Supermarket Fuel, Facts Please

[Howitzer]

manracer said:

Anyone who says they get better range/mpg on one fuel or another when doing comparison tests on the road is kidding themselves and anyone who chooses to believe them because ultimately you cannot say that your comparisons were in a controlled environment with identical conditions, you just can't. Same weather, same temperature, same traffic conditions, same throttle application - it's just not possible.

I've tried and it's no where near accurate enough to be a comparative test. There are far too many variables.

Untrue, if you take into account your driving and back to back tests you can get a very good comparison. You can’t tell if a difference is 4 or 7% etc but you can easily tell by sound, start up, smoke, fuel economy etc whether one fuel is working better than another.

I did my apprentiship on Diesel engine testbeds. Currently work for a company doing installation, commission8ng and repair on medium speed diesels so fuel economy and how the engine runs is part of my job.

Now, on my donkey diesel Defender 200tdi I’ve tried a few fuel Types and home brew mixes. Despite its low up/litre I spend much more time in much higher load conditions as pushing it through the air at 65mph is actually working it relatively hard.

I don’t know which refineries they use in Peterborough but nearly all my fuel is bought in the area.
Co-op diesel. No issues, a bit rattly on start-up and will smoke off boost quite noticeably till I’ve done a couple of gentle miles. Once warm I have no issues and average 29mpg.

Tesco’s, same as co-op.

Shell normal, same as the above but less smoke when cold.

Shell super diesel, less smoke all over, less diesel knock aswell but worth the extra, not really. I put a few tanks of it through every year as I believe it does help the nozzles.

Morrisons normal diesel, starts nicely but on full boost a constant grey haze not experienced with all other fuels. I’ve done tank after tank of comparisons as we used to save a fair bit with the money off per litre vouchers we got on the weekly shop. Tried this probably about 5 or 6 times over the years with the same result. I also had a stuck wastegate when using Morrison’s diesel and parking it up for a month but that could have happen d with any fuel as if no evidence to support it being just a Morrison’s problem.

I’ve also run a small amount of ep90, auto gearbox oil, fresh rapeseed oil etc but once warm Morrison’s diesel smokes the most.

The biggest cause of issues I have in the marine and power production world is bad quality fuel (either through separators or just bad fuel) causing injector problems or bad low load combustion ruining the oil.

I keep cars a long time and maybe the extra I pay for fuel doesn’t work out as a saving in the long run. I’m not saying what I’m doing is right for everyone but my experience nudges me towards a supposed better quality of fuel/ additive.

[RobM77]

996TT02 said:

RobM77 said:

As a former scientist, I'm well aware of that. However, in practise, if you do the same test for something this simple ten times and get the same result +/- <10% every single time (for example, results could be: 10%, 9.5%, 10.2%, 9.7% etc), statistically that's fairly conclusive (if there is no other plausible reason why you'd get those same results). To minimise the latter, I've measured the mpg in two different ways and guess what? same results again. The likelihood of me achieving those results by chance is vanishingly small. I've even done it for two different cars and yes, same result again. As I allude to above, my primary point was actually referring to the many tests done by others in a more scientific setting and the secondary point was how one's own tests mirror these findings. Your criticism is valid in many contexts, but not in this context - this is a very simple test of how much fuel is used per mile driven, it's not rocket science!


Edited to add: Let's be clear about this and restate what I said above in my first post: for more subtle issues such as Tesco fuel vs Shell fuel I think anecdotal evidence is indeed next to useless, especially when we're looking at reliability, rather than a simple number such as mpg. I agree with you there.

Edited by RobM77 on Thursday 23 August 11:46

Here's the problem with your testing Rob. For starters, I am not doubting your results - I will 100% take your word for them, that you noticed a 10% reduction in consumption on "better" fuel.

The problem is that you were testing, you knew it, and you possibly believed, had an expectation of achieving the result you obtained. This, to cut a long story short, would have affected your driving, even if you were not deliberately making any effort to skew the results - you were chasing the result, and since driving habits have a humungous effect on economy, you obtained it, albeit possibly for the wrong reason.

For such a casual inherently imperfect test to be worth anything at all (apart from being repeated a large number of times) the driver must not be aware of what is in the tank, and ideally nor that a test is being undertaken.

Very true. However I would say that the commute was mostly on cruise control, with no input from me (7 minutes of lanes, 37 minutes of cruise control, then traffic lights and 1 minute of 40mph limit into work, so 18% in my control, 82% not). I rotated between 4 or 5 tanks of VPower and 1 of fuelsave over four years in my last job, which is 73k miles, or about 80 tanks of fuel. I remain sceptical though, which is why I keep doing it every few tanks

Edited by RobM77 on Wednesday 29th August 17:42

[Krikkit]

Limpet said:

My personal belief is that there is a difference between 95RON and 97/99 RON (Super/Momentum/V-Power) that certain engines will be able to take advantage of...

Assuming they have a knock sensor and actually use it, correct!

[GC8]

BAM225 said:

Thesprucegoose said:

diesel and petrol all comes from the same refineries. they add additives that are blended to the relevant spec. (only real difference is biofuel added)

if it makes you feel better to buy it branded as shell etc then do it.

Tried to explain this on pistonheads time and time again, I used to do some work at a fuel refinery in fact, but alas people think that shell and bp use wizzardry to make there fuel better and this thread will almost instantly by tomorrow drag into a arguement.

There are SOME variables though. Particularly tank position that the fuel is drawn from.

[unsprung]

Shakermaker said:

unsprung said:

if retail petrol in the UK is functionally identical across all brands, then at least one of the following statements must also be true:

a) engine performance and longevity are unaffected, whether a brand uses additives or has none

b) although competing brands use unique formulations of additives, the results across these differing formulations are the same

c) the chosen fuel additives have no effect on things like engine performance and longevity -- and are a de facto risk for brands that make marketing claims to the contrary

B would be the most logical to my mind. For all 95-RON fuel, different retailers will have their own unique additives and blends, which will have the same end result, or at least, negligible differences to most users.

In a discussion full of analogies, is it a bit like asking "Is Fairy Liquid better than Tesco Lemon Fresh Washing Up Liquid?" - they do the same thing, but Fairy Liquid purports to be more efficient at doing the same thing, but costs more to do it, but to most people, their dishes still come out clean no matter which they use (or, stay just as dirty) because its not entirely the liquid that does the job, but the manner in which it is used?

so if we're going with option B, then it would appear that:
.

• diverse formulations of retail petrol have no diversity in functional results
• all retail brands take the extra step to add brand-formulated additives... and no retail brands go without these

I don't believe we're prepared to say that these last two points are accurate statements

[unsprung]

RTB said:

Do manufacturers design the longevity of their engines with any fuel additives in mind, or do they test them with fuel that doesn't contain additives?

in that large automotive market on the other side of the Pond, a good number of manufacturers specify both particular brands of fuel to be used as well as a particular class of fuel (ie: fuel that includes additives which go beyond the minimum functionality required by law)

the preceding statement does not refer to octane ratings, but to fuel quality / functionality as determined by the presence of additives added by the retail petrol brand

the manufacturers referenced above include Asian, European and US OEMs

[Mr2Mike]

unsprung said:

in that large automotive market on the other side of the Pond, a good number of manufacturers specify both particular brands of fuel to be used as well as a particular class of fuel (ie: fuel that includes additives which go beyond the minimum functionality required by law)

Specify or recommend?

[unsprung]

Mr2Mike said:

unsprung said:

in that large automotive market on the other side of the Pond, a good number of manufacturers specify both particular brands of fuel to be used as well as a particular class of fuel (ie: fuel that includes additives which go beyond the minimum functionality required by law)

Specify or recommend?

good question

here are the details:
https://en.wikipedia.org/wiki/Top_Tier_Detergent_G...

[Grayedout]

OverSteery said:

Grayedout said:

The base fuels are the same as they come from the same refineries.

The final fuels will perform differently with respect to engine cleanliness and possibly engine performance due to the different addtive packs that are used between different companies.

Will the supermarket fuel cause running problems? - in the short term no but if it does not provide the same levels of cleanliness as say a Shelll V-Power then over time your car will not perform as well as it would have if it has used the higher quality fuel all it's life.

Is this observable on the road? - possibly but there are a lot of factors that also contribute to it.

Grayedout - your statement appears to state that if you use fuels with lower levels of "cleanliness" your engine will not perform as well long term

Do you have any evidence that some fuels offer lower levels of "cleanliness"?
Do you have any evidence that it causes long term effects?
if so what?

[as discussed VPower has a different Ron/Octane]

Evidence that I can publish on a public forum? Unfortunately no. Have I seen performance differences between different fuels in controlled tests then yes huge differences.

What I can do is point you at this European institution who's job it is to control the engine tests that are used to classify the performance of oils AND fuels in Europe. This link is to the list of fuel performance tests that are currently used in Europe https://www.cectests.org/listdoctypeforsale1.asp?s...

My point is if all fuels were the same then there would be no reason for these tests and this organisation to exist !

The same base fuel with a different amount or different type of additive can make huge differences in these tests which will relate to a difference in performance on the roads.

[RobM77]

I'm not sure if this has been mentioned yet, but when Evo magazine ran a fuel test many years ago, one thing they concluded from analysing their fuel samples was that supermarket fuel was fresher, due to the higher throughput of fuel compared with other fuel stations.

Edited by RobM77 on Thursday 30th August 09:15

[FK]

Morning all,

This is a very interesting thread for me, because I recently started a new job that requires me to commute 330 miles per week by car, and at my own expense. So the constant debate began about whether the extra cost of super/shell/premium etc is enough to offset the anticipated mpg increase.

I have to admit that I have been running my mk1 Focus 2.0 on tesco momentum predominantly, then I switched to a bit of Shell V-Power, and now the last couple of tanks have been on Shell normal. I'm really struggling to tell any difference, although it could be that I don't really have the car to recognise any advantages that differing fuels may have.

Having said all of this, I know of several people who have filled up their cars almost exclusively on whatever is cheapest (invariably supermarket fuel), and I'm delighted to report that none of their cars have exploded, or have any bits randomly fall off.

I did watch the 5th Gear piece on the effects of using different fuels, but in my experience this is extremely car dependent

[anonymous-user]

Look at people reporting mpgs, they always report what they think which is usually incorrect. The problem is that when a premium product has so little difference from standard people will subconscious think it is better therefore lie to themselves about it.

[gizlaroc]

MKI Focus 2.0?

Is that a petrol? NA or turbo?

Is it set up for using super unleaded?

[gizlaroc]

Thesprucegoose said:

Look at people reporting mpgs, they always report what they think which is usually incorrect. The problem is that when a premium product has so little difference from standard people will subconscious think it is better therefore lie to themselves about it.

I have seen some differences, but only with cars that are set up for 98ron.

My 335i was obviously better on 98, you could really feel the difference power wise, and average MPG would go from 26.x to just over 30mpg with the 98 stuff.

Same with the E350, from 26mpg average from 70-90k miles using 95ron and the minute I started using 98ron it was over 30mog from the first tank and stayed there for the next 25k miles.

[soad]

gizlaroc said:

MKI Focus 2.0?

Is that a petrol? NA or turbo?

Is it set up for using super unleaded?

Naturally aspirated. He didn't say RS.

[gizlaroc]

soad said:

Naturally aspirated. He didn't say RS.

I don't have a clue about Fords.


I doubt the 2.0 NA is set up for 98 ron is it?

[Deep Thought]

gizlaroc said:

soad said:

Naturally aspirated. He didn't say RS.

I don't have a clue about Fords.


I doubt the 2.0 NA is set up for 98 ron is it?

I would doubt it also.

[TwistingMyMelon]

I run my ford connect on Shell v power diesel or whatever it's called

I don't really look at mpg or notice any difference , it does lead a hard life with a fair few shortish journeys that I can't avoid , hopefully the better quality fuel will help the DPf and Egr .

Ideally I would have had a na petrol but there was no engine option

[Rich Boy Spanner]

Used supermarket diesel in various VW/Skoda TDi's (TDI PD's and common rail) almost 100% of the time since 2004 and never had an issue.
Use Shell V-Power diesel in our 11 year old Corolla Verso as it spends most of its time round town and the EGR valve clags up otherwise (before the diesel police jump in, it wasn't bought as a town car but circumstances changed).

[FK]

Deep Thought said:

gizlaroc said:

soad said:

Naturally aspirated. He didn't say RS.

I don't have a clue about Fords.


I doubt the 2.0 NA is set up for 98 ron is it?

I would doubt it also.

Afternoon,

It's a Mk1 2.0 Petrol Ghia. I would imagine it's not set up for 98 RON or above, and I wasn't expecting the car to suddenly eat 911s and R8s for breakfast. But a few posts on here, and other research I have done, has at least implied that some super unleaded fuels may have additives that keep the engine in a slightly cleaner state.

For the moment it's getting Shell 95 as it's currently priced the same as my local Sains and Tesco, and it's actually on my way to work. Plus I have seen no change in mpg, still getting around 35 or so. But I have nothing against supermarket fuels at all