Hi,
I was wondering if any of you guys have tried, seen or have opinion on the latest performance GAS... from Shell - Australia.

Should I use; 100 octane ... "Shell-Optimax-Extreme".
I mean... is the ethanol additive - safe and OK to use in the Crossfire?
Cost is AUD $1.25 /Litre.

http://www.shell.com/home/Framework?...r_extreme.html

OR

Should I use; 98 octane... "Shell-Optimax".

http://www.shell.com/home/Framework?...t_ga_1602.html

Cost is AUD $1.15 /Litre.

OR

Should I use; 95 octane... "Shell-Premium Unleaded".

http://www.shell.com/home/Framework?...pulp_0323.html

Cost is AUD $1.05 /Litre.

All help much appreciated...

 

Wow, 95 octane and 98...100!!! Can't buy that up here in the states (at the pump, anyway).
I would think 95 would be fine since all that's required (according to the manual, US version is 93)
but if I had that choice, I would try them all and take notes on performance.

 

I seem to have read somewhere on this site -that someone (chemist) was deprecating the use of Ethanol...?

 

Here in the USA we pretty much have no choice on Ethanol additives in gas. The grades offered here pretty much all do 10% Ethanol as a component, with the exception of some racing fuels.

Are the Octane ratings you have posted (R+M)/2 ?

 

unless the engine was designed to take advantage of a higher octane gas, there's really no benefit. a higher octane gas will not burn hotter or longer than 'normal' gas. as long as you're not detonating, the gasoline you use today is working just fine; you won't get any more performance out of higher octane fuel. if you compress the air or raise the temperature in the chamber, higher and higher octane fuels become necessary.

short answer... 95 octane.

 

I'm sorry to expose my ignorance of your terms...?
I've no idea what (R+M)/2 means - unless you defime values for R & M...
(did you see anything about this in the URL's)

PS> The 95 octane URL has a data sheet (PDF) and refers to RON...?

 

Agreed. We've been through this so many times now, it's beginning to sound like a broken record.

 

Hey Juddz,
Sorry to have wasted the 10 secs... of your precious time!
(you didn't have to read it - you know)

 

The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel through a specific test engine with a variable compression ratio under controlled conditions, and comparing these results with those for mixtures of isooctane and n-heptane.

There is another type of octane rating, called Motor Octane Number (MON), which is a better measure of how the fuel behaves when under load. MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally fuel specifications require both a minimum RON and a minimum MON.

In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "normal" gasoline in the US and Canada, would be 91 in Europe.

It is possible for a fuel to have a RON greater than 100, because isooctane is not the most knock-resistant substance available. Racing fuels, straight ethanol, Avgas and liquified petroleum gas (LPG) typically have octane ratings of 110 or significantly higher. Typical "octane booster" additives include tetra-ethyl lead and toluene.

Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction- since higher octane fuels have higher activation energies, it is less likely that a given compression ratio will cause knocking.

It might seem odd that fuels with higher octane ratings burn less easily, yet are popularly thought of as more powerful. Using a fuel with a higher octane lets an engine be run at a higher compression ratio without having problems with knock. Compression is directly related to power (see engine tuning), so engines that require higher octane usually deliver more power. Some high-performance engines are designed to operate with a compression ratio associated with high octane numbers, and thus demand high-octane gasoline. It should be noted that the power output of an engine also depends on the energy content of its fuel, which bears no simple relationship to the octane rating. A common myth amongst petrol consumers is that adding a higher octane fuel to a vehicle's engine will increase its performance and/or lessen its fuel consumption; this is mostly false—engines perform best when using fuel with the octane rating they were designed for and any increase in performance by using a fuel with a different octant rating is minimal. With that said the proper octane for a contemporary engine makes a huge difference vs. a lower then proper octane. Here is a white paper to support that: http://dinancars.com/whitepapersFile.asp?ID=9

The octane rating was developed by the chemist Russell Marker. The selection of n-heptane as the zero point of the scale was due to the availability of very high purity n-heptane, not mixed with other isomers of heptane or octane, distilled from the resin of the Jeffrey Pine. Other sources of heptane produced from crude oil contain a mixture of different isomers with greatly differing ratings, which would not give a precise zero point.

So what all this means is that your 100 Octane RON fuel would be about 95 Octane in the US (R+M)/2. You only need a 92 (R+M)/2 rating so a fuel that is 96 or 97 RON would be correct for your Crossfire. The Shell Premium Unleaded with 95 RON would probably work just fine.

 

Thank you... Thank you... Thank you... I'm very impressed by your diligence and attention to detail.

 

Seconded, I have read a fair bit on fuels and you write up is clearer than most, thanks REDSC400.

I have found the Shell-Optimax does give slightly better performance and lower consumption than a "supermarket" or budget fuel, but the difference is marginal with the Crossfire. On my Landrover Freelander (1.8 petrol efi with 120 bhp) the difference is a little more noticeable.

 

For those in Australia.
Any of the 95 RON or above fuels are fine. I have had a preference for BP Ultimate either 95 RON or 98 RON. There does not appear to be any appreciable performance advantage with the 98 RON that I can attest to. I have had dealings with a person from BP in Melbourne. His official title is "BP Ultimate Brand Champion" (on his business card). He said that there was a different additive in the 98 RON. Allegedly this additive is imported from Europe and it has something to do with increasing RON and engine cleaning or clean burning. Both the 95 RON and 98 RON are sourced from the BP refineries in Queensland (supply for QLD and northern NSW only) or Western Australia (supply the other states and territories).
For "lesser" vehicles using 91 RON the fuel could be sourced from other suppliers and still sold as BP.
Caltex is also available in 95 RON and 98 RON but the 98 RON is only available at a few outlets thus far.
Mobil has 95 RON readily available and 98 RON will become available in the coming months.
The ethanol blended fuels are OK but allegedly can affect rubber etc over a period of time. Up to 10% mix is fine but don't forget that there are monetary advantages, because of excise duty mainly, to the seller if the ethanol volume is increased. Be warned. If the ethanol blend appeals buy only from the outlets owned and operated by the fuel companies to avoid any surprises in mix percentages.

Kind regards.

 

Hi
A friend of mine filled up his BMW 330i with the 100 octane stuff. Here it's called Shell V-Power (*lol*). He promised to feel a slight gain of performance, acceleration. But after we talked a little longer he admitted that it also could have been an illusion only ...

I only put 95 octane in my XF. It's cheaper and works very fine even at high speed (220+ km/h). Tried once 98, but absolutely no difference.

Don't believe the bull$hit they tell in the ads about more power etc.

Cheers

 

It's true that performance gains could be an illusion and if there is a gain it is very small. Consumption though is easier to measure and it is there - only thing is the increase is less than the additional cost.