Esso Super Unleaded change.
Discussion
HJG said:
As for all the comments about 95 vs 99 and so on, higher octane fuel allows more spark advance (igniting the mixture earlier). This results in a more efficient burn, meaning more torque and improved specific fuel consumption. Note the word specific....i.e. fuel burnt for a given power output.
Some engines are designed to operate on higher octane fuel, typically high compression or high performance and/or tuned boosted engines. If there is no knock sensor and you are forced to run 95, one may have to retard the timing slightly. On a car of such vintage, it can be usually done by rotating the distributor a few degrees.
Cars equipped with a knock sensor can 'detect' lower octane fuel by detonation of the fuel in the combustion chamber. It then tells the ECU to retard the timing. The ECU will naturally keep trying to advance it again until the knock sensor gives the signal once more...and so it goes on.
Spot on explanation. The higher the octane, the more you can compress the fuel before it self-detonates, hence you can get a bigger bang from it.Some engines are designed to operate on higher octane fuel, typically high compression or high performance and/or tuned boosted engines. If there is no knock sensor and you are forced to run 95, one may have to retard the timing slightly. On a car of such vintage, it can be usually done by rotating the distributor a few degrees.
Cars equipped with a knock sensor can 'detect' lower octane fuel by detonation of the fuel in the combustion chamber. It then tells the ECU to retard the timing. The ECU will naturally keep trying to advance it again until the knock sensor gives the signal once more...and so it goes on.
I'm in the same situation as many in here. The sticker inside my fuel cap says 95 and 98 and the manual says either can be used, but since it's a performance car I assume you get maximum performance by running 98 and after seeing a few dyno runs from stock and tuned examples running 95 and 98 this is definitely the case. Always Tesco Momentum for me since it's by far the cheapest out of all the high octane fuels and I get clubcard points from it (when the bloody scanner on the pumps work).
Evanivitch said:
ninepoint2 said:
Sorry if this is a stupid question, but it seems that Ethanol is not good, why is that?
It depends. Firstly, in older cars it can harm the fuel delivery system.Also, it has a lower calorific value. So it can artificially boost RON numbers, you should get more power because the engine adapts positively to the higher RON, but a pure ethanol fuel actually contains less energy.
It's only going to improve your peak power output. Which I suspect unless you're a joyrider you won't touch very often day to day. And it's not goi to improve efficiency enough to recoup >7p per litre price disadvantage.
I do need 99 octane for my GT86 map which is optimized for that fuel and driven with a laptop plugged in to tweak it I'm real world conditions to the absolute optimum.
I can switch maps at the press of a button to a 95 Ron map and I have tried it out of curiosity on a quarter tank of regular. It made no difference in day to day driving.
I do need 99 octane for my GT86 map which is optimized for that fuel and driven with a laptop plugged in to tweak it I'm real world conditions to the absolute optimum.
I can switch maps at the press of a button to a 95 Ron map and I have tried it out of curiosity on a quarter tank of regular. It made no difference in day to day driving.
baptistsan said:
f
k me! 139.9ppl in Bury St Edmunds 
10ppl more expensive than Shell's finest. I've stuck some in the Saab & will see how it goes. This won't be a regular habit at that price
I had another look on my receipt and that's what I paid too! 10p more than V Power for the promise of 'Stella Artois for your car'. k me! 139.9ppl in Bury St Edmunds 10ppl more expensive than Shell's finest. I've stuck some in the Saab & will see how it goes. This won't be a regular habit at that price
Haltamer said:
Car_Nut said:
Thank you everyone for an incredibly useful and interesting thread.
I'm honestly not sure if that is sarcasm 
With two classic cars running high compression engines, and one of them old fuel lines, it is incredibly useful.
Car_Nut said:
Of course it isn’t. What is wrong with some people?
With two classic cars running high compression engines, and one of them old fuel lines, it is incredibly useful.
It is quite interesting and useful, but you never know with some people on PH :PWith two classic cars running high compression engines, and one of them old fuel lines, it is incredibly useful.
I checked the local Esso at the end of my road and the pump labels are still for 97, Which is odd given it's a rather popular station.
I assume they're allowing the tanks to be drained "naturally" prior to 99 switchover? Would've expected it to happen by now though.
Haltamer said:
It is quite interesting and useful, but you never know with some people on PH :P
I checked the local Esso at the end of my road and the pump labels are still for 97, Which is odd given it's a rather popular station.
I assume they're allowing the tanks to be drained "naturally" prior to 99 switchover? Would've expected it to happen by now though.
Yes, they are allowing their tanks to get to a level where they can add the 99 Ron - then you will see new branding on the pumps. I checked the local Esso at the end of my road and the pump labels are still for 97, Which is odd given it's a rather popular station.
I assume they're allowing the tanks to be drained "naturally" prior to 99 switchover? Would've expected it to happen by now though.
Most places I deliver to have got to that point, but it depends what was in the tank and how much the 97 was selling.
I deliver to Sainsburys, Costco and Co-op petrol filling stations too - their Super Unleaded are all 99 Ron too (I don’t know why Sainsburys market it as 98, as we 100% lift 99 Ron from the terminals).
W88CHY said:
Yes, they are allowing their tanks to get to a level where they can add the 99 Ron - then you will see new branding on the pumps.
Most places I deliver to have got to that point, but it depends what was in the tank and how much the 97 was selling.
I deliver to Sainsburys, Costco and Co-op petrol filling stations too - their Super Unleaded are all 99 Ron too (I don’t know why Sainsburys market it as 98, as we 100% lift 99 Ron from the terminals).
Are you delivering exactly the same fuel to Esso, Sainsbury, Costco etc?Most places I deliver to have got to that point, but it depends what was in the tank and how much the 97 was selling.
I deliver to Sainsburys, Costco and Co-op petrol filling stations too - their Super Unleaded are all 99 Ron too (I don’t know why Sainsburys market it as 98, as we 100% lift 99 Ron from the terminals).
W88CHY said:
I deliver to Sainsburys, Costco and Co-op petrol filling stations too - their Super Unleaded are all 99 Ron too (I don’t know why Sainsburys market it as 98, as we 100% lift 99 Ron from the terminals).
That is something of a revelation - I've been peeved at Costco since they stopped offering 99RON a couple of years ago and switched to 97 - There was a thread about it somewhere.If they're selling 99 That would be very handy, but I'd have expected them to advertise it!
Out of interest, where is your delivery? - My local Costco is Thurrock / Lakeside.
cornershop said:
Are you delivering exactly the same fuel to Esso, Sainsbury, Costco etc?
Same fuel to Co-op, Costco and Sainsburys (no further additives added at the terminal) - Esso fuel is additised as it’s loaded onto the tanker (at the terminal side - it’s a bit like telling a computer what customer we are loading for, quantities and grade). Costco put their own additive in when we are delivering it (it’s a control panel, their staff input the amount going into a tank and it calculates the additive and injects it as the fuel flows into the tank).
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