What is the difference between premium and normal unleaded petrol?

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television said:
It really comes down to the requirements of the engine, if it needs it then use it, if you car does not need it then there is nothing to be gained at all in terms of power, and that relates to milaeage
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I guess the next thing to ask is, how do you know if your engine needs it?
 
In the UK regular and Super unleaded are produced to different BS specifications. Have a look at the pumps when you next fill up. Basically, super has extra octane improver added.
You MAY think you notice better performance, but its more likely in the mind. Economy will be slightly improved due to less fuel required for a given speed. As TV says, use whatever is stated in your cars handbook. Modern cars computers senses what the calorific value of the fuel used and constantly adjusts the timing to suit. So, in theory, performance will always remain constant regardless of fuel octane - to a point.
 
I've got a W203 230K which stats super unleaded in the manual yet the dealer said std unleaded would be fine. I posted a similar question a couple of month ago and the general consensious on here was that std unleaded would be fine and not do any damage to the engine. Been using std for 7k miles now and not had a problem. Performance fine and mpg great.
 
There have been several objective tests of high octane fuel; they have shown (using dyno runs) that higher performance engines give more bhp and torque on it but more basic engines don't benefit at all.

On engines that do benefit, if you don't use the extra power then you will get better MPG.

These effects are slight, you would need either a dyno or other controlled conditions to see them. With my V6 Sharan the torque increase on Shell Optimax (and then V-Power) was clearly noticeable when towing. With normal fuel 6th gear could only be used on the flat ... the slightest incline needed a shift down. And on a regular (very) long run on cruise control without the caravan the computer showed better MPG each time I used the Shell fuel.
 
I've always shelled out the extra for "super" if I'm driving something quick - both of my Imprezas (turbocharged) and the C43 were fed exclusively on a diet of Optimax/V-power, or failing that Tesco super unleaded. You don't buy a greyhound and feed it scraps..

The Fiat, on the other hand, eats whatever it's given and doesn't seem to give a toss. I reckon it would run quite happily on paraffin..

Cheers,

Gaz
 
gaz_l said:
I've always shelled out the extra for "super" if I'm driving something quick - both of my Imprezas (turbocharged) and the C43 were fed exclusively on a diet of Optimax/V-power
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Me too, but at 110p/l it's making me wince now!! :crazy:

gaz_l said:
You don't buy a greyhound and feed it scraps.
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Again, me too!! Ours eats better than me, and she's retired!! :mad:
 
i use super+ in the amg as it states it in the handbook and the dealer also said to use nothing less than 98 ron i (think)is it just a fiddle with car manufactures and fuel companies?
 
Bobby Dazzler said:
Me too, but at 110p/l it's making me wince now!! :crazy:
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Another reason I parted with the C43.. I don't think fuel prices are going down any time soon, and once we are all used to £1/litre they will start to rise again. I reckon this time next year we'll be looking at £1.30, maybe even £1.50. I hope i'm wrong, but if not.. you read it here first.

Cheers,

Gaz
 
gaz_l said:
Another reason I parted with the C43.. I don't think fuel prices are going down any time soon, and once we are all used to £1/litre they will start to rise again. I reckon this time next year we'll be looking at £1.30, maybe even £1.50. I hope i'm wrong, but if not.. you read it here first.

Cheers,

Gaz
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hope not:crazy: :crazy:
 
Without any specialist knowledge my reading of independent tests (not PR fantasies without any real numbers attached) suggests you get the full benefit of ultra fuels only if you have a high revving, high specific output motor, preferably turbo-sharged. In other words, if you're pushing engine technology to the limits (for a road car) you benefit from using ultra grade fuels.

Otherwise, you get more economy and performance from a clean, well maintained car with correct tyre pressures, driven efficiently, than from burning ultra fuels.

As far as 98RON goes, the ECU will compensate for fuels down to 91RON so what you put in the tank is down to driver choice and driving style.

IMO!:)
 
Birdman said:
Without any specialist knowledge my reading of independent tests (not PR fantasies without any real numbers attached) suggests you get the full benefit of ultra fuels only if you have a high revving, high specific output motor, preferably turbo-sharged. In other words, if you're pushing engine technology to the limits (for a road car) you benefit from using ultra grade fuels.

Otherwise, you get more economy and performance from a clean, well maintained car with correct tyre pressures, driven efficiently, than from burning ultra fuels.

As far as 98RON goes, the ECU will compensate for fuels down to 91RON so what you put in the tank is down to driver choice and driving style.

IMO!:)
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Thank you Birdman I was reading gl boy post and thinking of where the lower limit was, arbeit with less power, so a very good 95-96 is not that far away:)
 
television said:
Thank you Birdman I was reading gl boy post and thinking of where the lower limit was, arbeit with less power, so a very good 95-96 is not that far away:)
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so would you say i could save 10p a litre by putting normal unleaded in without damaging my engine?but would the warranty still be void if i did?:confused: regards jon
 
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