Diesel

[MichaelE]

The fuel pick up is approx 4" off the bottom so unless the fuel is really contanimated ie as heavier than fuel it sits at the bottom it would take a lot to get picked up

 

[TheCoachman]

I use supermarket fuel all the time on both cars, Rover 75 V6 petrol and 75 diesel both autos and never had any problems.
One thing is I do all my own servicing and change oil and filters including the fuel filter regularly.
I've just had them both on a T4 diagnostic check and on the diesel the guy even commented on the almost level balance on the injector readings, so not gummed up or the like and not bad for a 123k mileage.

The diesel is used for towing our Coachman 520/4 and does it with ease.

 

[chrisbee1]

I usually fill up at either my local Tesco or Morrison purely for convenience. Tesco is invariably 1p more than Morrison but on Monday I noted the following diesel prices in town.
Tesco £1-41.9
Morrison's £1-40.9
Shell & Esso £1-39.9
Texaco £1-38.9

After killing off many of the local filling stations over the years by offering cheap fuel, supermarket fuel, at least where I live, is no cheaper than elsewhere in town. The supermarkets have conditioned us into thinking their fuel will be cheapest and judging by the queues on a Sunday morning at Morrisons their strategy has paid off.

 

[Raywood]

The supermarkets gere are down to £139.9 but the oil companies are 1 or 2p more expensive today but tomorrow who knows. To check local prices try www.petrolprices.com.

 

[ProfJohnL]

I use supermarket fuel all the time on both cars, Rover 75 V6 petrol and 75 diesel both autos and never had any problems..........

Hello Coachman,
I am pleased you have had no issues with supermarket fuel, But if that all you have only ever used, you have not had the oppertunity to compare s/market with traditional branded fuels. This opens the possibility that whilst you may not have had any negative issues with S/market fuels, you might have missed some benefits from branded fuels - However I'm not claiming there are any.

What I find interesting from this and similar threads on other forums is the debate about s/market vs Branded fuels as well as the effects of independant fuel additives.
Obviously each of the companies have a vested interst in claiming thier products are better than the competition. But I have found no conclusive evidence from a wide range of sources that there is any real measurable consistent difference between the mpg performance of any one brand or supplier of fuel.
What is worse is the sale of the additative formulas which make claims of improving mpg or engine performance, Independant testing has shown no statisticaly significant improvements in mpg, and the claimed power gains are often actually small power losses. this is not alltogether suprising, as anything added to fuel that is not as combustable as the raw fuel will reduce the potential energy released from each litre of fuel.
What is more difficult to establish is if any of the claimed cleaning or lubricating benefits of formulations or addiatives are sustainable claims.
This thread demonstrates that most end user reports are highy personal and subjective, and the're based on perceptions rather than scientifically sustainable facts. That not say every one is wrong, its just that you have to treat such reports with a good degree sceptism.

 

[colin-yorkshire1]

hi all,
I may be the odd one out here, but I don't bother were my fuel comes from, or what price it is, having ran out of petrol several times in my youth in some rather isolated places, I never let the fuel gauge go below 1/4 of a tank.
as soon as I need fuel I pull in at the next convienent fuel station and put 30litres in, the price difference is usually less than a £1 anyway.
I cannot say I have noticed any difference in either perfomance or fuel usage between fill ups no matter where the fuel came from, however I have noticed on several occasions, that a supermarket has had huge queues, while the Esso one down the road was empty the price difference 1p,a litre. I cannot for the life of me see the appeal of queueing up for 20mins to save 30p sorry,

 

[otherclive]

Prof John has added to my earlier comments re power and mpg. There are papers published via ASMe and SAE that do show that the additive package in fuels can improve system cleanliness though and to my mind using branded fuels is a better way of putting the detergents and lubricity agents into the system than the periodic dosing with 2T oil or Redex etc.

for what it's worth diesel around me is £1.45.9-£1.47.9 yet 12 miles away its 5-7p less. These are supermarket and independent outlets.

 

[Surfer]

Filled up about 2 hours ago and it was £1.46 per litre in Worcestershire! Supermarkets were selling at £1.40 per litre but we never use supermarket fuels.

 

[VIP640]

I normally fill up my everyday (work) car with Shell but today as I was next to a Morrisons and have recently read so much about adding 2 stroke to a tank of diesel I purchased some Morrisons 2 stroke and added it to a tank of their diesel, I drove home (75 miles) and achieved 55mpg which is slightly better than usual so I will keep an open mind, give it a go and see what results I get.......

 

[otherclive]

Surely though 2t oil is intended to lubricate big ends, little ends in a 2,stroke engine not particularly what would be seen as ideal in a sophisticated CRDI engine where the pump and injectors run at such high pressures and the materials are somewhat different to engine bearings. Seems more like techno- shamanism to me.

 

[woodsieboy]

I have followed this thread for a while and agree with Colin Yorkshire,for work I drive a peugeot diesel van which has now covered 105k,and use whatever fuel is cheapest wherever I happen to find myself,usually Morrisons, or an Esso station in Cheltenham is often cheaper than the supermarkets. For towing I use Shogun and again have not noticed any difference between fuels, although the Shogun always seems to perform more smoothly on a warm day,perhaps it just warms up more quickly.

 

[Gafferbill]

........for me diesel is diesel and the only difference is the additives that are in the fuel.
Some additives are known to help keep fuel injectors working properly so must be beneficial.
What you are prepared to pay comes down to personal choice as any extra mpg if any is very hard to prove.

Don't forget diesels engines also burn air as a fuel so the more air you can get into the cylinders the more power and mpg.
It is known that at or near sea level on a frosty morning a diesel engine will be more powerful than on a warm day at altitude.

So if you live in East Anglia and drive a turbocharged intercooled diesel you should have seen massive savings this March

 

[otherclive]

Surely your fuel pump and injector calibration is aligned with a certain throttle position and demand which meters fuel to the engine. Putting more air (its not a fuel) into the engine will only release more power if there is more fuel, or if the normal fuel air ratio is rich? Most tuning chips or remaps adjust the fuelling of the engine if boost pressure is increased. Just having colder denser air doesn't do it as you also need to allow for increased intake losses too.

Bak to 2t oil I have posted a link to a US tlab tests that looked at lubricity of additives using a bearing scratch test which is one measure of lubrication. 2t oil came 7th out of a wide range of additives but the test results cautioned against using it in post 2007 engines. Bear in mind this was a US paper and the majority of their diesels which are privately owned are commercially derived large capacity engines. Also the scratch test only looked at standard type bearing surfaces and made no attempt to look at the type of modern treatments used in the latest generation engines fuel systems. Other advice on using 2t strongly points to a mineral based 2t not synthetic or semi synthetic. One interesting test on a TD 4 engine using 1:200 of 2t showed regeneration of the DPF changed from every 500-600 miles to 300 miles due to the higher ash content of the 2t. So as ash is what eventually kills a DPF using 2t could half its life.
Given older diesels can run on chip fat and even coal slurry was used on stationary engines years ago I'm not surprised 2t has a loyal following but its a moot point as to wether it should be let loose on a modern engine.
http://www.dieselplace.com/forum/76-gm-trucks/64-maintenance-fluids/177728-lubricity-additive-study-results.html

 

[mcghee]

Normally i respect your opinion gafferbill but in this case i would question your statement. Diesels are extremely tolerant to to mixture ratio which is why most don't have a throttle as we know it. The throttle body is constantly fully open and the torque demand (accelerator pedal position) dictates how much fuel is injected at any given rpm. This is why significant power increases can be had by increasing fuel rail pressure alone (as in the case of most diesel tuning boxes). There is a device on most modern diesels known as the mass airflow sensor which operates as a double check for the ecu. This is cooled by air passing a heated element so it stands to reason that on a cold day the element will cool more and the ecu will assume increased airflow and inject a tiny bit more diesel. The engine can draw in as much air as you like it wont make any extra power unless there's diesel there to burn also.
On the subject of supermarket fuel, many years ago when I used to frequent quarter mile meetings I had a peugeot 309 which ran 14.8 second quarters time and time again using Shell fuel. On the one occasion it was burning Asda's finest it consistently failed to run quicker than 15.2 seconds. This phenomenon was confirmed by a good friend who experienced similar in his tuned RS turbo, so there is a difference, at least in the petrol.
As far as diesel goes, I have three diesels at present. a Renault Trafic 1.9dci, a Vauxhall Corsa 1.7di, and a Freelander td4, and all three (Corsa in particular) sound terrible when cold using supermarket diesel. All three run quietly and smoothly using shell or esso fuel. The Freelander (with Bluespark Automotive plugin remap) is notably torquier with Shell or Esso, and the Renault Trafic differs between 38mpg (supermarket fuel) and 41.5mpg (Shell or Esso). These figures have been checked more than once too.
On the subject of diesel additives, there are a lot on the market which are basically two stroke oil, not good for dpf's, but for some reason seem to make diesels start easier in the cold. As far as I'm led to believe one of the best on the market is Miller's, but good quality diesel shouldn't need it.
As a by-the-way, everyone knows someone who has a story, but a good friend of mine had a Transit TDCi which at less than 40k miles needed recovered due to a failed fuel pump. the ford main dealer lay the blame with Morrisons' diesel, perhaps rightly, perhaps wrongly. Anyhow, I saw the pump which came off and it wasn't pretty.

 

[otherclive]

It's not unknown for engine/fuel system failures under warranty for the garage to take a fuel sample for testing. Presumably if anything that doesnt come from normal fuel is found the warranty may not be honoured. This action seems to stem from failures where petrol has been put into a diesel which moder CRDI engines abhoor, but my old Pajero could probably tolerate to some extent!

 

[Gafferbill]

mcghee…...what you are missing is the
fact that a diesel engine will not completely burn all the fuel that
the injectors deliver .....there is always some fuel wasted.

Modern diesels do, as you point, out
now deliver a much more precise amount of diesel for each compression
stroke of each cylinder. The modern fuel pump and injectors are
controlled by the ECU which in turn gets its information from several
sensors.

Consider the
propane that is contained in a caravan gas cylinder......the volume is
the internal dimensions of the cylinder and the density is so great
it forms a liquid.

Likewise on a cold
frosty morning the air for any given volume is more dense and even
more so at sea level than at altitude.

Since the air is
more dense it contains more Oxygen molecules that are available to
burn more of the otherwise waisted diesel fuel and the engine becomes
more efficient.
Mass Airflow sensors do adjust for this but there is still a efficiency gain on a cold morning/day.

Both the
turbocharger and the intercooler improve the efficiency of a diesel
engine by increasing the density of the air.

The turbocharger
does this by means of an impeller which compresses the air to a
greater density.

The intercooler
does this by means of reducing the air intake temperature immediately
before the air enters the cylinder.

All this matters
because the cylinder has a fixed volume so the only way you can get
more Oxygen into a compression stroke is to increase the density of
the air at the intake of the cylinder.

Previously I described air as
a fuel …....this is technically incorrect of course.

I like to look at
it that way..... I could argue that we do not describe it as a fuel
simply because it is all around us and so plentiful.

A rocket that is
powerful enough to leave our atmosphere has to carry its Oxygen in a
tank just like it does it's so
called fuel.
Is Oxygen a fuel or just an ingredient essential for combustion?

 

[JonnyG]

Surely your fuel pump and injector calibration is aligned with a certain throttle position and demand which meters fuel to the engine. Putting more air (its not a fuel) into the engine will only release more power if there is more fuel, or if the normal fuel air ratio is rich? Most tuning chips or remaps adjust the fuelling of the engine if boost pressure is increased. Just having colder denser air doesn't do it as you also need to allow for increased intake losses too.

Bak to 2t oil I have posted a link to a US tlab tests that looked at lubricity of additives using a bearing scratch test which is one measure of lubrication. 2t oil came 7th out of a wide range of additives but the test results cautioned against using it in post 2007 engines. Bear in mind this was a US paper and the majority of their diesels which are privately owned are commercially derived large capacity engines. Also the scratch test only looked at standard type bearing surfaces and made no attempt to look at the type of modern treatments used in the latest generation engines fuel systems. Other advice on using 2t strongly points to a mineral based 2t not synthetic or semi synthetic. One interesting test on a TD 4 engine using 1:200 of 2t showed regeneration of the DPF changed from every 500-600 miles to 300 miles due to the higher ash content of the 2t. So as ash is what eventually kills a DPF using 2t could half its life.
Given older diesels can run on chip fat and even coal slurry was used on stationary engines years ago I'm not surprised 2t has a loyal following but its a moot point as to wether it should be let loose on a modern engine.
http://www.dieselplace.com/forum/76-gm-trucks/64-maintenance-fluids/177728-lubricity-additive-study-results.html

Air temp and by that it also means density too, does indeed play a part in how much power you have available, although its nothing on a grande scale but as you can loose 10% power at 1000 metres above sea level this clearly shows how Air density plays an important part.manufacturers quote bhp and torque figurers off the test bench done at ,13 degrees C ambiante temp so to keep all things level.Most diesels these days have an intercooler fitted although that wasnt always the case,the higher spec car would have one and the low spec car would not. Ie vauxhall vectra circa 97.. 2.0L non intercooler 82bhp. intercooler version 100bhp. of course
the intercoolers job is to cool down the Ambiate Air temp,if it wasnt of importance [air temp/density] you wouldnt need one.
My mondeo has an after market larger one fitted.
As for 2 stroke oil, Low ASH 2 stroke oil is what one should be using dont know what the yanks used, as low ash 2 stroke oil contains less Ash than diesel fuel itself then why their cars regenerated earlier i have no idea as 1 part of 2 stroke oil to 200 parts diesel should not make any difference what so ever....
I still use low ash 2 stroke oil on ocassions but mainly use millers additves as its also a cetane raiser which i believe 2 stroke oil is also. and no i dont notice any difference but then its alll for my own piece of mind..

 

[Whitaker1953]

I have just had a new EGR valve fitted to an 09' VW Sharan at a cost of £450. This is the second time the car has broken down through EGR being bunged up since bought as new. I always use Supermarket diesel and never buy upper grade fuel from forecourts. Is there a lesson to be learned here?

 

[Dustydog]

IMO .Yes,.

My last car we had from new. At 60k it was belching black smoke. A new EGR valve and turbo pipes solved the problem.
Main dealer blamed the fact I had only used supermarket own brand diesel.
We sold the car at 126k in perfect smoke free condition having used two blue chip fuel tankfulls to one supermarket.
The subject has been to death over the years on here. A very wide difference of opinion.

I believe my and your experience prove the point supermarket diesel is inferior.

 

[ProfJohnL]

I have just had a new EGR valve fitted to an 09' VW Sharan at a cost of £450. This is the second time the car has broken down through EGR being bunged up since bought as new. I always use Supermarket diesel and never buy upper grade fuel from forecourts. Is there a lesson to be learned here?

I cant answer your rhetorical question, but I can pose another one, Each of drives differently, so the issues you have had could have been caused by driving styles and habits, just as much as the presence or otherwise of fuel additives.

 

[otherclive]

Surely your fuel pump and injector calibration is aligned with a certain throttle position and demand which meters fuel to the engine. Putting more air (its not a fuel) into the engine will only release more power if there is more fuel, or if the normal fuel air ratio is rich? Most tuning chips or remaps adjust the fuelling of the engine if boost pressure is increased. Just having colder denser air doesn't do it as you also need to allow for increased intake losses too.

Bak to 2t oil I have posted a link to a US tlab tests that looked at lubricity of additives using a bearing scratch test which is one measure of lubrication. 2t oil came 7th out of a wide range of additives but the test results cautioned against using it in post 2007 engines. Bear in mind this was a US paper and the majority of their diesels which are privately owned are commercially derived large capacity engines. Also the scratch test only looked at standard type bearing surfaces and made no attempt to look at the type of modern treatments used in the latest generation engines fuel systems. Other advice on using 2t strongly points to a mineral based 2t not synthetic or semi synthetic. One interesting test on a TD 4 engine using 1:200 of 2t showed regeneration of the DPF changed from every 500-600 miles to 300 miles due to the higher ash content of the 2t. So as ash is what eventually kills a DPF using 2t could half its life.
Given older diesels can run on chip fat and even coal slurry was used on stationary engines years ago I'm not surprised 2t has a loyal following but its a moot point as to wether it should be let loose on a modern engine.
http://www.dieselplace.com/forum/76-gm-trucks/64-maintenance-fluids/177728-lubricity-additive-study-results.html

Air temp and by that it also means density too, does indeed play a part in how much power you have available, although its nothing on a grande scale but as you can loose 10% power at 1000 metres above sea level this clearly shows how Air density plays an important part.manufacturers quote bhp and torque figurers off the test bench done at ,13 degrees C ambiante temp so to keep all things level.Most diesels these days have an intercooler fitted although that wasnt always the case,the higher spec car would have one and the low spec car would not. Ie vauxhall vectra circa 97.. 2.0L non intercooler 82bhp. intercooler version 100bhp. of course
the intercoolers job is to cool down the Ambiate Air temp,if it wasnt of importance [air temp/density] you wouldnt need one.
My mondeo has an after market larger one fitted.
As for 2 stroke oil, Low ASH 2 stroke oil is what one should be using dont know what the yanks used, as low ash 2 stroke oil contains less Ash than diesel fuel itself then why their cars regenerated earlier i have no idea as 1 part of 2 stroke oil to 200 parts diesel should not make any difference what so ever....
I still use low ash 2 stroke oil on ocassions but mainly use millers additves as its also a cetane raiser which i believe 2 stroke oil is also. and no i dont notice any difference but then its alll for my own piece of mind..[/quote

Johhny the TD4 engine is a UK engine fitted to Freelander 1 and 2. The tests using 2T oil and regeneration frequency were British ones not American. Under their controlled conditions variables such as driver style, traffic congestion, weather etc were reduced so the tests compared regeneration periodicity under controlled conditions using a set cycle and the same fuel throughout. Many don't realise that when a DPF regenerates it burns the carbon soot particles but these will generate an ash residue which eventually leads to clogging of the DPF. Comparing the spec for branded and premium branded diesel the latter have much lower ash content. So I guess you pays your money and takes your choice. Hence when we sold the van the diesel XC70 went too, and its successor was petrol, without turbo/DPF/DMF/intercoler and CRDI system. Oh what joy, and i note that the CC is also following my lead by now allowing tents on quite a number of sites!

 

[teal1928]

This is a old chestnut problem, many people who have watched the tankers at their depot say it all comes for the same place. Putting that aside lets be factual. I use Morrisons because I get £5 off my shopping. Next, I get an average over 9 years 43 mpg this includes towing and solo and at moment it reads 55600 miles.I also get up to 70 mpg on some runs going by the OBC !!. Summing up how many mpg would I get by going to ESSO /SHELL/ BP?

 

[teal1928]

You have got it at one, its how we drive, boy racers don't have that problem we should have a"burn" up every so often if we just potter around. I suppose when we tow it gets a bit of "welly". My EGR also cost a fortune plus the turbo went as well, total cost over a £1000, so put your foot down chaps.

 

[Dustydog]

Sorry not so simple.

We did the 60k in three years.
Mostly 200 plus journeys nonstop. Very little low mileages.

 

[seth1]

I wonder how anybody including myself can make a solid prognosis on an egr valve failing and the cause.Was it the electric part of the valve or the mechanical part?Does the vehicle have issues else were.i know for a fact vag 2 litre diesels have injector problems and oil consumption issues.Ive never replaced an egr valve on any of my vehicles,all ran on super markert fuel,all of inferia Italian construction,present one is now 6 years old.