checking filters etc. regularly when you start using it. I would add a lubricity additive to protect the pump from wear if I was using veg oil.

As vilguy suggests, some boilers actually run on red diesel anyway! Others run on kerosene, and this is not good to run vehicles on. Sooner or later it will knacker your injector pump.

"So all the fuel comes out of the same tanks."

i agree - but then the additive packs are added afterwards depending on which client its going to - this includes the biodiesel.

there are also different methods of adding the biodiesel

top drive said:

then theres the fact that tesco fuel has up to 6% biodiesel in and some manufacturers only warrrenty for use to E5 - 5% biofuel in petrodiesel. - ol

also.

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According to the firm that supply our red diesel on the farm, all diesel, red and white, now sold in EU contains a percentage of biofuel.

They wrote to us several times about it as many people had problems with their tractors when it was first introduced. Seems like they have got the formulation a bit more stable now, and the customers have cleaned up their storage facilities. We don't hear so much about issues with it now

yes agree - but it doesnt all contain the same level of bio.

tesco has one of the highest in uk - as i stated before no all current cars are compatible with more than 5% and bio affects older cars more than newer.

top drive said:

yes agree - but it doesnt all contain the same level of bio.

tesco has one of the highest in uk - as i stated before no all current cars are compatible with more than 5% and bio affects older cars more than newer.

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That is what I have heard too Variable percentage, could be as random as what they had to use up in the refinery tanks.

For these reasons I have never taken any chances with my old vehicles, I bought a quality additive in bulk. When we fill the red tank I premix, and when I fuel the landy I add the additive at the fuel station.

I hate Tesco, so I don't go there, usually use shell, that is our local fuel station, but I have used Sainsbury and Morrisons without ill effects.

I sometimes think people would do well to pay a bit more attention to the actual service station as well as the fuel. Old rusty tanks, with water in them, and the fuel sitting in them for ages cos they don't sell much, could also cause problems I would guess!

aye i wont use tesco unless im really in a bind.

notice the difference pretty quick as the dw8 engine starts to hunt - its a pretty resilliant engine but tesco fuel seems to really screw it up. My dads puma engined transit just point blank refused to idle on it. yet as soon as he runs it on shell it idles fine....

also - biodiesel has different Specific gravity so surely it will separate inthe tanks once its sat for a while....if thetanks are low (given that tesco run out of diesel quite often) surelythere isa chance you will get a tankfull of high concentrate bio - or do tanks have agitators in like my mud pits off shore?

In my '96 300TDi Disco I run a twin tank setup for cleaned waste veg oil, and mix in around 5% 2 stroke oil. Without the 2 stroke the engine revs will max out at about 3300 rpm, whearas on supermarket derv it will rev as high as I dare to.. which isn't very high

Millers cetane improver helped both derv and WVO run better, but the difference is felt even better with mineral 2 stroke oil.

If I mix in 5% or so 2 stroke oil into my main derv tank it also improves the diesel running - quieter, smoother and picks up better.
It's many years since diesel had the level of lubricants our Tdi's were designed to run with, so I think a little TSO in the tank can really help protect the injection pump.

its just I`m a creature of habit..
I buy my clean fresh new veggie or sunflour oil in tescos

stick it in the tank outside tescos front doors, then drive round to it service station and top up with pumped diesel....
by the time I`m home, about 6 miles, its more or less mixed by then.

my old disco just keeps going no matter what I put in the tank TBH....
I`ve miss filled with £20 of unleaded, after 10 litres of sunflour oil,
poured £20 of derv over the top, then drove back to the store for another 10 litres of sunflour oil on top of all that.
I did conceid to adding a dollop of 2T to it all, but it just ran as normal..

I was running a bit low on veggie/derv mix today so stuck £15 of morrisons derv in, and on the way home, my old disco did have more grunt than normal, but clatters a bit more...
never bothered with miles per gallon,
I`m only bothered about running low on fuel,
but compaired with my petrol lexus, the old disco driven sensibly does do more per gallon I expect.....

I`m happy anyway..

Squirt in some 2 stroke everytime - the veg oil isn't good at all at lubricating the high pressure injection pump or injectors. It's bliddy good at cleaning the system out though, as has been said!

You is a braver man than I for starting it on the veg oil mix - I almost always start on derv to save coking and ring gumming. Fingers crossed it's ok, and the sump oil is veg free so far which makes me one happy cheap skate!

top drive said:

also - biodiesel has different Specific gravity so surely it will separate inthe tanks once its sat for a while....if thetanks are low (given that tesco run out of diesel quite often) surelythere isa chance you will get a tankfull of high concentrate bio - or do tanks have agitators in like my mud pits off shore?

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Biodiesel is miscible in derv in any proportion and once mixed will not seperate.
As biodiesel has a higher cetane number than derv,it is probably other junk they are adding to supermarket fuel which is causing performance issues, and the bio is attempting to bring it right.
I run my TD5 on 100% bio and seems fine,certainly much much quieter and loads of grunt

biolandy said:

Biodiesel is miscible in derv in any proportion and once mixed will not seperate.
As biodiesel has a higher cetane number than derv,it is probably other junk they are adding to supermarket fuel which is causing performance issues, and the bio is attempting to bring it right.
I run my TD5 on 100% bio and seems fine,certainly much much quieter and loads of grunt

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More likly the stuff the DONT add...

TBH, id be surprised if most of it isnt placebo effect on what it runs like, especially on the TDIs, which are designed to be run an poor quality fuel found abroad.
Fuel is made to an EN standard, the "brands" put in various addatives to make it "better"
If it contains bio, there will be a "B" numbe ron the pump, ie B5, B10 for 5% or 10% respectivly up to B100 for 100 Biodeisel

Mine runs the best (and cleanest )on B100, and it shall stay that way

The price of diesel varies tremendously round here, the local tescos ( 5 miles away) is 5p+ more than the next tescos 20 miles Away. However mostly I now fill up at ESSO which gives me tesco points, and is about as cheap as I can get between home and work.

Each 45 litres of diesel gets 200ml of TSO as does veggie oil.

the current years records show that I've varied between 10% veggie in the spring up to 65% in high summer I'm now on the way down again intending to be below 10% by the first frost.

I have difficulty in getting cheap veggie oil round here the best I've found is tesco 10 litres for £8. So when the distant tescos has any I always buy it. The local branch doesn't stock it.

The trouble is not so much the additives, but the sulphur they're removing - the more there is, the better the lubricity of the fuel. As its seen as a big nasty part of mineral diesel they try and cut down the amount in it to give cleaner emissions and appease the bunny huggers, but older vehicles depend on the sulphur for lubrication.

Enter mineral 2 stroke oil is small quantities and the balance is restored...

Saltlick said:

Enter mineral 2 stroke oil is small quantities and the balance is restored...

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I wouldn't! Two stroke oil is not formulated for this, and will have little benefit. It may make your engine smoky and encourage bacterial growth.

It is much better to use a proper lubricity additive, there are many on the market, and bought in bulk it will be cheaper than two stroke oil anyway.