Superunleaded?
23 November 2004, 11:28 PM
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Superunleaded?
We've only just found out that it is best to run the scooby on super unleaded!
We were talking to some lads from Barnsley who said that the price of it is 92ppl (ouch!)
.
Our local Sainsbury's is only 84ppl - is this a good price???
We were talking to some lads from Barnsley who said that the price of it is 92ppl (ouch!)
.Our local Sainsbury's is only 84ppl - is this a good price???
23 November 2004, 11:31 PM
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Not bad for 97 RON.
Have you checked out the price of Shell Optimax in your area?
Incidentally, what model are you running?
Have you checked out the price of Shell Optimax in your area?
Incidentally, what model are you running?
23 November 2004, 11:35 PM
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Originally Posted by Harry_Boy
Not bad for 97 RON.
Have you checked out the price of Shell Optimax in your area?
Incidentally, what model are you running?
Have you checked out the price of Shell Optimax in your area?
Incidentally, what model are you running?
Scoobs is an 02 WRX.
23 November 2004, 11:41 PM
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Optimax is 98.6 RON (ie octane), compared to super unleaded at 97 RON. So, as such, it's 'better' - more "energy" as such.
But, Optimax used a normal unleaded (95 RON) base, with additives to bring it up to a higher figure, while proper SUL uses a more 'refined' base. There have been reports of Optimax 'going off' when lying unused in the tank (either the petrol station's or the car's). This can cause pinking and hence force the car's ECU to retard the ignition to stop pre-detonation.
My CEL (Check Engine Light) occasionally comes on with Optimax, but never with SUL. Could be coincidence, but my thought is that you can sometimes get a dodgy batch, while conventional SUL may be a slightly lower octane, but is more stable....
Hope that makes sense!
But, Optimax used a normal unleaded (95 RON) base, with additives to bring it up to a higher figure, while proper SUL uses a more 'refined' base. There have been reports of Optimax 'going off' when lying unused in the tank (either the petrol station's or the car's). This can cause pinking and hence force the car's ECU to retard the ignition to stop pre-detonation.
My CEL (Check Engine Light) occasionally comes on with Optimax, but never with SUL. Could be coincidence, but my thought is that you can sometimes get a dodgy batch, while conventional SUL may be a slightly lower octane, but is more stable....
Hope that makes sense!
24 November 2004, 01:31 AM
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I hear conflicting stories about this.
One is that Optimax uses octane boosters which have a short shelf life so it's a waste of money unless bought in Merseyside or Cheshire
The other is that all petrol has a RON of about 65 and various addiditives are used to raise it to 95, 97, 98.5 or whatever.
I've not been able to get a definitive answer
One is that Optimax uses octane boosters which have a short shelf life so it's a waste of money unless bought in Merseyside or Cheshire
The other is that all petrol has a RON of about 65 and various addiditives are used to raise it to 95, 97, 98.5 or whatever.
I've not been able to get a definitive answer
24 November 2004, 01:50 AM
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Nearest Optimax emporium to Dewsbury would be M1 Jcn 40 and head towards Wakey for a couple of hundred yards - 88.9p/litre
Others in the area at Three Nuns and Bruntcliffe but this could be a tad out of your way unless you're in the Morley area anytime...
Lum, it seems from previous threads that optimax is "normal" fuel with some "jungle juice"
added in at some point. This additional bit might be the bit that degrades or evaporates quickly (is optimax more volatile?) and hence this angel's share disappears more quickly, therefore a shorter shelf-life - just my 2p 
PS just read H-B's post and I'm not editing this one so there...
PPS my CEL has never come on with optimax or super but then I don't drive like H-B
Others in the area at Three Nuns and Bruntcliffe but this could be a tad out of your way unless you're in the Morley area anytime...
Lum, it seems from previous threads that optimax is "normal" fuel with some "jungle juice"
added in at some point. This additional bit might be the bit that degrades or evaporates quickly (is optimax more volatile?) and hence this angel's share disappears more quickly, therefore a shorter shelf-life - just my 2p PS just read H-B's post and I'm not editing this one so there...
PPS my CEL has never come on with optimax or super but then I don't drive like H-B
24 November 2004, 03:08 AM
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remember formula shell in the mid eighties ?? , well i fell for that one , used to go miles outta my way to fill up , looking back now i dont think the rs1600i or the xr2 went any better , knew a few volvo340's that didnt like it though
nearly all fuel you buy in the north comes from shell at the stanlow refinery , esso at trafford park manchester (which is piped up from the south coast refinery )or lindsey oil refinery at immingham
this includeds all supermarket fuel
although optimax will be exclusive to shell as it will be the additive they will have formulated and added at the refinery
i also know some of the tricks the tankers drivers get up to while delivering the stuff , whoops said to much already
nearly all fuel you buy in the north comes from shell at the stanlow refinery , esso at trafford park manchester (which is piped up from the south coast refinery )or lindsey oil refinery at immingham
this includeds all supermarket fuel
although optimax will be exclusive to shell as it will be the additive they will have formulated and added at the refinery
i also know some of the tricks the tankers drivers get up to while delivering the stuff , whoops said to much already
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24 November 2004, 03:43 AM
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Apple, IIRC the higher the octane, the less volatile it is. The theory is (I think) that making extremely volatile fuel is easy, but being able to control the ignition to the specific spark point within a very hot engine is where the chemistry comes in. The power comes from the fuel working better with the engines finely balanced timing. If it's too volatile, you'll get pinking where the fuel ignites early before the valves are closed, set off by the heat of the engine. AFAIK there isn't any modern petrols which won't ignite at spark point, unless there is a fault on the car, so you can go as high a RON as you like within reason. I seem to remember Dazza running some 106 RON at Elvington last year
24 November 2004, 08:53 AM
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Dave, taken from www.truckpulls.com
"6.12 How do other fuel properties affect octane?
Several other properties affect knock. The most significant determinant of octane is the chemical structure of the hydrocarbons and their response to the addition of octane enhancing additives. Other factors include:- Front End Volatility - Paraffins are the major component in gasoline, and the octane number decreases with increasing chain length or ring size, but increases with chain branching. Overall, the effect is a significant reduction in octane if front end volatility is lost, as can happen with improper or long term storage. Fuel economy on short trips can be improved by using a more volatile fuel, at the risk of carburettor icing and increased evaporative emissions. Final Boiling Point.- Decreases in the final boiling point increase fuel octane. Aviation gasolines have much lower final boiling points than automotive gasolines. Note that final boiling points are being reduced because the higher boiling fractions are responsible for disproportionate quantities of pollutants and toxins. Preignition tendency - both knock and preignition can induce each other."
"6.12 How do other fuel properties affect octane?
Several other properties affect knock. The most significant determinant of octane is the chemical structure of the hydrocarbons and their response to the addition of octane enhancing additives. Other factors include:- Front End Volatility - Paraffins are the major component in gasoline, and the octane number decreases with increasing chain length or ring size, but increases with chain branching. Overall, the effect is a significant reduction in octane if front end volatility is lost, as can happen with improper or long term storage. Fuel economy on short trips can be improved by using a more volatile fuel, at the risk of carburettor icing and increased evaporative emissions. Final Boiling Point.- Decreases in the final boiling point increase fuel octane. Aviation gasolines have much lower final boiling points than automotive gasolines. Note that final boiling points are being reduced because the higher boiling fractions are responsible for disproportionate quantities of pollutants and toxins. Preignition tendency - both knock and preignition can induce each other."
24 November 2004, 09:46 AM
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Originally Posted by Apple
PPS my CEL has never come on with optimax or super but then I don't drive like H-B
24 November 2004, 11:51 AM
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Originally Posted by Apple
Dave, taken from www.truckpulls.com
"6.12 How do other fuel properties affect octane?
Several other properties affect knock. The most significant determinant of octane is the chemical structure of the hydrocarbons and their response to the addition of octane enhancing additives. Other factors include:- Front End Volatility - Paraffins are the major component in gasoline, and the octane number decreases with increasing chain length or ring size, but increases with chain branching. Overall, the effect is a significant reduction in octane if front end volatility is lost, as can happen with improper or long term storage. Fuel economy on short trips can be improved by using a more volatile fuel, at the risk of carburettor icing and increased evaporative emissions. Final Boiling Point.- Decreases in the final boiling point increase fuel octane. Aviation gasolines have much lower final boiling points than automotive gasolines. Note that final boiling points are being reduced because the higher boiling fractions are responsible for disproportionate quantities of pollutants and toxins. Preignition tendency - both knock and preignition can induce each other."
"6.12 How do other fuel properties affect octane?
Several other properties affect knock. The most significant determinant of octane is the chemical structure of the hydrocarbons and their response to the addition of octane enhancing additives. Other factors include:- Front End Volatility - Paraffins are the major component in gasoline, and the octane number decreases with increasing chain length or ring size, but increases with chain branching. Overall, the effect is a significant reduction in octane if front end volatility is lost, as can happen with improper or long term storage. Fuel economy on short trips can be improved by using a more volatile fuel, at the risk of carburettor icing and increased evaporative emissions. Final Boiling Point.- Decreases in the final boiling point increase fuel octane. Aviation gasolines have much lower final boiling points than automotive gasolines. Note that final boiling points are being reduced because the higher boiling fractions are responsible for disproportionate quantities of pollutants and toxins. Preignition tendency - both knock and preignition can induce each other."
A bit like most aviation fuel that Andy. Well over my head
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