Posh Diesel

[barge sara]

Lots of fuel stations sell two grades of diesel fuel. The ordinary fuel, currently around 112p / litre, and the 'posh version', usually about 5p dearer.

What does it do? Is it worth the extra, i.e does it deliver a corresponding or better saving in fuel consumption or other running cost?

Or is it, as I suspect, a marketting scam designed to relieve us of a little extra cash?

 

If it is worth the extra in road vehicles, is there any advantage in boats?

[Albion]

Lots of fuel stations sell two grades of diesel fuel. The ordinary fuel, currently around 112p / litre, and the 'posh version', usually about 5p dearer.

What does it do? Is it worth the extra, i.e does it deliver a corresponding or better saving in fuel consumption or other running cost?

Or is it, as I suspect, a marketting scam designed to relieve us of a little extra cash?

 

If it is worth the extra in road vehicles, is there any advantage in boats?

 

Evidence seems to be difficult to obtain and somewhat variable IMO. Honest John in the Telegraph seems to reckon that it is worth it for the additional detergent content to keep injectors clean etc and claims improved MPG. I've recently run a crude experiment on my Mk2 Freelander and could detect no difference between the two types. Perhaps the main benefits might only show after very high mileage.

It would be a waste of money to use this quality of fuel in pleasure craft diesels IMO as they are mainly based on industrial diesels designed and developed for rough treatment and lack of care/neglect in the field. They don't also tend to have the highly sophisticated type of injection equipment (yet) that road vehicles do.

Roger

 

Edited to add:

I am, however, not convinced that the 'red' that is sold in the UK for narrow boats is the same basic quality as the standard DERV used in vehicles. I base this opinion on the coking up that occurs on Mikuni/Webasto/Eberspacher diesel heaters for example. I had a Mk1 Freelander that used a (Webasto, I think) pre-heater unit to assist engine warm-up when the ambient air temperature fell below certain parameters. This unit used to kick in and run OK without any attention whatsoever, indeed there were no servicing requirements specified in the service schedule at all that I could find. If you treated a boat unit of the same design in the same way it would soon coke up and stop. However, I also had a Mikuni on a boat in France (where you have to use white (DERV) for leisure boating) and it ran perfectly without any problems of coking.

So, I'm dubious about the 'so-called' red being of comparable quality to DERV.

Before anyone reminds me that you can use red for heating and electricity generation in France, yes I know that, but the tank arrangement on my French boat didn't lend itself to storing two types so I just burnt white for heating and propulsion. It is also not easy to buy small quantities of red in France unless you can piggy-back onto a large tanker delivery that is being made to a nearby hotel craft for example.

Edited January 25, 2010 by Albion

[nb Innisfree]

Our Mukuni has suffered smoking since we fitted it 4+ years ago despite trying everything, but for the last few months it's behaved perfectly and I put it down to the decreasing production of gas oil leaving us with what is in effect road diesel with pink dye added as gas oil originally was many moons ago.

[smileypete]

Our Mukuni has suffered smoking since we fitted it 4+ years ago despite trying everything, but for the last few months it's behaved perfectly and I put it down to the decreasing production of gas oil leaving us with what is in effect road diesel with pink dye added as gas oil originally was many moons ago.

Interesting, did you try a cetane booster or water dispersant?

 

cheers,

Pete.

[bag 'o' bones]

I think there is a diffrence in purity between red diesel and normal road diesel but I don't think the 'performance road diesel has enough benefits to justify the extra 5 pence per litre.

 

Thing is preformance road diesel is designed for high performance car engine not a slow revving boat engine.

 

As for the so called detergent properties I think you might as well use wynns injector cleaner or similar and whop that in the tank occasionally.

[alan_fincher]

Edited to add:

I am, however, not convinced that the 'red' that is sold in the UK for narrow boats is the same basic quality as the standard DERV used in vehicles.

 

............................................

 

So, I'm dubious about the 'so-called' red being of comparable quality to DERV.

 

I don't think many people currently make that claim - it has been much discussed on here in many previous threads.

 

Most "red" currently sold at canal-side outlets will be dyed gas-oil, not dyed "DERV", (the road fuel).

 

From memory DERV has to have a sulphur content of no more than 50 parts per million, whereas gas oil is still (I think) permitted to cotain sulphur at up to 2000 parts per million.

 

If those numbers are right (?) and realised in practice, then canalside "red" could contain 40 times more sulphur than diesel bought as roadsde DERV.

 

That's one big difference, although it seems to make little difference to typical narrow boat engines - rather more to diesel heating systems based on lorry cab heaters!

 

(Note it is possible to buy "ultra low sulphur" "red" - i.e. effectively road DERV, with dye in, but it's very much more likely that what a canalside retailer is selling is the higher sulphur stuff, I think.)

[nb Innisfree]

Interesting, did you try a cetane booster or water dispersant?

 

cheers,

Pete.

 

Yes we have always used Fortron and still do, the smoking seemed to be even worse when we used Morrison's fuel additive for a while but still reverted to the usual smoking when we went back to Fortron. I stand correcting but I believe gas oil has now been banned by the EU and any existing gas oil is in the pipeline so to speak? Gas oil is yesteryears road diesel and modern road diesel is more siutable for today's DERVs

[Proper Job]

Most NB engines are derated cousins of their industrial variants.

 

Combine that with our love of not working them hard (we spend most of our time cruising at less than half of max revs) and fitting overpowered engines in the first place, I doubt that most engines are never worked hard enough for it to make a difference.

 

Car diesels are max'ed out at a much higher rpm (> 4,000). The diesel 'burn' becomes inefficient at these speeds so an 'enhancer' could potentially make a difference

[alan_fincher]

I stand correcting but I believe gas oil has now been banned by the EU and any existing gas oil is in the pipeline so to speak?

I've not heard that.

 

It is still easily possible, via Google, to find specification sheets for UK suppliers of Gas Oil where the quoted maximum sulphur content is as high as 2000 parts per million, (also quoted as 0.2% by weight).

 

Some suppliers say less, and an Esso data sheet shows a maximum of 1000 parts per million, but quotes the typical amount in supplied gas oil at 850 parts per million. That is still 17 times more than the maximum I think is permitted in DERV used in road vehicles.

[Roger Gunkel]

From memory DERV has to have a sulphur content of no more than 50 parts per million, whereas gas oil is still (I think) permitted to cotain sulphur at up to 2000 parts per million.

 

If those numbers are right (?) and realised in practice, then canalside "red" could contain 40 times more sulphur than diesel bought as roadsde DERV.

 

Thats about right Alan, from the reasearch I did and conversations with several oil companies during my long running Eberspacher saga.

 

The claim by the heater manufacturers was that dirty fuel was causing all the problems, whereas it was actually the much higher sulphur levels in Red contributing to the build up of residues and carbon. The general response from different oil companies was that red diesel had stayed at virtually the same spec for the last 25 years or so, whilst road diesel had been changed considerably in that time, with minimalised sulphur levels and various other additives to help lubrication, cleaning etc as the demands of modern road engines increased.

 

(Edited to say) There are sulphur reduced red diesels available now, but rarely found on the waterways.

 

Roger

Edited January 25, 2010 by Roger Gunkel

[Albion]

I don't think many people currently make that claim - it has been much discussed on here in many previous threads.

 

Most "red" currently sold at canal-side outlets will be dyed gas-oil, not dyed "DERV", (the road fuel).

 

From memory DERV has to have a sulphur content of no more than 50 parts per million, whereas gas oil is still (I think) permitted to cotain sulphur at up to 2000 parts per million.

 

If those numbers are right (?) and realised in practice, then canalside "red" could contain 40 times more sulphur than diesel bought as roadsde DERV.

 

That's one big difference, although it seems to make little difference to typical narrow boat engines - rather more to diesel heating systems based on lorry cab heaters!

 

(Note it is possible to buy "ultra low sulphur" "red" - i.e. effectively road DERV, with dye in, but it's very much more likely that what a canalside retailer is selling is the higher sulphur stuff, I think.)

 

As the sulphur is used to assist lubrication of injection equipment it is probably just as well that it still exists to a greater extent than for road vehicles because of the older-style injection equipment used on boat engines and, particularly, for vintage engines. It has been drastically reduced in vehicles to cut down the oxides of Sulphur that were causing problems for city dwellers especially..........hence the term City Diesel that some fuel suppliers used.

Roger

Edited January 25, 2010 by Albion

[nb Innisfree]

I've not heard that.

 

It is still easily possible, via Google, to find specification sheets for UK suppliers of Gas Oil where the quoted maximum sulphur content is as high as 2000 parts per million, (also quoted as 0.2% by weight).

 

Some suppliers say less, and an Esso data sheet shows a maximum of 1000 parts per million, but quotes the typical amount in supplied gas oil at 850 parts per million. That is still 17 times more than the maximum I think is permitted in DERV used in road vehicles.

 

It's been discussed in previous threads, western distillers are supposed to have suspended production of gasoil as it is becoming uneconomical to produce both due to legislation, eastern ones , China in particular haven't but may be forced to so as to keep supplying Europe.

 

I stand being corrected on all this btw.

[smileypete]

Yes we have always used Fortron and still do, the smoking seemed to be even worse when we used Morrison's fuel additive for a while but still reverted to the usual smoking when we went back to Fortron. I stand correcting but I believe gas oil has now been banned by the EU and any existing gas oil is in the pipeline so to speak? Gas oil is yesteryears road diesel and modern road diesel is more siutable for today's DERVs

Thanks, any more details on this additive? Do you mean Morrison's the supermarket or Morris Lubricants maybe?

 

cheers,

Pete.

[GUMPY]

To go back to the original question.

The high performance diesel will only give you additional fuel savings if your car or boat has an ECU that will adjust the fuelling on the fly.

My BIL has a BMW and he does see a noticeable difference in MPG between normal diesel and the high performance, stuff when I had my diesel polo there was no noticeable difference.

The same applies to super unleaded unless your car has an ECU that will take advantage of it or you have a high performance engine there is very little to be gained by using it.

One final point "City Diesel" contained at last 5% bio diesel as that was the only way that they could get the emissions down far enough to meet the standards. Now almost all diesel sold on forecourts contains between 5 and 10% bio.

When it becomes law in 2011 that we can no longer use gas oil but have to use low sulphur I expect to see an increase in diesel bug due to the 5-10% bio and the fact that diesel on the cut sits in tanks for ages.

[Proper Job]

I wound up ye olde JP to the full 1000 rpm going up a fast running Cherwell at the weekend.

 

Judging by the amount of soot that was blowing out of the exhaust and raining down, I don't think the ECU was compensating that well

[nb Innisfree]

Thanks, any more details on this additive? Do you mean Morrison's the supermarket or Morris Lubricants maybe?

 

cheers,

Pete.

 

Sorry, I meant Morris Lubricants.

 

 

To go back to the original question.

The high performance diesel will only give you additional fuel savings if your car or boat has an ECU that will adjust the fuelling on the fly.

My BIL has a BMW and he does see a noticeable difference in MPG between normal diesel and the high performance, stuff when I had my diesel polo there was no noticeable difference.

The same applies to super unleaded unless your car has an ECU that will take advantage of it or you have a high performance engine there is very little to be gained by using it.

One final point "City Diesel" contained at last 5% bio diesel as that was the only way that they could get the emissions down far enough to meet the standards. Now almost all diesel sold on forecourts contains between 5 and 10% bio.

When it becomes law in 2011 that we can no longer use gas oil but have to use low sulphur I expect to see an increase in diesel bug due to the 5-10% bio and the fact that diesel on the cut sits in tanks for ages.

 

Do you think a suitable fuel additive will compensate for extra water content + do you know if bio content increases cetane rating? (thinking of Mikuni/Eberspacher/Webasto etc)

[GUMPY]

Do you think a suitable fuel additive will compensate for extra water content + do you know if bio content increases cetane rating? (thinking of Mikuni/Eberspacher/Webasto etc)

 

Not sure, but then as a Mikuni user I am not that bothered since the Mikuni will burn just about anything and yes I have tried lots, including B100!

Having said that it runs best on the "thinner" fuels B100 is a little to thick for the pump.

Tony is the best person for additives IIRC he did a test on some of them.

[Albion]

To go back to the original question.

The high performance diesel will only give you additional fuel savings if your car or boat has an ECU that will adjust the fuelling on the fly.

My BIL has a BMW and he does see a noticeable difference in MPG between normal diesel and the high performance, stuff when I had my diesel polo there was no noticeable difference.

The same applies to super unleaded unless your car has an ECU that will take advantage of it or you have a high performance engine there is very little to be gained by using it.

One final point "City Diesel" contained at last 5% bio diesel as that was the only way that they could get the emissions down far enough to meet the standards. Now almost all diesel sold on forecourts contains between 5 and 10% bio.

When it becomes law in 2011 that we can no longer use gas oil but have to use low sulphur I expect to see an increase in diesel bug due to the 5-10% bio and the fact that diesel on the cut sits in tanks for ages.

 

I'm not entirely sure about whether the ECU adjusts on a diesel Julian. It certainly does on a petrol engine where the ECU keeps advancing the spark up to the knock point and then backs off until the knock sensors no longer detect knock, then advances again and backs off again and so on. The sensors are detecting knock (commonly called pinking) that is inaudible to the human ear. In this case the quality of the fuel (it's resistance to early knock) will definitely allow the engine to be run more advanced and extract more power per stroke.

 

In the case of a diesel the ambient noise is much greater, knock discrimination is harder and, from when I worked in engine management, I don't remember knock sensors being used for that same purpose. That's not to say that they haven't been added since, as it is 5 years since I got out of diesel engine management.

Roger

[Trilby Tim]

Do you think a suitable fuel additive will compensate for extra water content + do you know if bio content increases cetane rating? (thinking of Mikuni/Eberspacher/Webasto etc)

Yes, I'm pretty sure Bio does have a higher cetane rating.

[nb Innisfree]

I'm not entirely sure about whether the ECU adjusts on a diesel Julian. It certainly does on a petrol engine where the ECU keeps advancing the spark up to the knock point and then backs off until the knock sensors no longer detect knock, then advances again and backs off again and so on. The sensors are detecting knock (commonly called pinking) that is inaudible to the human ear. In this case the quality of the fuel (it's resistance to early knock) will definitely allow the engine to be run more advanced and extract more power per stroke.

 

In the case of a diesel the ambient noise is much greater, knock discrimination is harder and, from when I worked in engine management, I don't remember knock sensors being used for that same purpose. That's not to say that they haven't been added since, as it is 5 years since I got out of diesel engine management.

Roger

 

I was under the impression that common rail diesels adjust injection timing to reduce smoke caused by overfuelling, when we hire a diesel car I now find it impossible to make engine smoke by revving hard after a period of slow running whereas it was normal on older diesels. Not knock sensors but I think they have smoke sensors which achieve similar results?

[Albion]

I was under the impression that common rail diesels adjust injection timing to reduce smoke caused by overfuelling, when we hire a diesel car I now find it impossible to make engine smoke by revving hard after a period of slow running whereas it was normal on older diesels. Not knock sensors but I think they have smoke sensors which achieve similar results?

 

Common rail diesels inject more efficiently as they use piezo-electric activated injectors which can give up to about 5 injections per combustion (they can open and shut so much faster than the old solenoid type of injector). This is used to control diesel knock as they inject a small quantity first to initiate combustion and then follow that up with further injections to complete that one combustion process. They can also inject late for purposes that I will describe below.

Since Euro 4 and the later Euro 5 emissions requirements have come in most diesels have to have a catalysed diesel particulate filter (DPF for short) in the exhaust system. This collects and stores diesel particulates. When the back pressure builds up across the DPF, measured by pressure sensor differences fore and aft of the DPF, it initiates a burn to burn off the particulates stored. This is achieved by injecting late in the combustion stroke. The unburnt/partially burnt fuel hits the catalysed DPF and temperatures in it is massively raised to the point where an after-burn takes place, the soot is burnt off and you start all over again. This process is only initiated above a certain road speed and at full engine temperature so that the drive-ability of the car is not impaired. This after-burn process typically occurs about every 6 or 7000 miles depending on various factors. Unfortunately, if you are a little old lady dithering about only in the City of London, for example, the DPF can be loaded but the conditions of speed and temperature not met so a light comes on telling you to get out on the open road and get going or to take it to your dealer for action.

Roger

Edited to add that smoke on common rail diesels is reduced because they inject at a much higher pressure than pre-common rail. This atomises the fuel much more efficiently and so the droplets are smaller, the combustion of those droplets is more complete and, hence, less particulates (ie soot which is really partially burnt 'droplets' of fuel).

Edited January 25, 2010 by Albion

[nb Innisfree]

Common rail diesels inject more efficiently as they use piezo-electric activated injectors which can give up to about 5 injections per combustion (they can open and shut so much faster than the old solenoid type of injector). This is used to control diesel knock as they inject a small quantity first to initiate combustion and then follow that up with further injections to complete that one combustion process. They can also inject late for purposes that I will describe below.

Since Euro 4 and the later Euro 5 emissions requirements have come in most diesels have to have a catalysed diesel particulate filter (DPF for short) in the exhaust system. This collects and stores diesel particulates. When the back pressure builds up across the DPF, measured by pressure sensor differences fore and aft of the DPF, it initiates a burn to burn off the particulates stored. This is achieved by injecting late in the combustion stroke. The unburnt/partially burnt fuel hits the catalysed DPF and temperatures in it is massively raised to the point where an after-burn takes place, the soot is burnt off and you start all over again. This process is only initiated above a certain road speed and at full engine temperature so that the drive-ability of the car is not impaired. This after-burn process typically occurs about every 6 or 7000 miles depending on various factors. Unfortunately, if you are a little old lady dithering about only in the City of London, for example, the DPF can be loaded but the conditions of speed and temperature not met so a light comes on telling you to get out on the open road and get going or to take it to your dealer for action.

Roger

Edited to add that smoke on common rail diesels is reduced because they inject at a much higher pressure than pre-common rail. This atomises the fuel much more effiently and so the droplets are smaller, the combustion of those droplets is more complete and, hence, less particulates (ie soot which is really partially burnt 'droplets' of fuel).

 

Fascinating stuff, thanks for that.

 

Can't beat modern technology IMO and this is early days, exciting to think what will be available in the future, hope I'm still around to see it

[Naughty Cal]

Fascinating stuff, thanks for that.

 

Can't beat modern technology IMO and this is early days, exciting to think what will be available in the future, hope I'm still around to see it

 

Diesel engines with no glow plugs, who would have thought that 10 years ago?

[nb Innisfree]

Diesel engines with no glow plugs, who would have thought that 10 years ago?

 

Not sure but I seem to recall the first British diesel with direct injection and therefore no glowplugs was the Montego in the early 90s?

[Naughty Cal]

Not sure but I seem to recall the first British diesel with direct injection and therefore no glowplugs was the Montego in the early 90s?

 

Not common place though.