Here in australia the highest fuel octane level is 98 octane SHELL OPTIMAX. i am told that this is suitable for the rx8 but the rx8 mazdaspeed may not be coming to australia becouse it needs a higher octane level than currently in australia .What is the optimum octane level at which both the rx8 and the mazdaspeed rx8 operate to its upmost performance level??? What fuel is available in your part of the world , i know that we miss out on quite a few high production cars becouse of our low octane levels .

 

since when is 98 low!??!?

here is cali we get the **** water known as 91 octane

 

california octane ratings are pump octane numbers (PON) which is an average of motor (MON) and research octane numbers (RON). i suspect the 98 australian octane is research octane which is about the equivalent to our 89 or 91 octane here.

 

Well if that is the same Shell Optimax that we use here in the UK, then lefuton is correct, it is 98RON.

 

And also the highest octane in the UK.

 

you may find this link useful


http://www.btinternet.com/~madmole/R...RONMONPON.html

 

I've seen as low as 86 and as high as 93 PON, that's about it

 

That sounds about right. Thanks for the link lefuton.

If you believe what the website says then our fuel rating seems to indicate that we get the same general quality of fuel.

The lowest grade you can get here in the UK is 95RON, which is roughly equivalent to 91PON.

Now if only we can get the prices the same. :D

Shahpor

 

well, that's not quite the case as the refinement process for different countries would omit or include different chemicals or levels of cleanliness dependant upon certain federal laws... for instance, we in Canada have very sulfurous gasoline (don't ask me why), and it ruins our emissions equipment in our cars, but also kinda does a number on the emissions checking equipment (or so i hear)...

so, there is more to it than the octane rating... just wanted to add a little aside. (i know that we probably don't care about anything other than the rating anyways )

 

I agree with wakeech absolutely, and that chart is a GROSS oversimplification - some batches/formulations will be almost the same MON as RON, some WAY apart.
Chemicals can make a big difference, as can base stocks. (In winter 'they' can add lots of Butane, which has a lovely octane rating, up to 10% of a blend, but it is wee-wee for power!)
Once again let me hint about sulfur levels, the refinery you would be getting your gas from would be the 'low-sulfur-award-winning' Sarnia plant, if your brand rhymes with SMELL.
The U.K. has always measured RON+MON/2 as far as I know, and cannot by law state just the RON on the pump - and why would you care about JUST the RON anyway, it is meaningless without the MON?
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Doc

 

i wouldn't say it's meaningless with only the RON but then you could still be left with an overly sensitive fuel and have a low MON

and yes i totally agree it's a gross simplification, but it atleast explains the disparity of the numbers in different nations. when i was in south america, all gas was listed as 94/98/104 octane.. i never really looked to see if it was RON but it would seem that that would be a reasonably safe assumption.

stuff like this makes me kinda glad i live in cali...even if our registration fees and emission laws are getting of hand.

 

As far as I know, here in the UK it is measured in RON. On the pump it states, for example, 98RON.

Also, the website does state that it is a general measurement and that different batches of fuel have different properties.

I, for one, would never put supermarket fuel in my car as I have been told that it is of bad quality.

Shahpor

 

Supermarket fuel is the same fuel you get from any petrol station in the area.

The fuel all comes from the same refinery, whats different is the additives each company (tesco, shell etc) add before it gets to the pump.

Half the cars on the roads dont have knock sensors and wont take advantage of higher octane fuel, if you use optimax (for example) in one of those ALL the benifit is comming from the detergents, might as well use some redx/injection cleaner every 5k.

 

OK, maybe quality is a bad word to use. But the additives also contribute to how well the car will run and I have noticed that my car does run better when I put Optimax in it in relation to supermarket fuels.

Shahpor