Tesco diesel

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You might however notice improvements in responsiveness or smoothness around gear changes, unless you're driving a diesel where differences due to similar (but still different) fuels are more subtle.

When I drive, I mentally envision an imaginary coin stood upright on the bonnet, and my goal is to arrive at my destination with the coin still upright :)
 
1. My late father-in-law used to be a fuel oil distributor based in the Fawley refinery at Southampton. His office overlooked the tanker filling area and he was always going on about the fact that every tanker filled up from the same hose, be they Esso, Asda, Texaco etc.
They do but doesn't each tanker have a tag of some sort that tells the system what additives to dose to the delivery?
 
When I drive, I mentally envision an imaginary coin stood upright on the bonnet, and my goal is to arrive at my destination with the coin still upright :)
Araldite works very well ....
 
So, come back with the facts and they can be teased out.
OK...

"When the air fuel mixture ignites by the heat of compression rather than because of the spark from the spark plug, it causes knocking in the engine and a loss of power. The knocking sound is caused by two exploding "flame fronts" - one explosion from the pre-ignition of the fuel-air mix caused by compression and the other from the rest of the fuel-air being ignited at a slightly different time by the spark plug. The two flame front explode and send shock waves through the air of the cylinder, which meet in the combustion chamber and give you that annoying knock effect."
Simply not what happens.

Pre-ignition is not caused by compressing the fuel:air mixture. Instead it is caused by a hot-spot or glowing ignition source in the combustion space, such as glowing carbon deposits, or perhaps the wrong grade of spark plug that doesn't cool sufficiently between firing cycles. In addition, pre-ignition is an uncontrolled combustion rather than an explosion. It starts at a given point and spreads through the combustion charge and may even have time to consume the whole charge before the spark occurs. However as it occurs very early in the cycle while the piston is still rising in the bore, the resulting pressure spike can be very high, resulting in a heavy 'mechanical' knocking sound as the much higher forces get reacted out through the piston and con-rod. Fuel octane quality does not affect or control pre-ignition and neither does ignition timing. Pre-Ignition under load is extremely damaging, and within a few seconds, maybe a few minutes depending on severity can result in engine failure, ie. broken pistons, holes in the piston, bent con-rods, damaged big-end and/or main bearings.

Pinking, detonation or knock happens after the spark, where a portion of the air:fuel mixture ahead of the main flame front becomes trapped in part of the combustion space. These end-gases get compressed by the main flame front and become over-heated to the point where an explosion occurs. All of the remaining end-gas detonates at the same time. The very high speed pressure waves produced in the explosion are heard as a light 'pinking' sound which is not the sound of the two flame fronts colliding at all. Because knock happens in the end-gases after the spark, the piston is moving down the bore so the space is getting larger, and pressure spikes are more mild than they are with pre-ignition.The good news is that reducing combustion chamber pressure by retarding the ignition timing or by using fuel with higher octane rating helps to prevent the end-gases from detonating.

The main concern with knock is the disruption to the insulating boundary layer in the combustion space, which can result in some damage to the piston crown or elsewhere. Typically this is light damage, but if allowed to continue for extended periods (and for some engines this can be hours and hours), then a hot-spot can develop which can then lead to pre-ignition. This a strong reason for avoiding knock in the long term. Another reason is that customers don't like it and another is that the combustion even is less efficient when knock is present.

"So, octane does not enhance the explosion in the cylinder like most people think."
The main combustion in an engine is not an explosion, it is a burn initiated by the spark plug and progresses across the combustion chamber at a few tens of metres/second.

"What does octane do? It just prevents the air-fuel mixture from igniting before the spark plug does it."
No it doesn't.


"Using higher-octane gasoline than your engine is designed to utilize is only wasting your money."
The only part of the article that is correct.


All this discussion on octane is a bit irrelevant for this thread really, as the original topic was about diesel.
 
I have an OM646 engine with a Brabus chip in mine , and run it on Sainsbury's diesel most of the time, only the occasional Branded fuel if I have to refuel on a motorway, has worked well for me for the last eight years.
Anyone know if the D3S box increases power on any 646? Or if I already have the 646evo with 170bhp will it not make any difference?
The d3s box ups power from 170 to 217bhp and torque from 400 to 460nm
 
Great variety of posts with loads of accounts of different fuels but my original post was why does my diesel Mercedes w204 c220 cdi with a om646 engine run noticeably smoother on regular Tesco diesel, I have tried all makes and varieties of fuels and additives but Tesco fuel runs smoother and with less noise, do i have a fault somewhere or just lucky that my car likes cheap fuel⛽
 
Can we have some sort of list from best to worst in terms of retailers and the additive packages though?

By using high-frequency forecourts and ideally ones which look like they’re relatively new, you would hope that the storage tanks are in good order and the fuel supplies are fresher. The local Tesco’s filling stations are usually very busy... :D

I fully appreciate what is said about the quality of the additive packages but I still would like to know who uses what, who is good and who to avoid. Without this information - other than assuming all supermarkets sell poor quality fuel and all ‘major’ filling stations only sell top quality fuel (markjay’s point about M&S will have to be overlooked here..) how do you know where to buy from and who’s to say what you’re getting for your money other than all retailers selling fuel that meets the spec mentioned earlier?

How does Tesco Momentum compare with standard grade from say Shell or BP and what’s better? :thumb:
 
Great variety of posts with loads of accounts of different fuels but my original post was why does my diesel Mercedes w204 c220 cdi with a om646 engine run noticeably smoother on regular Tesco diesel, I have tried all makes and varieties of fuels and additives but Tesco fuel runs smoother and with less noise, do i have a fault somewhere or just lucky that my car likes cheap fuel⛽
Seems like the current (Tesco) fuel you're using has less ignition delay than the fuels you've used in the past. This could be due to a number of factors. Without knowing more about the specific fuel(s), it's pretty hard to say exactly why.
 
I fully appreciate what is said about the quality of the additive packages but I still would like to know who uses what, who is good and who to avoid. Without this information - other than assuming all supermarkets sell poor quality fuel and all ‘major’ filling stations only sell top quality fuel :thumb:

Supermarkets do not sell poor quality fuel period!

ALL fuel sold in the UK meets the UK standard and this has been discussed over and over and explained by several members who clearly have significant knowledge and expertise on this subject far above that of nearly every other member.
 
Can we have some sort of list from best to worst in terms of retailers and the additive packages though?

How does Tesco Momentum compare with standard grade from say Shell or BP and what’s better? :thumb:
I really don't think there is a definitive list.

When I was last involved in the process, we 'auditioned' additive materials/technologies from all of the main suppliers and chose/recommended the best performing package to the business. During the process, we also blind tested finished fuels sampled from our competitors. In the end I thought we chose the right package.

I've been retired five-years though and this was a number of years before I retired, so things may well have moved on since then.

Just go with a high volume forecourt and you can't go too far wrong.
 
OK...

"When the air fuel mixture ignites by the heat of compression rather than because of the spark from the spark plug, it causes knocking in the engine and a loss of power. The knocking sound is caused by two exploding "flame fronts" - one explosion from the pre-ignition of the fuel-air mix caused by compression and the other from the rest of the fuel-air being ignited at a slightly different time by the spark plug. The two flame front explode and send shock waves through the air of the cylinder, which meet in the combustion chamber and give you that annoying knock effect."
Simply not what happens.

Pre-ignition is not caused by compressing the fuel:air mixture. Instead it is caused by a hot-spot or glowing ignition source in the combustion space, such as glowing carbon deposits, or perhaps the wrong grade of spark plug that doesn't cool sufficiently between firing cycles. In addition, pre-ignition is an uncontrolled combustion rather than an explosion. It starts at a given point and spreads through the combustion charge and may even have time to consume the whole charge before the spark occurs. However as it occurs very early in the cycle while the piston is still rising in the bore, the resulting pressure spike can be very high, resulting in a heavy 'mechanical' knocking sound as the much higher forces get reacted out through the piston and con-rod. Fuel octane quality does not affect or control pre-ignition and neither does ignition timing. Pre-Ignition under load is extremely damaging, and within a few seconds, maybe a few minutes depending on severity can result in engine failure, ie. broken pistons, holes in the piston, bent con-rods, damaged big-end and/or main bearings.

Pinking, detonation or knock happens after the spark, where a portion of the air:fuel mixture ahead of the main flame front becomes trapped in part of the combustion space. These end-gases get compressed by the main flame front and become over-heated to the point where an explosion occurs. All of the remaining end-gas detonates at the same time. The very high speed pressure waves produced in the explosion are heard as a light 'pinking' sound which is not the sound of the two flame fronts colliding at all. Because knock happens in the end-gases after the spark, the piston is moving down the bore so the space is getting larger, and pressure spikes are more mild than they are with pre-ignition.The good news is that reducing combustion chamber pressure by retarding the ignition timing or by using fuel with higher octane rating helps to prevent the end-gases from detonating.

The main concern with knock is the disruption to the insulating boundary layer in the combustion space, which can result in some damage to the piston crown or elsewhere. Typically this is light damage, but if allowed to continue for extended periods (and for some engines this can be hours and hours), then a hot-spot can develop which can then lead to pre-ignition. This a strong reason for avoiding knock in the long term. Another reason is that customers don't like it and another is that the combustion even is less efficient when knock is present.

"So, octane does not enhance the explosion in the cylinder like most people think."
The main combustion in an engine is not an explosion, it is a burn initiated by the spark plug and progresses across the combustion chamber at a few tens of metres/second.

"What does octane do? It just prevents the air-fuel mixture from igniting before the spark plug does it."
No it doesn't.


"Using higher-octane gasoline than your engine is designed to utilize is only wasting your money."
The only part of the article that is correct.


All this discussion on octane is a bit irrelevant for this thread really, as the original topic was about diesel.
This post deserves to be The Post of 2018.
Well done Sir, only if possible I would give you two Likes.
 
I use from various places but I regularly give a shot of additive.
 
Supermarkets do not sell poor quality fuel period!

ALL fuel sold in the UK meets the UK standard and this has been discussed over and over and explained by several members who clearly have significant knowledge and expertise on this subject far above that of nearly every other member.

Yes I know that, but it seems not everyone does (as per post #24 on this thread)

What I am interested in, is which retailers sell the fuel with the best additive packages (say for standard grade unleaded as a benchmark)

Although those in the know are aware that some of the additive packages they put into fuels are superior to other retailers, how is a consumer to know which filling stations are selling better/worse fuel?

Do all the supermarkets use lower spec/lower performing additive packages? Do all the non-supermarket retailers use the same/similar better ones?

How else do you know exactly what you’re buying? Or do you just put trust in a logo/brand?

It would be easier to compare value for money if you knew what you were getting for your money and which stations sold better/worse products. If you’re selling a better product why not specify what’s in it? :)

As an example people are happy to pay more for say V-power or Momentum (and the benefits are generally well advertised) but on standard grades between different filling stations there really doesn’t seem to be as much information out there?
 
I can only contribute drawing on my DIY experience from the days before cars had any electronics (apart from the radio).

To adjust the ignition timing (if you did not have a strobe to hand that is... or a Sun engine tune-up computer) you would loosen the bolt securing the distributor, then rotate it slightly in one direction. Secure the bolt, drive the car, readjust, repeat, until perfect.

If the car was 'pinking', you'd retard the ignition a touch. If the car was backfiring, you'd advance the ignition a bit.

The sweet spot was when backfiring on the overrun was minimal, and very mild pinking could be heard when picking-up slowly from very low rev at high gear.

Fasten the alternator securing bolt, and you are good to go.

(I am not old enough to have driven cars where the ignition timing could be adjusted from a lever in the dashboard or on the steering wheel)
 
Yes I know that, but it seems not everyone does (as per post #24 on this thread)

What I am interested in, is which retailers sell the fuel with the best additive packages (say for standard grade unleaded as a benchmark)

Although those in the know are aware that some of the additive packages they put into fuels are superior to other retailers, how is a consumer to know which filling stations are selling better/worse fuel?

Do all the supermarkets use lower spec/lower performing additive packages? Do all the non-supermarket retailers use the same/similar better ones?

How else do you know exactly what you’re buying? Or do you just put trust in a logo/brand?

It would be easier to compare value for money if you knew what you were getting for your money and which stations sold better/worse products. If you’re selling a better product why not specify what’s in it? :)

As an example people are happy to pay more for say V-power or Momentum (and the benefits are generally well advertised) but on standard grades between different filling stations there really doesn’t seem to be as much information out there?
The short answer is: The consumer doesn't know which fuel additives are better than others.

The slightly longer answer is: Outside of a fairly small group of engineers, technicians and fuel scientists engaged in the process of evaluating these products, very very few know which additives are better than others. It costs a lot of money and requires talented people with complex expensive equipment to make the determination. The information is unsurprisingly commercially sensitive and is not widely divulged and for good reason.

Bottom line is, notwithstanding screw-ups in supply, pretty much all of the fuel supplied via official U.K. forecourts is fit for purpose. If you find a brand that you're happy with, I'd suggest sticking with it. Being able to demonstrate brand loyalty may pay off if you do encounter fuel related issues.
 
The short answer is: The consumer doesn't know which fuel additives are better than others.

The slightly longer answer is: Outside of a fairly small group of engineers, technicians and fuel scientists engaged in the process of evaluating these products, very very few know which additives are better than others. It costs a lot of money and requires talented people with complex expensive equipment to make the determination. The information is unsurprisingly commercially sensitive and is not widely divulged and for good reason.

Bottom line is, notwithstanding screw-ups in supply, pretty much all of the fuel supplied via official U.K. forecourts is fit for purpose. If you find a brand that you're happy with, I'd suggest sticking with it. Being able to demonstrate brand loyalty may pay off if you do encounter fuel related issues.
Which do you use?
 
I work p/t at a Sainsburys Petrol station. 3 of the Flexigrid tanker drivers out of Grays, Essex, who cover the whole of the South East of England fill up at Sainsburys. They or us do not get any discount on fuel. I asked one of them about this subject.

His answer is that all the 95 RON stuff is the same regardless of whether it's branded Tesco, BP, Shell, Texaco or Sainsburys. He says that the premium 99 RON stuff does differ between brands, with the difference being accounted for by differing proportions of additive and detergents.

There is no mystical set of switches on a tanker which deposits additives into the underground tanks.

So, it's probably fair to say that BP Ultimate and Shell V Power have better additives and detergents than say Sainsburys Super U/L (which is 97 RON anyway). I suspect that Tesco Momentum 99 is an equivalent to BP Ultimate or Shell V Power, but I have no proof.
 

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