Super unleaded - is it worth the extra cost?
Discussion
Sour Kraut said:
retrorider said:
100 will be in the U.K at some point to confuse the issue even more...
The on-site fuel station at Snetterton sells 100 (probably at other tracks too)I wonder how older cars like my E36 track car would 'manage' a higher octane? Or would it be a worthless exercise?
Chris71 said:
There are two seperate issues here.
One is the octance rating itself. If you have a car calibrated specifically for 98 RON then you risk seriously damaging it by detonation (or 'pinking') if you run it on lesser fuels. Similarly an increasing number of cars have knock sensors, which should be safe to run on 95 RON or below, but won't perform as well as they could.
Second is the various additives in the fuel. The high performance fuels have all sorts of additional components which enhance the long- and short-term health of the engine. Their effect is harder to quantify, but they are there for reason, they're not just marketing gimmicks.
This is what I thought from reading up on it.One is the octance rating itself. If you have a car calibrated specifically for 98 RON then you risk seriously damaging it by detonation (or 'pinking') if you run it on lesser fuels. Similarly an increasing number of cars have knock sensors, which should be safe to run on 95 RON or below, but won't perform as well as they could.
Second is the various additives in the fuel. The high performance fuels have all sorts of additional components which enhance the long- and short-term health of the engine. Their effect is harder to quantify, but they are there for reason, they're not just marketing gimmicks.
Bog standard 95 usually has no info regarding additives/detergent packs etc but these are very much advertised with higher octane fuels.
I'm no expert but as far as I can see, bog standard 95 at Tesco is cheap crap whilst high octane not only provides more bang but helps to maintain everything downstream of the fuel tank.
In the past I've tried both in my cars and can definitely tell that my engines run smoother/cleaner with 99 RON. I can't tell that there's any more power but my EP3 as more economical with Shell Optimax. Now that my MR2 has done over 80k then I use Tesco 99 every tank or so to keep everything clean.
AJB said:
funkyrobot said:
Right, just checked my handbook. For the turbocharged L3 engine (which I think is the Mazda 3 MPS one) they recommend 98 ron. You can use 95 ron in these cars though according to the book.
My 2.0i Sport model seems to fall under the 'every other petrol engine' section which is below the turbo engine section. This simply says '95 ron or above'. Therefore, i'm guessing 95 is fine but I can use higher octanes if desired?
Exactly right. So the turbocharged one is optimised for 98 ron. It can cope with 95 but only by reducing economy and power in the process, so probably not saving any money overall and definitely losing performance.My 2.0i Sport model seems to fall under the 'every other petrol engine' section which is below the turbo engine section. This simply says '95 ron or above'. Therefore, i'm guessing 95 is fine but I can use higher octanes if desired?
Yours is optimised for 95 ron. Using 98 might very slightly increase power/economy (if it's got a knock sensor) - but only very slightly, and not certainly not justifying the extra cost of the fuel on financial grounds. Or using 98 might very slightly reduce power/economy (because the 98 ron fuel has got slightly less energy in it).
For either engine, you won't do any harm at all by using higher ron fuel than specified (other than to your wallet).
I think i'll take a look at putting in a tank of super every now and again to try and make use of the cleaning additives. I'll also run a tank of it to see if it does make any difference
Edited by funkyrobot on Wednesday 22 December 09:03
Doniger said:
Sour Kraut said:
retrorider said:
100 will be in the U.K at some point to confuse the issue even more...
The on-site fuel station at Snetterton sells 100 (probably at other tracks too)I wonder how older cars like my E36 track car would 'manage' a higher octane? Or would it be a worthless exercise?
funkyrobot said:
AJB said:
funkyrobot said:
Right, just checked my handbook. For the turbocharged L3 engine (which I think is the Mazda 3 MPS one) they recommend 98 ron. You can use 95 ron in these cars though according to the book.
My 2.0i Sport model seems to fall under the 'every other petrol engine' section which is below the turbo engine section. This simply says '95 ron or above'. Therefore, i'm guessing 95 is fine but I can use higher octanes if desired?
Exactly right. So the turbocharged one is optimised for 98 ron. It can cope with 95 but only by reducing economy and power in the process, so probably not saving any money overall and definitely losing performance.My 2.0i Sport model seems to fall under the 'every other petrol engine' section which is below the turbo engine section. This simply says '95 ron or above'. Therefore, i'm guessing 95 is fine but I can use higher octanes if desired?
Yours is optimised for 95 ron. Using 98 might very slightly increase power/economy (if it's got a knock sensor) - but only very slightly, and not certainly not justifying the extra cost of the fuel on financial grounds. Or using 98 might very slightly reduce power/economy (because the 98 ron fuel has got slightly less energy in it).
For either engine, you won't do any harm at all by using higher ron fuel than specified (other than to your wallet).
I think i'll take a look at putting in a tank of super every now and again to try and make use of the cleaning additives. I'll also run a tank of it to see if it does make any difference
Edited by funkyrobot on Wednesday 22 December 09:03
DJC said:
It rarely makes any difference whatsoever no matter how high performance the vehicle.
Absolute rubbish.....believe you me my RS4 runs like a bag of bones..especially on tickover..when ive been caught short and had to put in 95...Its quicker more responsive and smoother on 99...What Audi tells us it has to be ran on.The important thing to remember is that the RON rating is a direct indication of the specific heat capacity of the fuel, or in laymans terms, resistance to detonation.
For 95% of cars, running 95 Ron is perfectly adequate, as that is what the engine has been designed to run on, but more importantly, what the ECU has been mapped against.
The ignition will generally be run advanced as possible, without pinking (pre-ignition) leaving a small saftey margin for poor quality fuel. On most engines this is fine, and they can cope with poor fuels below 95 Ron even at max rpm/load.
The problems start on tuned N/A engines or high performance turbocharged engines when you increase the compression ratio, or run high boost, which has a similar effect. The ignition advance is now a LOT more critical, as is the correct grade of fuel. Most high performance engines require 98 Ron or higher ( think first gen impreza, cosworths, Evos & most Jap imports) as that is what the engine has been designed around, & the ECU mapped to.
Now, on an engine running 98 Ron fuel, using 95 Ron won't be a problem for the majority of the time, you may feel a slightly less responsive throttle, and maybe marginally (barely perceptable) rougher running.
The problems start when 95 Ron fuel is run in an engine designed & MAPPED for 98 Ron fuel. At high loading &/or high RPM, during the compression stroke, the fuel/air mixture will get so hot it will either: ignite before the spark plug fires (pre-ignition) due to a hotspot in the engine ( valve edge, glowing incorrect heat rating spark plug, carbon deposit etc etc) acting as an ignition source. This can cause engine damage quickly, and depending on the severity of the pre-ignition, can melt pistons, burn valves and blow tips off spark plugs.
The most dangerous condition of using the incorrect fuel is detonation. This usually occurs on high performance turbocharged engines. This is where the fuel/air mixture gets so hot during the compression stroke, that the charge spontaniously ignites from it's own heat ( we all know compressing somthing creates heat), and unlike pre-ignition, where the burn cycle is completed as normal, just early, detonation causes an explosion rarther than a controlled burn. This can cause almost instant engine failure, bending conrods, to the point they will exit the block, hole pistons & melt spark plugs.
The short answer is running 98/99 Ron fuel in your average car will make zero difference, if the ECU is not mapped for it, it will NOT make any more power or torque, simply because the ignition advance is not increased to make use of the extra heat capacity availiable.
Using 95 Ron or a lower Ron rating than required on say a 98 Ron Mapped engine can range from no perceptable difference to total engine failure.
The other point to consider is most vehicles with a knock sensor can only remove ignition advance, so they will not self-tune to use the extra power.
A good example of incorrect fuel grades killing engines is the early jap import impreza, lots of these suffered melted pistons due to using 95 or even 98 Ron fuel, as the Japs have 99 and even 100+ Ron fuels on the forecourt.
For 95% of cars, running 95 Ron is perfectly adequate, as that is what the engine has been designed to run on, but more importantly, what the ECU has been mapped against.
The ignition will generally be run advanced as possible, without pinking (pre-ignition) leaving a small saftey margin for poor quality fuel. On most engines this is fine, and they can cope with poor fuels below 95 Ron even at max rpm/load.
The problems start on tuned N/A engines or high performance turbocharged engines when you increase the compression ratio, or run high boost, which has a similar effect. The ignition advance is now a LOT more critical, as is the correct grade of fuel. Most high performance engines require 98 Ron or higher ( think first gen impreza, cosworths, Evos & most Jap imports) as that is what the engine has been designed around, & the ECU mapped to.
Now, on an engine running 98 Ron fuel, using 95 Ron won't be a problem for the majority of the time, you may feel a slightly less responsive throttle, and maybe marginally (barely perceptable) rougher running.
The problems start when 95 Ron fuel is run in an engine designed & MAPPED for 98 Ron fuel. At high loading &/or high RPM, during the compression stroke, the fuel/air mixture will get so hot it will either: ignite before the spark plug fires (pre-ignition) due to a hotspot in the engine ( valve edge, glowing incorrect heat rating spark plug, carbon deposit etc etc) acting as an ignition source. This can cause engine damage quickly, and depending on the severity of the pre-ignition, can melt pistons, burn valves and blow tips off spark plugs.
The most dangerous condition of using the incorrect fuel is detonation. This usually occurs on high performance turbocharged engines. This is where the fuel/air mixture gets so hot during the compression stroke, that the charge spontaniously ignites from it's own heat ( we all know compressing somthing creates heat), and unlike pre-ignition, where the burn cycle is completed as normal, just early, detonation causes an explosion rarther than a controlled burn. This can cause almost instant engine failure, bending conrods, to the point they will exit the block, hole pistons & melt spark plugs.
The short answer is running 98/99 Ron fuel in your average car will make zero difference, if the ECU is not mapped for it, it will NOT make any more power or torque, simply because the ignition advance is not increased to make use of the extra heat capacity availiable.
Using 95 Ron or a lower Ron rating than required on say a 98 Ron Mapped engine can range from no perceptable difference to total engine failure.
The other point to consider is most vehicles with a knock sensor can only remove ignition advance, so they will not self-tune to use the extra power.
A good example of incorrect fuel grades killing engines is the early jap import impreza, lots of these suffered melted pistons due to using 95 or even 98 Ron fuel, as the Japs have 99 and even 100+ Ron fuels on the forecourt.
Well that covers it, perfect.
Only ever noticed the difference with higher octane twice.
1. In a jap import engine installed into my MR2 Mk1 after the original destroyed itself.
2. Turbo 207 RC mapped to RON98 in the desert using dodgy lower octane fuel (probably lowe than 95). Economy and performance were appalling.
Only ever noticed the difference with higher octane twice.
1. In a jap import engine installed into my MR2 Mk1 after the original destroyed itself.
2. Turbo 207 RC mapped to RON98 in the desert using dodgy lower octane fuel (probably lowe than 95). Economy and performance were appalling.
Then you lot must drive an awful lot differently to me.
In everything from an Mx5, MG, Integrale, Griff and Sag Ive never found *any* difference during my normal driving whether I used 95 or Optimaxy type stuff.
Mpg stayed roughly the same, performance stayed roughly the same. Reliability stayed the same.
And *my* S6 was still strong after 20k and as everyone in the entire possible world knows, that is the most fragile and dodgy engine in the world ever!
In everything from an Mx5, MG, Integrale, Griff and Sag Ive never found *any* difference during my normal driving whether I used 95 or Optimaxy type stuff.
Mpg stayed roughly the same, performance stayed roughly the same. Reliability stayed the same.
And *my* S6 was still strong after 20k and as everyone in the entire possible world knows, that is the most fragile and dodgy engine in the world ever!
I always use Shell V Power in my M3 Evo as it states use 98 Ron. I won't even use BP Ultimate as it's only 97. About 5 years ago now my friend at work had a 2001 e46 M3 and used to always fill up with 95 Ron and I remember he had massive engine problems and BMW said it was because he was using 95 Ron.
Edited by htid on Friday 24th December 11:13
k all difference (which was what i was expecting anyway)-in fact MPG slightly DROPPED!
DJC said:
Then you lot must drive an awful lot differently to me.
In everything from an Mx5, MG, Integrale, Griff and Sag Ive never found *any* difference during my normal driving whether I used 95 or Optimaxy type stuff.
None of those cars have knock sensors do they? and only one is turbo charged.In everything from an Mx5, MG, Integrale, Griff and Sag Ive never found *any* difference during my normal driving whether I used 95 or Optimaxy type stuff.
The Audi may need more than just a tank of SUL before the engine has adjusted for the better fuel quality.
Try running a Jap Impreza on 95 ron and see how long the engine lasts before knocking itself to death.
Edited by anonymous-user on Monday 3rd January 22:01
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