Guys,
Having read the following: m http://www.spyderchat.com/phpBB/viewtopic.php?t=5492 (http://www.spyderchat.com/phpBB/viewtopic.php?t=5492) m I was beginning to worry if regular use of Shell Optimax could eventually lead to the problems that this person has described...? s:shock: :shock: s:shock: s:shock: :shock: s:shock:
The issue is apparently carbon build-up which can cause the engine to misfire and a loss of power... s:!: :!: s:!: s:!: :!: s:!: s:!: :!: s:!: s:shock: :shock: s:shock:
Is anyone aware of this? Should I be worried and stick to standard Unleaded as a precautionary measure s:?: :?: s:?: I'd hate to be contributing to a future problem...
Thanks in advance,
Sundance s8) 8) s8)
I've said this before but no body agreed so I shut up. Use what Toyota recommend, using something lower is a bad idea, but regularly using something higher could also cause problems.
To much is just as bad as to little. Of course I could be wrong, but then none of use really know why this happens.
Do any cars actually say that you should use the higher 97/98 ron fuel? If not then why sell it? If its going to damage your car then surely people like BP & Shell would be in and out of courts defending thier product from screwing up god knows how many cars?
I dont know, i was actually thinking of starting to bring my car slowly off this as its starting to get pricey round here now s:? :? s:?
Quote from: "krisclarkuk"Do any cars actually say that you should use the higher 97/98 ron fuel? s:? :? s:?
Plenty, the S2000, NSX, 911's, 350Z, Exige, i'm just picking at these off the top of my head.
I could see some of the higher spec cars wanting this... but would they then say that you CAN run on lower but you shouldnt as it may damage your engine? Thing is, i can see a lot of people not being able to get easy access to the higher ron petrol as not every garage does it, so surely the manufacturers would allow for you to use a lower rating (or higher in our case)?
I dont know, just thinking/typing out aloud! s:wink: :wink: s:wink: s:lol: :lol: s:lol: s:oops: :oops: s:oops:
<edit> kinda on that note... some manufactuers also tell you not to use additives like injector cleaner etc in their cars, but the companys that make this stuff say its fine to use in all cars....? which company is right there? s:crazyeyes: :crazyeyes: s:crazyeyes: </edit>
The Audi TT specifies 98RON too.
If it were me... I'd be less inclined to believe the marketting put out by Shell, and more inclined to stick to what the manual tells me to put in the car. There are some things where I know what the effect will be, and somethings I don't. Fuel is one of them.
Surely any modern car, which an adaptive ECU & knock sensor will be any RON fuel, within reasonable tolerances. I have used Optimax exclusively for about 15,000 miles now without any problems.
My personal experience of experimenting with fuels has lead to me deciding to use Optimax based on various experiences and advice.
--H--
Quote from: "phil4"The Audi TT specifies 98RON too.
If it were me... I'd be less inclined to believe the marketting put out by Shell, and more inclined to stick to what the manual tells me to put in the car. There are some things where I know what the effect will be, and somethings I don't. Fuel is one of them.
I totally agree, I don't believe anything Shell tells me, the 1ZZ was designed to run on a lower fuel over here and i'm sticking to it. Normally I wouldn't worry, but on a engine with a unsolved problem i'm not pushing my luck. Its getting to be a pain in the ass this CAT problem, even for those of us withOUT the problem yet, its like you have to watch your every move...
Quote from: "WoodenDummy"I totally agree, I don't believe anything Shell tells me, the 1ZZ was designed to run on a lower fuel over here and i'm sticking to it. Normally I wouldn't worry, but on a engine with a unsolved problem i'm not pushing my luck. Its getting to be a pain in the ass this CAT problem, even for those of us withOUT the problem yet, its like you have to watch your every move...
What CAT problem? s:? :? s:?
Quote from: "krisclarkuk"Quote from: "WoodenDummy"I totally agree, I don't believe anything Shell tells me, the 1ZZ was designed to run on a lower fuel over here and i'm sticking to it. Normally I wouldn't worry, but on a engine with a unsolved problem i'm not pushing my luck. Its getting to be a pain in the ass this CAT problem, even for those of us withOUT the problem yet, its like you have to watch your every move...
What CAT problem? s:? :? s:?
...the...cat...problem...you know...exploding cat...boom goes the engine...thing...
The problem SC has a poll over every month....
Quote from: "WoodenDummy"...the...cat...problem...you know...exploding cat...boom goes the engine...thing...
The problem SC has a poll over every month....
did know about that.
Stay away from SC really. SC = Loads of yanks doing nasty things to their '2's... s:? :? s:?
s:lol: :lol: s:lol:
er... but we DO have engine/cat problems. Cases in England/US/Japan all over.
Quote from: "WoodenDummy"er... but we DO have engine/cat problems. Cases in England/US/Japan all over.
sorry typo above - should have said didnt, not did! s:oops: :oops: s:oops:
Surely the onus ought to be on the manufacturer (i.e. Toyota GB) to have a separate page in their manual descibing the car's compatiability with all the different types of fuel?
I doubt very much that Shell have done long term testing of Optimax with every type of car manufactured in the last 10 years - it would take too long (and cost too much)!
Does anyone have any conect details for s:evil: :evil: s:evil: s:evil: :evil: s:evil: Toyota Customer Services s:evil: :evil: s:evil: s:evil: :evil: s:evil: ? Perhaps I can take the matter up with them..?
Sundance
<edit>Ooops forgot my shades - here they are ----> s8) 8) s8) </edit>
Just to throw my 2p in, I've used it for a while now and not had any problems, but I take on board the comments about long-term issues. Asking Toyota might not be a bad idea Sundance, but I expect they will say don't use it as let's face it, it's the easy answer s:? :? s:?
Hmmm.... I guess its like in IT where the supplier says "our product only works with IE5.5 SP1, running JRE version x.x.x etc etc" - as this is the only configuration that they have bothered testing their product with... s:( :( s:(
Sundance s8) 8) s8)
Well, Shell have replied to the email I sent - judge for yourselves:
Dear Sir.
Thank you for your recent e-mail.
I was very concerned to hear what you have been told about Shell Optimax. Please be assured that Shell Optimax is suitable for all vehicles designed to run on unleaded petrol, it has been tested extensively and will not cause any damage whatsoever to your vehicle.
Shell Optimax is a unique highly refined new formulation which burns more cleanly to give you smooth power delivery. It is able to do this becuase:
* as the petrol with the highest octane rating in the UK it enables advanced modern design engines to work more efficiently thereby delivering more power
*it has the ability to remove performance sapping deposits left by other fuels from the airways of the engine
*it is free of the heavy constituents of petrol that leave dirty residue in you engine.
The combination of these effects means that the fuel and air flow smoothly and quickly to the engine, burning more effectively to give you increased performance and a quicker response.
If you require any further information then please do not hesitate to contact our Customer Service Centre on our free phone number 0800 731 8888.
Regards,
Kathryn Baillie
Retail Customer Relations
Shell U.K. Oil Products Limited
Rowlandsway House, Rowlandsway, Manchester M22 5SB, United Kingdom
Tel: +44 161 947 5523 Fax: +44 161 499 8088
Email: e http://www.shell.com/uk (http://www.shell.com/uk) m
Interesting - nice one.
Is anyone collecting the card thingys i need an X5 wheel , a bmw M3......... ill split the winnings with a match s:lol: :lol: s:lol:
Quote from: "Sundance"Well, Shell have replied to the email I sent - judge for yourselves:
Dear Sir.
Thank you for your recent e-mail.
I was very concerned to hear what you have been told about Shell Optimax. Please be assured that Shell Optimax is suitable for all vehicles designed to run on unleaded petrol, it has been tested extensively and will not cause any damage whatsoever to your vehicle.
Shell Optimax is a unique highly refined new formulation which burns more cleanly to give you smooth power delivery. It is able to do this becuase:
* as the petrol with the highest octane rating in the UK it enables advanced modern design engines to work more efficiently thereby delivering more power
*it has the ability to remove performance sapping deposits left by other fuels from the airways of the engine
*it is free of the heavy constituents of petrol that leave dirty residue in you engine.
The combination of these effects means that the fuel and air flow smoothly and quickly to the engine, burning more effectively to give you increased performance and a quicker response.
If you require any further information then please do not hesitate to contact our Customer Service Centre on our free phone number 0800 731 8888.
Regards,
Kathryn Baillie
Retail Customer Relations
Shell U.K. Oil Products Limited
Rowlandsway House, Rowlandsway, Manchester M22 5SB, United Kingdom
Tel: +44 161 947 5523 Fax: +44 161 499 8088
Email: e http://www.shell.com/uk (http://www.shell.com/uk) m
You see this is the bull crap we have to put up with. Using Optimax is not going to give a car designed to run on a lower RON more "performance". A Jap import might run smoother, but not a UK Spec MR2, it might be cleaner (Super unleaded cleans anyway). IT might burn cleaner but it also might burn hotter.
Have Shell run a MR2 on Optimax for 60k miles? No. Can they prove that running a petrol higher than normally recommended by Toyota on a engine with un resolved problems with heat etc will not damage the engine. No. Can I prove it will? No. Which is why I stick with what i'm told until someone works out how to fix the exploding cat problem.
I'm not bad mouthing Optimax, I've used it the odd time i'm just not buying the advertising crap s:roll: :roll: s:roll:
Quote from: "WoodenDummy"Have Shell run a MR2 on Optimax for 60k miles? No. Can they prove that running a petrol higher than normally recommended by Toyota on a engine with un resolved problems with heat etc will not damage the engine. No.
Same reason I'm not going to change. Shell
would say it's brilliant and safe, but as they can't prove it doesn't do damage, I'll stick with the fuel that the manufacturers have tried for 60K miles, and do know doesn't knacker the engine. Saying it's been tested extensively, doesn't mean it's been tested on my car for 60K miles.
I'm not convinced by what Shell say... but it would be interesting to hear what Toyota say! Personally, my car's full of Optimax at the moment... but it's only through this thread that I've heard of the cat problems... not yet sure what I'll put in next. s:? :? s:?
Having said that, I've now taken a look at the SC discussion, and of those that have had problems the vast majority appear to be using fuel with a RON rating lower than 95. Does it follow that you'll also get the same problems by going higher than 95? I guess no-one knows, so maybe it's best to play it safe. I've got about a week before I need to fill up again... guess I'd better take a closer look at SC before then!! s:? :? s:?
Rough translation from the ADAC website
http://www.adac.de/auto_motorrad/kraftstoffe/test_shell_v_power/default.asp?id=0
QuoteGeneral German Automobile Association (ADAC)
test 2003: Shell "v-power" in test
Full one 100 oktan flow from the v-power - pistol.
In comparison: "super" has 95, super plus 98, and the "Optimax" 99. New additives for engine-cleaning and a "Friction Reducer". The purpose being to reduce friction between piston ring and cylinder.
The noble juice costs at least nine cent to more per litre than with the competition (super plus) - well invested money? A reason for the ADAC to examine under the magnifying glass, the sprit that the Schumi brother Michael spoke of ("... the best drive, I ever...") .
How we did the test
How do engines designed for 95 or 98 octain run with 100 octain?
The ADAC set three representative vehicles, which need 98 oktan, alternatively with conventional super plus and with new v-power to the test standard and drove with them practice attempts similar to the ADAC autotest:
an AUDI A3 2,0 FSI as modern direct injection,
a BMW 316i with variable valve gear
the Porsche Boxster as sports cars with a high efficiency (162 KW) engine.
As a fourth test candidate a VOLKSWAGEN golf 1,4 16V was examined, which needs 95-Oktan-Super.
The Results.
The results are sobering with only the VOLKSWAGEN and the Porsche having a slight increase in output power? However, this was clearly below two per cent and thus within the measuring tolerance. And five per cent more torque? Again no return: All the results showed outside of statisticaly measurable tolerances but sometimes with worse results
Due to the results of measurement, and the heafty surcharge, there was no incentive to use this fuel in our test vehicles.
Here was a table to be seen at http://www.adac.de/auto_motorrad/kraftstoffe/test_shell_v_power/default.asp?id=0
So who needs the new superfuel? If the vehicle industry is to be believed : nobody. So argue auto makers, the knocking sensors of current engines would be appropriate for at the most 98 oktan and could not use a 100-Oktan-Potenzial under standard conditions at all.
In all other respects does competitor Aral refer to the fact that "innovative" additive additives had already been added for four years and naturally without surcharge.
That's interesting.
After only being able to fill up with Optimax at Oxford Services last Friday, I have conducted my own totally non-scientific comparison. With my new 03 '2 only really covering motorway miles since completing the first 600 miles of 'gentle running' it has been returning 40-45 mpg on average. A tank of Optimax returned about the same - 39 mpg. Given that it's just about impossible to ensure that the same amount of fuel goes in each time I fill up, I would say that this is within the margin of error.
As for power/torque increases, I haven't noticed any, but my MK1 lard-a***e isn't the most sensitive of scientific instruments s:D :D s:D , plus I haven't stretched the car much beyond 4000 rpm (yet).
I filled up on Optimax again earleir this week, just to make sure there wasn't too much cooking unleaded left in the mix in the tank, and I'm interested to see if the mpg figures compare when I fill up again over the weekend.
What is real is the pain in my wallet, with a litre of Optimax being 4-6p dearer than cooking unleaded, depending on where you buy it.
I think that there is a big discrepancy with the argument with this. I have had experience with both the Mk1 and the new Mk3 and I have to say both have been VERY different.
The Mk1 had VERY significant performance changes with Optimax. I don't have scientific figures on this, but I can tell you that it was a definate change. You really could feel the engine freeing up and revving freer, as well as a slight increase in acceleration and decrease in engine noise. Like I said, this is not scientific as such, but I had people in the car who rode with me to work and even thety said they could feel the difference with the Optimax compared to the 97RON Super from BP that I normally filled up with from the station near work. Oh, and this may be important (well, I think it is!) but the Mk1 had well over 100K miles on the clock.......
Whereas the Mk3 has had no significant performance improvements since I have been putting it in. None that I can tell of anyway, other than maybe a little difference in the smoothness of revving. The economy has been within a 4-5mpg with any type of fuel that I put into the Mk3. My Mk3 has only 13K on the clock.....
So, from my very unscientific experiments and deductions, I reckon that the Optimax DOES have an effect on the car, but it probably has something to do with the wear and tear, as well as the condition of the engine for when it makes its difference. The the 4-AGE engine was a pretty advanced engine for its time back in 83-84 when it was launched and with 100K on the clock, perhaps the supposed benefits claimed by Shell would probably have a much more magnified effect by bringing the engine up to some kind of performance level. On a much more modern engine with very little milage and wear, I reckon the effects would be much less significant.......
So, whatever fuel you put in, I reckon it makes not one jot of difference at this age and stage of wear of most of our relatively new technology engines........
Put what you want in. I don't think it will make a blind bit of difference.....
Just my 2 penneth worth!!!
I've never put optimax in mine, but that's just because i'm a skin flint and don't like paying for something that's probably all in the mind anyway!
Besides, as has been mentioned, if Toyota wanted to run on that, then they would say so.
I've heard of the engine problems, but hadn't heard it put down to the cats before - I thought it was an oil leak that was contaminating the cats?
Has anyone actually checked their owners manual?
Mine just says anything 95 RON or above is fine.
Quote from: "markiii"Mine just says anything 95 RON or above is fine.
Apparently it runs just fine even with 91 octane from Russia (at least the same engine in Corolla does). Probably loses some power, but no major issues anyway. Then again, I think every car with a knock sensor should run with lower octane...
Anyway, here's a dyno of my stock engine after about 2 months of "learning" with 98E (that's roughly 99 octane and should be similar to Optimax):
m http://koti.mbnet.fi/temmeke/tmp/dyno.jpg (http://koti.mbnet.fi/temmeke/tmp/dyno.jpg) m
I can only assume the +9hp comes from the fuel...
Well my previous car I had for 40,000 miles never used anything but Optimax, as with the 2. It's correct that you can only get a performace adv up to a point, the mapping on the ECU is not configured for anything much higher than 98 ron.
The Higher the RON number though, effectively the better anti-knock properties the fuel has (prevents pinking). This will let the Anti-knock sensors / ECU advance the ignition timing as much as possible without the pistons melting, this in turn provides more power because the pistons are nearer Top Dead Centre and therefore not fighting the piston coming up as much.
What makes me continue to use it is a test EVO did on Optimax, I think EVO are one of the most unbiased mags out there at the mo.
They tested Optimax on 3 of their fleet cars (Civic Type-R, Jaguar XJR, BMW M-Coupe). Shell claims that Optimax 'cleans' the inlet valves of the engine and that heavy constituents in other fuels can leave deposits on the backs of the inlet valves with the poorest quality fuels leaving the most which can lead to a tar like gunge within a 1000miles (EVO, 2002).
In order to form an objective test as possible EVO placed cameras into the inlet tracts to determine if any deposits were present. Their test was to run the cars on 'other' unleaded fuels for 1500 miles and then use exclusively Optimax for a further 1500 miles before taking further pictures of the inlet valves. EVO also recorded the cars' in-gear performance figures before and after the test.
Interestingly when EVO took the initial inlet valve pictures the Civic had the most deposits. This car had been using cheap supermarket petrol (so take heed!). The BMW and Jaguar were relatively clean using a variety of SU and regular unleaded.
The inlet valve pictures showed a marked improvement especially on the Civic whose inlet valves were rid of deposits entirely. The other two cars had very clean valves before the test so results were less marked. For the performance figures the best results were again on the Civic with a loss of 1.19 seconds for 60-80mph in fifth. The drivers of the cars all reported smoother running and a more responsive engine. EVO's verdict? Shell's Optimax does what it says it does, leading to smoother running, increasing performance and preventing build-up of performance-sapping deposits.
(Sorry didn't have a link only the mag in front of me!)
Quote from: "Mikeharper2"advance the ignition timing as much as possible without the pistons melting, this in turn provides more power because the pistons are nearer Top Dead Centre and therefore not fighting the piston coming up as much
When you advance the timing, doesn't that move the ignition time to earlier point...meaning the piston is further from the TDC...?
You would need to rolling road and advance the timing like you say to get the maximum effect. To be honest I don't buy it for the performance aspect more the cleaning aspect, and I have to admit thats pretty subjective too. The EVO test was a good indicator of this but again that was only a 1000 miles, after a few thou more it might go wonkey.
Thinking about it the mechanic who works on my old mans skyline said not to put Optimax in for some reason saying it ran too rich with it. Seemed a bit strange but he was pretty adamant.
Quote from: "Tem"When you advance the timing, doesn't that move the ignition time to earlier point...meaning the piston is further from the TDC...?
If I'm correct then no, because;
The timing is actually set BTDC.. So say the timing is at -15deg, advancing it (mathematically speaking, kinda) actually means moving it to say -13deg (so you're increasing the number), so you actually move it closer to TDC.
If the base timing was ATDC, then it'd all be the other way around.
Ideally, if I recall, the timing should be set so that the advancing flame front reaches the cylinder crown just as it begins to drop away from top dead centre..
Timing is confusing s:D :D s:D
Quote from: "Mikeharper2"Thinking about it the mechanic who works on my old mans skyline said not to put Optimax in for some reason saying it ran too rich with it. Seemed a bit strange but he was pretty adamant.
And the moral of that is not to believe most of what mechanics say s:) :) s:)
I know ! and this guy is a racing mechanic that works on the GT car. Don't know what he was on that day. Talking about Optimax i'm off to get some right now, nice day roof down me thinks
Quote from: "Mikeharper2"I know ! and this guy is a racing mechanic that works on the GT car. Don't know what he was on that day. Talking about Optimax i'm off to get some right now, nice day roof down me thinks
Mind if I ask which garage? Just you saying he's a racing mech makes me wonder if it's one I have heard of (and have in mind) s:) :) s:)
And.. nice day? It's peeing down with rain here! s:evil: :evil: s:evil: s:) :) s:)
Ah, you're right aaron...I mean both of you s8) 8) s8)
Higher octane means the fuel withstands more compression before self ignition...and more compression is achievef by letting the piston go further...
Think Tem, Think s:lol: :lol: s:lol:
Quote from: "Tem"Think Tem, Think s:lol: :lol: s:lol:
s:D :D s:D
Every time anyone mentions ignition timing my brain starts to hurt!
Quote from: "aaronjb"The timing is actually set BTDC.. So say the timing is at -15deg, advancing it (mathematically speaking, kinda) actually means moving it to say -13deg (so you're increasing the number), so you actually move it closer to TDC.
If the base timing was ATDC, then it'd all be the other way around.
Nope, you're thinking of advancing the wrong way.
Your basically right, typical timing is set in degrees BTDC, but moving towards TDC is retarding, not advancing the timing. This is because the spark will happen later (retarded) when the timing is moved towards TDC. That's why knocking occurs when timing is too advanced (too early) - the piston is not yet on it's way back down from the compression stroke.
Think of the spark in relation to time, not TDC.
Quote from: "Tem"Higher octane means the fuel withstands more compression before self ignition...
Erm.. yes, but compression is fixed by the relation of piston to head
Quote from: "Tem"and more compression is achievef by letting the piston go further...
Erm.. no.
The pressure within the cylinder increases massively when the fuel burns and the gasses expand (that's where you get the power from). If the piston is further past TDC, travelling downwards, when the expansion is at its fiercest then there is less likelyhood of knock as there is more volume between the piston crown and head.
Quote from: "mrbarney"Erm.. yes, but compression is fixed by the relation of piston to head
I just meant that the compression increases as the piston moves upwards squeezing the A/F mixture...like...if you ignite at 90 degrees BTDC you'll have less compression than igniting on the TDC...
Had to Google a bit s8) 8) s8)
m http://auto.howstuffworks.com/ignition-system1.htm (http://auto.howstuffworks.com/ignition-system1.htm) m
And seems my first thought was right after all. Advancing means igniting earlier...and retarding later.
My old man has worked in the car trade all his life so when I was up at his garage yesterday I asked him about this Optimax fuel. He told me that there is currently problems with it long term whereby its doing internal damage to certain engine valve guide seals and injectors. He advised not to go near the stuff while they having problems with it.
Quote from: "heathstimpson"My old man has worked in the car trade all his life so when I was up at his garage yesterday I asked him about this Optimax fuel. He told me that there is currently problems with it long term whereby its doing internal damage to certain engine valve guide seals and injectors. He advised not to go near the stuff while they having problems with it.
Cheers heath... was going to do a 1000 miles with it to clean things up, but think I'll wait now s:) :) s:)
standard shell is supposed to have the same detergents, just not the octane rating.
26,000+ miles from new solely on the stuff which I appreciate is too little to be considered 'long term' but no apparent problems with the engine yet. I have also been using Mobil 1 0W-40 since 10K so am doubly damned s:P :P s:P
I did get a lovely red Ferrari sportbags from my Optimax Club membership though s:) :) s:)
In my case I reckon the biggest risk to my car's engine is the driver and his driving style s:wink: :wink: s:wink:
Quote from: "heathstimpson"My old man has worked in the car trade all his life so when I was up at his garage yesterday I asked him about this Optimax fuel. He told me that there is currently problems with it long term whereby its doing internal damage to certain engine valve guide seals and injectors. He advised not to go near the stuff while they having problems with it.
More accurately, it does a very good job of keeping seals clean. The 'issue' isn't Optimax itself, but switching to it after using crap for years. The more aggressive cleaning agents will start removing the built-up deposits around seals that weren't being removed by the poor cleaning agents and that's when problems can start.
I have never joined in with this coversation before, cos I dont understand it all. I just use super unleaded all the time and stay away from Tescos. However today we where nearly on empty (yep we had the 2 out again with the top down!!!).
And happened upon a garage with Optimax in it (shell aint it). SO thought why not. Filled up.
Now I am not really sure if there was a difference, as I was driving it particually hard today on the dual carrigeways, but I am SURE it did feel different somehow, maybe its in my mind?
I've used Supermarket fuel for convenience but have heard some horror stories about the rubbish in it compared to the big name fuels s:shock: :shock: s:shock:
when the snow came i was forced to fill up an a supermarket... they had super plus 97 ron so i used that, but that tank of petrol the car felt rough as hell... could have just been in my head but it didnt feel right. Put optimax back in as soon as i could!
not you rimagination.
the long term fuel map learns. When you surprise it it takes a while to re-adjust
Quote from: "markiii"not you rimagination.
the long term fuel map learns. When you surprise it it takes a while to re-adjust
Do you know how much difference there is between say a decent standard Shell fuel and Tescos s:?: :?: s:?:
Shell fuel = spending sh*t loads on a top-notch vindaloo at a top-notch curry house with 20 other members of MR2 ROC on a perfect sunny day in the middle of summer.
Tesco fuel = having a cheap own-brand microwave curry in a squat, then realising you don't have a microwave...or cutlery.
Hows that for a comparison?
Basically most supermarkets use well know suppliers of fuel, I work for Morrisons and we use Texaco - it's just rebranded. However the suppliers add different addatives for different garages. So a supplier delievering to their own chain will use the best addatives they can. When they deliever to a supermarket chain the addatives will not be as good.
This is why supermarket petrol - Tesco, Morrisons, Safeway, Sainsbury etc - is sooo much cheaper than the major garages - Shell, Texaco, Q8 etc. Sometimes by over 4p per litre.
Basically you pay for what you get. 76.9p for unleaded or 85.9p for Shell Optimax.
Quote from: "heathstimpson"Quote from: "markiii"not you rimagination.
the long term fuel map learns. When you surprise it it takes a while to re-adjust
Do you know how much difference there is between say a decent standard Shell fuel and Tescos s:?: :?: s:?:
not sure how t quantify it to be honest. Strange how my car always feels better running esso?
How do the big boys compare then s:?: :?: s:?: Shell, Esso, BP, Texaco, Total etc
it's been said to me that every engine has it's own preferences and I'd tend to agree.
it's what feels best to you.
Personally
Esso
Shell
Texaco
BP
But thats based upon regular a i don't user super very pften.
Quote from: "heathstimpson"How do the big boys compare then s:?: :?: s:?: Shell, Esso, BP, Texaco, Total etc
Gold = Shell
Silver = Esso and BP (BP's new fuel could push them up and knock Shell down)
Bronze = Q8 and Texaco
Then the rest.
Q8?
Quote from: "markiii"Q8?
There were a couple of Q8 garages around when I lived in Birmingham, but I can't say I've seen a single one in Shropshire... evidently they aren't common down south either!
This is an interesting topic. I use supermarket petrol in my Type R but every so often i tank up with optimax. The only things i've noticed are that with optimax the car seems to run a tad smoother but no faster.
Geoff. s:) :) s:)
Hi there everyone,
New user here, we only just collected our '00 MR2 Roadster yesterday and what a great little motor it is. s:lol: :lol: s:lol:
We've not had much of a chance to throw any fuel in it as yet, so I cannot give you an opinion on the use of Optimax in the MR2.
But when it comes to my GTO Twin Turbo, I use absolutely nothing else unless absolutely necessary. The lads over at the GTO owners club ( w www.gtouk.org (http://www.gtouk.org) w ) will tell you this also. The machine will run quite happily on normal unleaded and the ECU very quickly determines the change in octane, but I do notice a substantial drop in performance and decrease in MPG. s:( :( s:( (and I don't like this, it's bad enough anyway)
However, it is a much older engine to that of the MR2, both physically and in design.
My general rule fuel preference is
Shell Optimax
BP Ultimate
Esso Super Unleaded
Super Unleaded from any other forecourt when the above are not available.
Justin
Unless you've modified the engine (ie ECU / compression), there is no benefit to running super unleaded: the stock ECU simply doesn't adjust to any noticable degree the timing values.
However, manufacturers tend to put their highest quality additives in their super, and this will have a bearing, not necessarily in the short term, but over a much longer period. Cleaner valves and less carbon build up with help with airflow.
Note, lower octane petrols invariably have higher calorific values and of course a faster flame-front - meaning they release more energy just at the right moment. Something to think about when if you're trying to get 100octane race fuel into your 1ZZ-FE..
I wasn't actually suggesting that I would run Optimax in the Roadster (it's the other half motor anyway), just that it has made a considerable difference to the performance of the GTO, which is a 3.0 litre Twin Turbo charged beast.
The evidence is clear from datalogging that has been performed.
Quite how it affects the 1.8l engine found in the MR2.... I don't know.
Justin
Quite - it's when you get in the land of forced induction (or to a lesser degree, have cranked up the timing) is when octane is important.