I saw a 911 C2 today using the filth that is Texaco to fill up his car. None of my friends who drive decent cars (M3 Evo, Honda S2000, Boxster S)and I would ever contemplate using anythin other than Optimax.......are we alone?
Optimax
- Thread starter Rodney Naghar
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You do rather seem to have been taken in by the hype, in my opinion. I use ordinary 95 octane unleaded in my 87 3.2 (I have had the AMD conversion to run on 95, it is true, but only because the car is modified), and have never had any problems, or noticed any difference between makes. I have never tried Optimax (can' t see the point). The way my car drives depends a lot on the weather/temperature, how long since it' s been out, how I feel etc., and not
on the fuel.
Climbs down of soapbox, and has a calming cup of chai.
on the fuel.
Climbs down of soapbox, and has a calming cup of chai.
John,
Perhaps you should try Optimax?
You might be pleasantly suprised!
BTW. All the current model range are designed to work on 98RON fuel. They CAN be run on 95 or 97RON as they automatically adjust the timing to take account of the lower rating, but you WILL lose performance because of this. Whether this loss is noticable or not is perhaps debateable.
Perhaps you should try Optimax?
You might be pleasantly suprised!
BTW. All the current model range are designed to work on 98RON fuel. They CAN be run on 95 or 97RON as they automatically adjust the timing to take account of the lower rating, but you WILL lose performance because of this. Whether this loss is noticable or not is perhaps debateable.
BTW John, Love the avatar!
Mark
Mark
Didn' t notice much difference between Optimax and 95 unleaded in my Audi S3 but am trying Optimax in the Boxster at the moment, partly because I' m taken in by the advertising hype (it' s like expensive waxes, probably no more effective than cheaper ones but they' re more expensive so must be better!) and partly because my local petrol station sells Shell! Will share the results when available.
I think its the fact that it' s the only petrol close to 98 RON and has cleaning additives. Its not really the enhanced performance I' m after, more the reduced guilt!
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It may be true that the current range needs 98 octane, but, as mine is older and re-mapped to take 95, then that is what it gets.
Three things also come to mind:-
1. I remember the fuss some years ago when one of the majors in the petrol business produced a ' special' petrol, which they had to take off the market as, it seemed, a lot of Vauxhall (I am sorry to demean this site with such a word, but I have said it now) engines suffered major problems when using it.
2. When I had my SC, which used to run on the old 2 star, I got very funny looks in garages when I filled it with 2 star. They just couldn' t associate a sports car with ' poor' petrol; it ran fine for many years, with no engine problems.
3. The assumption must be that all modern cars are designed to run on 95 or 97 unleaded, as these are the two main choices, with 97 being a bit less common.
So, expecting 98 seems a bit much for a modern manufacturer.
ps Mark, my avatar was just me playing around with a bit of software that I had, and a free movie I found, and ending up with something rather neat (OK, self praise, and all !)
Three things also come to mind:-
1. I remember the fuss some years ago when one of the majors in the petrol business produced a ' special' petrol, which they had to take off the market as, it seemed, a lot of Vauxhall (I am sorry to demean this site with such a word, but I have said it now) engines suffered major problems when using it.
2. When I had my SC, which used to run on the old 2 star, I got very funny looks in garages when I filled it with 2 star. They just couldn' t associate a sports car with ' poor' petrol; it ran fine for many years, with no engine problems.
3. The assumption must be that all modern cars are designed to run on 95 or 97 unleaded, as these are the two main choices, with 97 being a bit less common.
So, expecting 98 seems a bit much for a modern manufacturer.
ps Mark, my avatar was just me playing around with a bit of software that I had, and a free movie I found, and ending up with something rather neat (OK, self praise, and all !)
At the PCGB Silverstone track day last year (2002) I almost managed to get to the end of the day without filling up with petrol. Too lazy to leave the circuit I decided to put £25.00 of racing fuel (107 octane I think) in my GT3. I did 5 laps of Silverstone and it was gone so £5.00 a lap!!!!!
Oh and the best bit...it made NO difference whatsoever.
Won' t be doing that again.
Normally fill up with super unleaded or Optimax for track days but run normal unleaded otherwise. If a GT3 engine runs OK on it most Porsches designed to run on unleaded should. According to Dyno figures from Parr garage the engine runs smoother thats it, no noticeable gain in BHP.
GARY
GT3 register secretary PCGB
Oh and the best bit...it made NO difference whatsoever.
Won' t be doing that again.
Normally fill up with super unleaded or Optimax for track days but run normal unleaded otherwise. If a GT3 engine runs OK on it most Porsches designed to run on unleaded should. According to Dyno figures from Parr garage the engine runs smoother thats it, no noticeable gain in BHP.
GARY
GT3 register secretary PCGB
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The drivers manual (handbook) that came with my car says the following:
The engine is designed to provide optimum performance and fuel consumption if unleaded premium fuel with 98 RON/88 MON is used.
If unleaded premium fuels with octance numbers of at least 95 RON/85 MON are used, the engine' s knock control automatically adapts the ignition timing.
This applies to C2, C4, C4S, manual and tiptronic versions, with and without engine upgrade.
I can' t speak for the GT3 or Turbo.
This is clearly ambiguous. They imply you should use 98 but say it does no harm to use 95.
When I picked up the car, the salesman mentioned I could run it on 95, in fact even recommended I do. His view was that it was up to me if I wanted to spend more money but it would not make any difference.
Since they are likely to get the car traded in in a few years, I can' t believe they would recommend anything that could do any long term harm.
When brand new I got 16 mpg while driving gently home. Now it is run in I get around 27 mpg commuting along the M3 at 85-95 (although I can get it substantially lower if I try around some of the B-roads). I have been using Esso super unleaded and Optimax while running it in, since it ran smoothly and I thought the optimax detergents would help while I was running it in since I was driving more slowly.
However, now I plan to change to 95. I may use the optimax stuff every 5th fillup or something to keep the injectors clean, but since it does almost no town driving I am not sure it really needs it. I' ll let you know if it makes a difference to the consumption figures.
Octane ratings make no difference to power output, as long as there is no pre-ignition or pinking.
I prefer to use branded fuels (Esso, BP, Shell) rather then supermarkets since I am not convinced the supermarket fuels contain the same additives. I am pretty sure this was true 5-10 years ago when they supermarkets started, but may just be prejudice on my part now.
Of more significance to your engines health will be ensuring the correct oil level and topping up with the correct grade. Additionally, regular usage and avoiding high revs (>4000) and full throttle while cold, will be far more important than the petrol.
Rgds, Stuart.
The engine is designed to provide optimum performance and fuel consumption if unleaded premium fuel with 98 RON/88 MON is used.
If unleaded premium fuels with octance numbers of at least 95 RON/85 MON are used, the engine' s knock control automatically adapts the ignition timing.
This applies to C2, C4, C4S, manual and tiptronic versions, with and without engine upgrade.
I can' t speak for the GT3 or Turbo.
This is clearly ambiguous. They imply you should use 98 but say it does no harm to use 95.
When I picked up the car, the salesman mentioned I could run it on 95, in fact even recommended I do. His view was that it was up to me if I wanted to spend more money but it would not make any difference.
Since they are likely to get the car traded in in a few years, I can' t believe they would recommend anything that could do any long term harm.
When brand new I got 16 mpg while driving gently home. Now it is run in I get around 27 mpg commuting along the M3 at 85-95 (although I can get it substantially lower if I try around some of the B-roads). I have been using Esso super unleaded and Optimax while running it in, since it ran smoothly and I thought the optimax detergents would help while I was running it in since I was driving more slowly.
However, now I plan to change to 95. I may use the optimax stuff every 5th fillup or something to keep the injectors clean, but since it does almost no town driving I am not sure it really needs it. I' ll let you know if it makes a difference to the consumption figures.
Octane ratings make no difference to power output, as long as there is no pre-ignition or pinking.
I prefer to use branded fuels (Esso, BP, Shell) rather then supermarkets since I am not convinced the supermarket fuels contain the same additives. I am pretty sure this was true 5-10 years ago when they supermarkets started, but may just be prejudice on my part now.
Of more significance to your engines health will be ensuring the correct oil level and topping up with the correct grade. Additionally, regular usage and avoiding high revs (>4000) and full throttle while cold, will be far more important than the petrol.
Rgds, Stuart.
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Stuart
You are correct about the supermarkets - they did, in the past, offer cheaper petrol as they left out some of the additives; whether these ' left out' additives actually were useful is a debatable point, as petrol is sort of aimed at the lowest common denominator, your average family saloon (they make up the majority of the market, no snobbery intended).
Nowadays, the supermarket petrol is cheaper due to bulk buying - there are many more supermaket outlets per chain - and the fact that it can be used as a ' loss leader' , to get you into the supermarket itself, where the real money is.
Yes, sympathetic use of the car - gentle when cold, occassional blasts when warm to burn off the sediments in the oil etc. must do more good than fancy petrol.
I still maintain that 95/97 octane must be what car manufacturers build their cars for; there is no Optimax in Europe, after all. Suggesting 98 makes them seem special/high performance/a cut above the ' ordinary' car&driver.
We seem to have forgotten that Porsche has got the name it has due partly to it' s engineering excellence, strength and reliablity (one of the reasons I bought my first) - who else has won the big race 16 times, when the Japanese have only won once ?
You are correct about the supermarkets - they did, in the past, offer cheaper petrol as they left out some of the additives; whether these ' left out' additives actually were useful is a debatable point, as petrol is sort of aimed at the lowest common denominator, your average family saloon (they make up the majority of the market, no snobbery intended).
Nowadays, the supermarket petrol is cheaper due to bulk buying - there are many more supermaket outlets per chain - and the fact that it can be used as a ' loss leader' , to get you into the supermarket itself, where the real money is.
Yes, sympathetic use of the car - gentle when cold, occassional blasts when warm to burn off the sediments in the oil etc. must do more good than fancy petrol.
I still maintain that 95/97 octane must be what car manufacturers build their cars for; there is no Optimax in Europe, after all. Suggesting 98 makes them seem special/high performance/a cut above the ' ordinary' car&driver.
We seem to have forgotten that Porsche has got the name it has due partly to it' s engineering excellence, strength and reliablity (one of the reasons I bought my first) - who else has won the big race 16 times, when the Japanese have only won once ?
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Of course, they sell their cars all over the world. Not every country has the same petrol quality. Most gas stations in the US sell stuff that has the octance number in the 80' s (this is the cheap stuff you put in the rental cars before thrashing them to death).
Other countries, far east, Australasia, middle east, America (north and South) as well as Europe can' t all have the same standards of petrol. However the cars all run there (do they all have to put aftermarket additives in their tanks?)
As regards the supermarkets and their loss leader strategy, this no longer applies. They make money on their petrol (unless they do tokens or similar), since the prices are the same as Esso, Shell, etc. They all operate a price watch scheme and copy each other. I never notice more than 1p difference between any of them.
I also read once that all the petrol was the same, since it all came from the same refineries and is sold in bulk to whoever wants to resell it (much like electricity and gas now is).
Rgds, Stuart.
Other countries, far east, Australasia, middle east, America (north and South) as well as Europe can' t all have the same standards of petrol. However the cars all run there (do they all have to put aftermarket additives in their tanks?)
As regards the supermarkets and their loss leader strategy, this no longer applies. They make money on their petrol (unless they do tokens or similar), since the prices are the same as Esso, Shell, etc. They all operate a price watch scheme and copy each other. I never notice more than 1p difference between any of them.
I also read once that all the petrol was the same, since it all came from the same refineries and is sold in bulk to whoever wants to resell it (much like electricity and gas now is).
Rgds, Stuart.
A few points:
The knock sensor retards the ignition to accomodate lower grade petrol.
(This DOES mean performance is affected - although I agree it might not be possible to tell!) By having the spark plug fire a couple of degrees sooner, you give the mixture more time to burn, thus burning more completely, thus releasing more energy, thus creating more power. One of the limiting factors in how much advance you can use is knock. This is one of the places octane comes into play. Lower octane fuels burn more quickly and limit the amount of advance you can dial in.
Shell made the petrol that killed Vauxhall Cavaliers (!) " Formula Shell" was quickly withdrawn!
Optimax IS available in Germany - and is 99RON not 98 (as in Europe Super Unleaded is 98RON - it is only the UK that has lowered it to 97)
The scale for Petrol octane is different in the USA. 87 in the USA is something like 95 in the UK I believe?
You can' t get Super Unleaded in Italy (spoilsports!)
I also hear that all petrol is the same - it is the additives they bung in at delivery that turns it in to a Shell, Agip, or Sainsbury brand.
The knock sensor retards the ignition to accomodate lower grade petrol.
(This DOES mean performance is affected - although I agree it might not be possible to tell!) By having the spark plug fire a couple of degrees sooner, you give the mixture more time to burn, thus burning more completely, thus releasing more energy, thus creating more power. One of the limiting factors in how much advance you can use is knock. This is one of the places octane comes into play. Lower octane fuels burn more quickly and limit the amount of advance you can dial in.
Shell made the petrol that killed Vauxhall Cavaliers (!) " Formula Shell" was quickly withdrawn!
Optimax IS available in Germany - and is 99RON not 98 (as in Europe Super Unleaded is 98RON - it is only the UK that has lowered it to 97)
The scale for Petrol octane is different in the USA. 87 in the USA is something like 95 in the UK I believe?
You can' t get Super Unleaded in Italy (spoilsports!)
I also hear that all petrol is the same - it is the additives they bung in at delivery that turns it in to a Shell, Agip, or Sainsbury brand.
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I have been using Esso and BP' s regular 95 octane unleaded, as mentioned 3 weeks ago. During this time I have got through about 40 gallons and have not noticed any real difference. It starts the same, ticks over the same, accelerates the same (as far as I can tell) and makes pretty much the same noise.
I haven' t detected any pinking even with my foot on the floor and the throttle response seems the same. The fuel consumption seems the same as well (near enough).
I might try a tankful of the optimax (it requires a bit of a detour to go and get it) to make sure.
In summary though, the sky has not fallen down and as stated in the manual, it runs on 95 without any issues.
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Quite a few of my mates race motorbikes and ride 1000cc roadbikes, and they reckon there is a marked difference between Optimax and other super unleadeds. Apparently more noticeable when they' ve been using Optimax for a while and then put some other brand of fuel in - they notice a drop off in performance!!!
Not really noticed much differnce in my Boxster but I still brim it with Optimax!! Victim of the hype but it has the highest RON, so it must be good - mustn' t it ??!!?? [
]
Cheers
Not really noticed much differnce in my Boxster but I still brim it with Optimax!! Victim of the hype but it has the highest RON, so it must be good - mustn' t it ??!!?? [
]Cheers
OPTIMAX might be the best thing since....er, well the last best thing but I can' t tell the difference in any of my cars. But my wallet can. Are we just victims of good marketing. Surely we wouldn' t fall for it.
I was given a DYSON vacuum cleaner and after all the hype I expected it to remove the pattern from my carpets! It was rubbish, no, worse than that it was RUBBISH. I threw it in a skip in disgust and went back to my Miele vacuum cleaner (German product wins again).
So my GT3 has just had a tank of 107 octane racing fuel. Any difference..NO.
The engine management systems are designed to run on a variety of fuels and unless your engine has been tuned to run on OPTIMAX and nothing less it won' t make a difference. There, I said it and I feel better now. Oh, damn my car seems to be going quicker. Don' t worry its not the OPTIMAX its just the improved power to weight ratio now that my wallet is so much lighter. So OPTIMAX does make your car go faster. Back to square one. [&:]
I was given a DYSON vacuum cleaner and after all the hype I expected it to remove the pattern from my carpets! It was rubbish, no, worse than that it was RUBBISH. I threw it in a skip in disgust and went back to my Miele vacuum cleaner (German product wins again).
So my GT3 has just had a tank of 107 octane racing fuel. Any difference..NO.
The engine management systems are designed to run on a variety of fuels and unless your engine has been tuned to run on OPTIMAX and nothing less it won' t make a difference. There, I said it and I feel better now. Oh, damn my car seems to be going quicker. Don' t worry its not the OPTIMAX its just the improved power to weight ratio now that my wallet is so much lighter. So OPTIMAX does make your car go faster. Back to square one. [&:]
Howard Davis
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I read an artilcle in Car magazine al little while ago. they examined valves and pistons in high performance cars driven with nad without Optimax. The authors were in no doubt of the visible differences ater using Optimax. All looked cleaner after using optimax amd the authors were convinced of the benefits, so am I. Nothing but Optimax goes in my new Boxter S.
Howard
Howard
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I' m a bit baffled by Optimax and the implied improvement in performance. A few years ago, I lived in Switzerland and 98 octane was only 61p per litre so it become my fuel of choice for my 2.5 Vectra GSI (oh the shame of it now ! [&o]). The difference in performance was very noticeable and I got an extra 30 miles range per tankful i.e. 330 miles instead of 300 before hitting the red mark on the gauge.
I feel no difference whatsoever between 95, 97 or 98 octane with the Boxster. What' s going on ?
I feel no difference whatsoever between 95, 97 or 98 octane with the Boxster. What' s going on ?
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I think the key issue lies with the cleanliness of the engine.
Optimax contains detergents to clean the injectors, valve stems, inlet ports, and will also keep the piston crown and combustion chamber cleaner.
If your car does lots of short journeys where it never gets warm, or sits in traffic idling, then you are likely to gradually build up carbon deposits. Switching to optimax would remove these, as has been demonstrated in a number of magazine articles. This then allows the engine to breath easier, you get the correct amount of fuel out of the injectors, and you get a more efficient fuel air mixture leading to more power, or alternatively more mpg for the same response.
I also saw a magazine article where they took a Z3 M roadster, but this had clean valves etc. already and with optimax there was virtually no difference.
If a car is regularly taken for long journeys at motorway speeds, and or driven entusiastically, then the carbon build is very slow with regular petrol.
If the engine is already clean, and the car is designed to work with 95 or 98/97, then I think this is why you notice little difference.
I think optimax is fine if you are unfortunate enough to trundle round London all day, but if you live somewhere a bit more open, then it is not necessary to use it all the time. (Occaisional use may still help, i.e. every 5th or 10th tankful, to keep things clean).
Optimax contains detergents to clean the injectors, valve stems, inlet ports, and will also keep the piston crown and combustion chamber cleaner.
If your car does lots of short journeys where it never gets warm, or sits in traffic idling, then you are likely to gradually build up carbon deposits. Switching to optimax would remove these, as has been demonstrated in a number of magazine articles. This then allows the engine to breath easier, you get the correct amount of fuel out of the injectors, and you get a more efficient fuel air mixture leading to more power, or alternatively more mpg for the same response.
I also saw a magazine article where they took a Z3 M roadster, but this had clean valves etc. already and with optimax there was virtually no difference.
If a car is regularly taken for long journeys at motorway speeds, and or driven entusiastically, then the carbon build is very slow with regular petrol.
If the engine is already clean, and the car is designed to work with 95 or 98/97, then I think this is why you notice little difference.
I think optimax is fine if you are unfortunate enough to trundle round London all day, but if you live somewhere a bit more open, then it is not necessary to use it all the time. (Occaisional use may still help, i.e. every 5th or 10th tankful, to keep things clean).
The benefits of higher octane will be noticed more in some cars than others.
It all depends on wether the car knocks on standard unleaded or not. If it does the knock sensor will retard the ignition which will affect the performance.
If it doesn' t and the ignition map does not try for anymore advance then you won' t get any benefit.
Some cars (e.g. Subaru imprezza turbos) only very slowly advance the ignition again once a knock has been detected, so switching from unleaded to super wouldn' t show immediatly as unless the ECU is reset, there would be a very gradual increase.
I believe however Porsches do not have the Subaru set up and should respond instantly if they are to get benefits.
Generally Engines that run more advance are more efficient so if you are going to get a power advantage you should also see an economy benefit if you don' t then there is probably no point (other than cleaning benefits).
Some cars come from the manufacturers more able to take advantage of higher octane fuels - they have a wider range of self adjustment. ( I believe Vauxhall / opels are good in this respect).
As an example on my 944 Turbo for instance I notice better economy on super unleaded against standard, but no difference between super and optimax. I think that it cannot adjust itself to take advantage of higher octane than say 97, as it has reached the end of it' s self advancing range.
Tony
It all depends on wether the car knocks on standard unleaded or not. If it does the knock sensor will retard the ignition which will affect the performance.
If it doesn' t and the ignition map does not try for anymore advance then you won' t get any benefit.
Some cars (e.g. Subaru imprezza turbos) only very slowly advance the ignition again once a knock has been detected, so switching from unleaded to super wouldn' t show immediatly as unless the ECU is reset, there would be a very gradual increase.
I believe however Porsches do not have the Subaru set up and should respond instantly if they are to get benefits.
Generally Engines that run more advance are more efficient so if you are going to get a power advantage you should also see an economy benefit if you don' t then there is probably no point (other than cleaning benefits).
Some cars come from the manufacturers more able to take advantage of higher octane fuels - they have a wider range of self adjustment. ( I believe Vauxhall / opels are good in this respect).
As an example on my 944 Turbo for instance I notice better economy on super unleaded against standard, but no difference between super and optimax. I think that it cannot adjust itself to take advantage of higher octane than say 97, as it has reached the end of it' s self advancing range.
Tony
I hear Shell have introduced V-Power in Europe and will be introducing it in England soon offering 100 octane fuel!
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