Some time ago, I promised ( see www.honestjohn.co.uk/forum/post/index.htm?v=e&t=18...9 )to run an experiment running my car on Optimax for the edification of the backroom gang. I've complained often enough that I've never seen a scientific test of "quality" vs supermarket fuels; I offer the next best thing, an utterly unscientific test.
Premise:
There is a benefit in fuel economy to be had using Shell Optimax petrol.
Equipment:
One 1999 Vauxhall Omega 2.5CDX, mileage 85,000, almost exclusively run on Tesco fuel - Clubcard points!
One credit card (Tesco)
Lots of Shell Optimax
The M3, M25 and A3 mainly.
Method:
Fill car to brim with Optimax (from as near empty as I dare). Drive 3281 miles that match usual driving mix as far as possible.
Fill car to brim with Optimax (at the same pump in the same garage)
Work out fuel consumption
Results:
Used 107.3 Gallons, equalling a fuel consumption of 30.6mpg
Usual consumption of car is 31mpg, so this is probably within errors an unchanged fuel consumption.
Conclusions:
For my car, for my mix of driving (mainly motorway) Optimax offers no fuel consumption benefits.
Discuss.
V
PS. I reckon the Optimax over Tesco has cost me £24 extra. Any chance of a virtual whip-round?
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No problem - here is my virtual contribution
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Did you perceive any performance improvement?
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Did you perceive any performance improvement?
None at all. The car drove and felt exactly the same.
I only really remembered that I was on Optimax when it came to time to refill. And that involved one rather dry-mouthed trip down the last twenty miles of the M3 running on fumes.
V
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apprently you notice it on performance engines, which id say the omega is being a 2.5 litre.
it costs 2p more per litre but does more to the gallon so actually works out the same to run as normal unleaded.
above *facts* ive found off some guy on the web who had a 328i bmw. id go for the tecso + clubcard points and a shot of redex in the tank!
dont believe the hype, fuel is expensive enough as it is
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Don't believe the hype, he says. Then he proposes a shot of Redex in the tank! (Which I use(d) to replace lead in an old Merc, but that's rather different.)
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I don't know much about Omega engines but I'd imagine that with all the anti-pinking measures built into modern engines, is there a possibility that the engine may have adjusted the ignition timing slightly and negated the effect?
I don't know what effect that would have though if this is even a valid assumption to make.
I use Optimax with a few doses of various esoteric additives for my classic as it is supposed to have a higher octane and LRP is almost totally unobtainable. Even the little village garage opposite Pinewood Studios has stopped selling Bayford Thrust now :(
My personal experience is a lot less scientific but compared to ordinary unleaded with additives there less of a flat-spot on the power band between 2,000 and 3,000 rpm and it does seem to pick up with slightly more urgency.
The engine is a 1972 V8 3.5L albeit with after-market Weber twin carbs. I get anything from 25mpg to 16mpg depending on my driving hence the lack of definite figures.
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I've got a magnet you can clip round the fuel line, if you'd like to borrow it. Magnetises the fuel molecules making them flow smoother and burn quicker! LOL!
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But if you put the magnet on the wrong way round it reverse polarizes the molecules making them flow in a more turbulent manner and thus burn more slowly!
Although an even less scientific test than Vin's my experience on a Golf 1.8t over a few tankfulls with Optimax was much the same.
And Optimax costs more than an extra 2p a litre round here, 5-6p
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I work at a very large, very busy oil refinery (not shell !!!) and every possible tanker collects petrol and delivers over a large part of england. the only company which I have not seen is esso because they have a terminal down the road. so the two grades produced (premium & super) are distributed identically except for the additives put in after the tanker has filled up at the road loading stand. this includes shell, bp, texaco, tesco, sainsbury, etc. etc.
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When I did the same experiment I also saw no difference at all. Some people say that if your engine has an anti-knock sensor it can take advantage of Optimax. (Mine doesn't.)
Optimax is also claimed to keep the engine internals cleaner, which might be a benefit (if it's true) if you intend to keep the car for a long time.
I've gone back to using whatever 2 star happens to be there when I need it, mostly Shell or Texaco as they are the filling stations at either end of my daily commuting route.
I've had people swear to me that those magnet things really work. Sorry, but they stay in my 'snake-oil' folder until I see proof.
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And don't forget that if the magnet doesn't give you more mpg, you can always use it on the house plumbing to get rid of limescale, or put it round your wrist to ward off rheumatism, or put in in your garden pond to kill algae, etc., etc., etc.
Back to reality ... I think Vin made a good job of testing Optimax. It wasn't a fully scientific back-to-back test but was as good as could be expected in the circumstances. Thanks for that, Vin.
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But if you'd used a Shell PlusPoints card, you'd have saved nearly 2p/litre.
& if you'd used the Shell credit card, yet ANOTHER .7p/ litre!!
VB
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they sell those magnetic things on QVC. save the £30 and buy a tank of fuel instead!!!!!
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vin{p} says
" For my car, for my mix of driving (mainly motorway) Optimax offers no fuel consumption benefits ."
vinp what does your car operating manual sspecify?
if it says use premium 95 ron than that is all you need.
my book says use super ron 97 or better.
so that is what i use. the cheapest around my travels is sainsbury's 97 ron.
if i cant get to them, i use texaco super or shell optimax.
but not because they claim to be superior.
only because they sell super whereas most other garages dont.
kev the rev says
" so the two grades produced (premium & super) are distributed identically except for the additives put in after the tanker has filled up at the road loading stand. this includes shell, "
i think this may be incorrect. why? because
shell claim that optimax is produced at a single shell refinery and sent fully ready for the pump storare tanks.
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"vinp what does your car operating manual sspecify?
if it says use premium 95 ron than that is all you need."
No idea what it says; I've always just run it on standard unleaded - it's not a highly stressed engine or anything.
I ran the experiment because I've heard a great deal of talk about whether different types of fuel do make a difference. I've asked a dozen times whether there has ever been a scientific test (where are Which? when you need them - after all, fuel must be one of the most significant purchases many people make in a year). In the absence of a formal test, I volunteered to run this slightly less formal version.
I have no axe to grind. Even though I'm dubious about all the "branded petrol good, tesco petrol bad" chating that goes on, I would truly have preferred it if the experiment had shown Optimax to be worth buying - it would have saved me money and would have allowed me to use the most convenient petrol station to my house.
As it is *for me* (and I stress that again) it doesn't make sense.
V
PS, the {P} in a profile isn't part of our names; it just means that our profile is public
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vinp says
"I've asked a dozen times whether there has ever been a scientific test (where are Which? when you need them"
vinp
sounds like you dont need 98ron but
i found the following on google, dont know if it answers your q?
www.millersoils.net/pdf_downloads/Millers_octane.p...f
homepage.ntlworld.com/johnnya/max-boost/fuelling.h...e
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It all depends on compression ratio and whether the ignition timing is set for the octane level used. Try an 80's mk.2 golf with the timing set back for 95RON, and put where it should be or slightly advanced on optimax- its a noticeable difference i can tell you, as much as 5bhp (this engine is rated at 139bhp). My mum's old 850 T5 runs better on Optimax- she gets about 1-2mpg more on it which in percentage terms is quite a difference as she used to get only 16-17, and now she gets 18-19. I dont think the vauxhall has a map for 98RON fuel. A friend used to have a Carlton gsi 24v and that was not mapped for 98RON. Turbo charged engines in particular may benefit from the better fuel.
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One tankful is hardly scientific is it ?. Anyone who uses Optimax regularly will tell you it takes two or three tankfuls to "clean" the engine and only a small amount of a lower octane petrol will drop the octane level of any higher octane petrol added. I use Optimax regularly (how did you guess) and due to all the disbelief in it, I thought that I would go back to normal unleaded to see if it made a difference or was I imagining it. It did make a difference !. On the first tankful of normal Shell unleaded I thought that the car did not seem to drive any different but the fuel consumtion went up by about 4%. The second tankful of normal and the car lost its perkiness and didn't seem to have as much low speed torque, the consumtion again was 4% more than on Optimax. To give it a fair chance I tried another tankful of normal and it was the same again. I then switched back to Optimax and it took three tankfuls before the perkiness came back and the consumption dropped by 4%. The cost of Optimax is about 4% more than normal unleaded where I live, so the gains in fuel consumtion on Optimax are cancelled out by the extra cost. The perkiness and cleaning of the engine by the additives is the attraction for me. Maybe some engines are more suited to the increased octane rating and if it doesn't work for you then stick to the normal unleaded, but it works for me ;-) I drive a 2.5 V6 Mk3 Mondeo.
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Kith
read the bit where Vin said he
"Used 107.3 Gallons"
More than a tankfull i think - He did an extensive test and it didnt work for him, you cant argue that - it didnt work for him.
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Kith read the bit where Vin said he "Used 107.3 Gallons" More than a tankfull i think - He did an extensive test and it didnt work for him, you cant argue that - it didnt work for him.
Doh! apologies Vin, as I said in my post though, it does work for me. ;-)
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Are the engine cleaning additives in Optimax the same as in standard Shell unleaded? My Ibiza takes 95RON petrol, and won't take advantage of anything more. If Optimax increases performance and cleans the engine, would I be right in assuming that the high octane adds the performance factor, while the Shell detergents do the cleaning?
Regarding performance cars, my 1988 Saab 900 turbo 16S that I owned up until last year (I still miss it) had a noticeable performance drop if I went back to even 97RON after running it on Optimax. I ran it on Optimax for the time I had it between 175,000 and 205,000 miles, and the car wore out before the engine (Aside - the car didn't wear out completely, but got uneconomical to repair). The manual for this car recommended 97RON and above, and the engine had a knock sensor that adjusted the ignition timing.
Economy-wise, I couldn't say. The higher performance encouraged me to push it harder, negating any benefit. I was more concerned with performance than economy, however.
BogStandard
Seat Ibiza 1.4S
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see my reply link to millers test results.
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Forget it on Fords with Zetec engines - no knock sensor..
Personally I think magnets are a waste of time.. just wait for a full moon and do 3 circles round the car widdershuns chanting "more mpg, more mpg, this car must get more mpg"
Works as well as magnets and Optimax:-)
madf
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BTW, my 'magnets post' was a joke, I really wasn't being serious.
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WHAT! I have sent off the cheque now.............
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Really!
I have been experimenting with a 240v Electro-magnet. It works great on tickover but I find the range of my car limited by the power lead.
I'll have to run it by LAC for his thoughts.
C
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"Forget it on Fords with Zetec engines - no knock sensor.."
Really, madf?
I have no evidence to back this up other than my own calculations, but my '95 1.6Zetec Escort 'jumped' from 32 to 35 mpg average as soon as i started using Optimax. No discernable performance improvement, but most certainly improved mpg, both the brim to brim calcs and the range i can get show this to be so.
As where i am 'normal' petrol is 93p and Optimax 97.5p, with my consumption increase Optimax is economically the better option
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Well done Vin. I, too am a doubting Thomas on this one...but to be consistent, I must be suspicious about your experiment as indeed I am of any opinion on fuel expressed in the BR.
I am an advocate of HJ's many pieces of motoring advice and this has served me well. Hence I do use Shell (diesel) - on his advice - but have to say this is one area about which I would like to see more objective evidence. I personally think that you can make yourself think that one type of fuel or another additive makes a difference whereas in actual fact nothing may have changed. That's no scientific test. If shell and texaco really are that much better, then great but let's see the evidence and please lets make it objective and scientific, not anecdotal and a matter of opinion...
Splodgeface
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"If shell and texaco really are that much better, then great but let's see the evidence and please lets make it objective and scientific"
That's what I was trying to do, within the constraints of not having a couple of identical engines, a fully equipped engine testing lab, etc, etc.
My conclusions are probably OK, though as I must stress, they only apply to my car on my type of journey. Doubtless if I get a Lexus (see other recent thread) I'll get the chance to do the experiment again in the hope that it'll save me some cash.
V
PS perhaps if 50 backroomer types did the same experiment, the results might begin to represent a decent sample.
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And remember Vin these 50 Backroomers must have the Optimax substituted for their normal fuel without them knowing, any worthwhile test must be blind when the user can influence the result to such a great degree.
I find the greatest improvement in smoothness and mid-range pull is always after washing the car and cleaning the interior.
M.M
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For what it's worth, I have asked Which? if they will embark on tests and a user survey, not just on Optimax, of course, but encompassing all the "premium" fuels. Don't hold you breath, but you never know.
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Shell Optimist:
Here is how I can get 2.17 MPG more by not buying Optimist;
Equipment: Nissan Almera 1.8SE Auto. (Requires 95 RON)
Minimal use of Air Con. (it?s winter)
Journey: 1 mile of urban sprawl and 16 miles of motorway or 18 miles of country A roads
Average MPG over 5 tank full of ordinary 95 RON unleaded from Texaco, Tesco and Sainsburys : 32MPG, average cost 73.5p/litre (£3.34/Gallon).
In my location Optimax is 78.5p/litre, so
Per tank full
54.5 Litre x 78.5p=£42.78
54.5 Litre x 73.5p=£40.06p
Difference is £2.72 or 0.814 gallons x 32 MPG = 26.05 miles,
26.05 miles, / 12 gallon tank = 2.17 MPG
Hence the money I save by not buying Optimist will buy me enough fuel to equate to a 2 MPG increase using ?ordinary? 95 RON.
As mentioned before, driving style has a big influence on MPG. So will the traffic conditions and journey type.
As I was disappointed with 32 MPG I checked the air filter, it was dirty enough to replace and I did so about 50 miles after brimming the tank. To check what difference the filter would make I refilled again to the brim, and to my surprise I found that the 50 miles (pre-filter change) gave 38 MPG. That 50 miles had no motorway in it so I concluded that the stop/start portion of my motorway mileage really ate the fuel. Post filter change it returned 33 MPG.
I think brimming the tank is accurate enough, probably +/- 50cc (0.01 gallons) because I always like to see the stuff in the pipe before I stop filling. That means 0.02 x 32 MPG = 0.62 miles of inaccuracy. Anyway I see 400 miles to the next refill regularly now. My next experiment after this tank full will be to trash it everywhere (but not jabbing the throttle to get a burst of speed), using the revs and kickdown to get to speed quickly then holding steady throttle where possible. Reasoning here is that free breathing 16V engines may perform better by that method. We shall see.
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Hawsey
No knock sensors on Zetec engines.. No , none.. not one..
Ford saving money:-)
madf
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So whilst i haven't noticed any performance improvement, is my car unable to improve mpg aswell??? Coz i swear it leapt up 3 mpg!
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And remember Vin these 50 Backroomers must have the Optimax substituted for their normal fuel without them knowing, any worthwhile test must be blind when the user can influence the result to such a great degree. I find the greatest improvement in smoothness and mid-range pull is always after washing the car and cleaning the interior. M.M
Otherwise known as the slipper effect. ;)
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Having a knock sensor isn't enough - not all EMS systems are calibrated to take advantage of higher octane fuel when it is used.
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while looking up slick50 claims on the u.s. federal trade commission web site, i found the following regarding fuel additives.
www.ftc.gov/os/1999/09/shellconsent.htm
www.ftc.gov/opa/1999/09/shellcastrol.htm
In the latest of a series of Federal Trade Commission cases alleging that ad claims for motor oil and fuel additives were deceptive, Castrol North America Inc., the marketer of gas additive Castrol Syntec Power System, and Shell Chemical Company, the developer and supplier of the Castrol Syntec Power System?s active ingredient, have agreed to settle FTC charges. Castrol is charged with deceptively advertising on television, in magazines, and on the product?s label, that Castrol Syntec Power System significantly improves engine power and acceleration and is superior to other gas additives; and with falsely claiming that tests prove these claims. Shell is alleged to have provided its trade customers, like Castrol, with allegedly deceptive advertising and promotional materials, and to have made allegedly false or misleading representations about tests it conducted on its VEKTRON? 3000 fuel additives. Based on these actions, Shell is charged with providing the "means and instrumentalities" to its trade customers to deceive the public.
www.ftc.gov/opa/1997/09/exxon.htm
"Many consumers buy high octane gas believing it is a 'treat' or a 'treatment' for their cars," said Jodie Bernstein, Director of the FTC's Bureau of Consumer Protection. "But it's the consumers getting the treatment, not the cars. Most cars don't need and won't benefit from hi-test gas, so paying extra for premium gas is wasting money," she said. "Now Exxon will join the FTC and the American Automobile Association to get the word out to consumers: Unless your owner's manual calls for high octane fuel or your engine is knocking, there's no reason to pay for premium gasoline," she said. "This is a precedent-setting law enforcement remedy that will save American consumers money."
In September 1996, the FTC issued a complaint charging Exxon with making unsubstantiated advertising claims about the ability of Exxon gasoline, including Exxon 93 Supreme, to clean engines and reduce auto maintenance costs. As part of a consent agreement to settle the charges, announced for a public comment period in June, Exxon agreed to produce a 15 second television ad featuring an Exxon official who will say, "Most cars run properly on regular octane, so check your owner's manual and stop by Exxon for this helpful pamphlet."
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