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Well the time has come after 2500miles that I have a 200 mile round trip planned and I may have to fill up with petrol.....a sorry day lol

But what petrol is best to use, I have seen that super unleaded is preferred and I don't think will use supermarket fuel, so what does everyone think??
 

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Shell optimax if you havn't run it much. Cleared carbon out of our MR2 including Turbo and it went like sh!t off a stick. We got 6% better mileage too. Be interesting to hear how it works on an Atkins cycle engine. Congrats too by the way:).
 

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I just use the ordinary supermarket unleaded. Why waste money on anything more when that is the grade the manual specifies.
 

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Bog standard fuel of the correct RON with no additional additives, the additives will go "off" quicker in premium fuel - its not really an issue if your going to use the whole tank but you don't really want to leave it in for long periods.

Also I believe the US have a second problem that their high octane fuel has ethanol in, so that goes off really quick if not used.
 

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US fuel is different. I definitely recommend Shell Optimax or BP Super unleaded; the ICE runs more smoothly and quietly with super unleaded and Optimax in particular is great at keeping the engine clean. I've done various tests on cars from a Subaru Impreza to a Jaguar XKR and in every single case Optimax has been best, quietest, smoothest and slightly improved economy.
Avoid supermarket fuels, particularly as the engine isn't used all that often. Yes, it meets the minimum spec in the manual, but so does a Matsui TV from Dixons and I bet you have a proper brand TV at home :) You get what you pay for, simple.
 
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Or in my case, at a well known supermarket, you might pay for what you don't get when the pump shows a figure 10% greater than the size of the tank.
Ouch! :(
 

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I think that 'premium' petrol is recommended because it may sit in your tank for 6 months albeit vacuum packed.
When I know I will be using it all in one trip I put 'ordinary' in and then top up to a 1/3rd with the best when I get back. Worked for me getting on 2.5 yrs now and 20K miles.
 

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Or in my case, at a well known supermarket, you might pay for what you don't get when the pump shows a figure 10% greater than the size of the tank.
That happened to me once. I spoke to Trading Standards who were there within the hour and tested the pump into their calibrated tanks. The pump was perfect!
 

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Sad day today. I had to fill up with Petrol!! First time since December 12th! Did 2207 miles on 6.5 gallons which works out at 339.53 MPG!!!!:p
Filled up with ESSO Super. Be interesting to see if it makes any difference as we are driving to Wales next week.
 

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I researched fuel types and decided that Shell Nitro+ was the appropriate fuel.

The reasons are that it contains approximately 5% additional calorific value, and as it is being converted directly to energy (rather than just 'turning the engine over' and generating heat) then you should get the benefit of that additional energy content.

The other reason is that the data I have obtained show it has a 'maximum' of 5% ethanol ('0 to 5%') and 'trace' methanol. The only other 99 RON fuel, Tesco Momentum, has 5% ethanol and 3% methanol, which is why it has a high octane rating. These components reduce the calorific value of the fuel compared with regular fuel, rather than increasing it in the Nitro+ recipe.

The thing about ethanol and methanol is that they will act as oxidising agents and will react with the metals in your fuel system. Of course, the materials will have been chosen to be as unreactive as possible in the presence of these alcohols, but there will be some reaction. Maybe it is so small as to never make any difference at all, and I suspect that is probably the case, but this stuff may sit in your tank for months.

I'll add I have no great experience to yet go on. Only used 10 litres so far.
 

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I really don't notice the difference with High octane fuels.
As I have used about 200 gallons over the last 22000 miles, I think I should have noticed a difference.....
I guess that if you work the engine hard all the while then maybe the difference is more noticeable, but my engine typically sits in either the lowest, or second Rev setting.
The only time that it goes higher is if it finds a hill, or I stand on the loud pedal....
 

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I researched fuel types and decided that Shell Nitro+ was the appropriate fuel.

The reasons are that it contains approximately 5% additional calorific value, and as it is being converted directly to energy (rather than just 'turning the engine over' and generating heat) then you should get the benefit of that additional energy content.

The other reason is that the data I have obtained show it has a 'maximum' of 5% ethanol ('0 to 5%') and 'trace' methanol. The only other 99 RON fuel, Tesco Momentum, has 5% ethanol and 3% methanol, which is why it has a high octane rating. These components reduce the calorific value of the fuel compared with regular fuel, rather than increasing it in the Nitro+ recipe.

The thing about ethanol and methanol is that they will act as oxidising agents and will react with the metals in your fuel system. Of course, the materials will have been chosen to be as unreactive as possible in the presence of these alcohols, but there will be some reaction. Maybe it is so small as to never make any difference at all, and I suspect that is probably the case, but this stuff may sit in your tank for months.

I'll add I have no great experience to yet go on. Only used 10 litres so far.
I bought a new rotavator a few weekends back and the shop tried to sell me special petrol at £20 a gallon. He had a jar with packing bubbles floating in it and another with normal petrol that he then desolved the same bubbles in. I got a long leacture on how bad modern petrol is if left in the engine for any length of time it kills all the gaskets.
 

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I found Super unleaded helps keep a rarely used engine running sweeter or should I say an engine that does low mileages, otherwise any old petrol will do if you hammer it up and down the motorway all day.
 

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I'm not convinced on 99 RON for the Ampera.

Being normally aspirated, non GDI, and overall a fairly basic engine, I'd not expect it to have that many sensors or a super advanced ECU to adjust on the fly, if so the fuel probably matter little in terms of power output.

I'd say in an application where you are infrequently running the ICE, because all modern petrol "goes off", maybe finding one that has a better shelf life would be better than one with a higher octane.
 

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..Being normally aspirated, non GDI, and overall a fairly basic engine...
Apparently not. I have read they run significantly altered valve opening timings to simulate an over-expansion (Atkinson-like) engine, and then push the ignition to compensate.

This is why they say 'premium gas only' in the US, because it'll suffer pre-ignition badly if it tried this with low RON.
 
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