Thread: E10

Originally Posted by Hoges

I think you may find that 98 Octane is taken from a narrower "band" in the refinery distillation process and is therefore a more consistent 'mix' .
Ethanol may have a higher RON but the calorific value of ethanol is way below the olefines which constitute the majority of the so-called 'petrol' mix. So a 10% ethanol mix does not have as much energy as an equivalent volume of say, 95 Octane or even 91 Octane.

My nephew has a 1929 Chev...he tells me that he (and other club members) run the Chev on Shell 98 octane... no additives. The valve seats have not needed attention...

Bang for buck, or cost per calorie, E10 offers less value than 91. E10 needs to be 6cpl cheaper than 91 to offer equivalent calories per dollar.

Originally Posted by Hoges

I think you may find that 98 Octane is taken from a narrower "band" in the refinery distillation process and is therefore a more consistent 'mix' .
Ethanol may have a higher RON but the calorific value of ethanol is way below the olefines which constitute the majority of the so-called 'petrol' mix. So a 10% ethanol mix does not have as much energy as an equivalent volume of say, 95 Octane or even 91 Octane.

My nephew has a 1929 Chev...he tells me that he (and other club members) run their Chevs on Shell 98 octane... no additives. The valve seats have not needed attention...

Hi Hoges,
No argument that Ethanol has a 3% lower calorific value than that of Naphtha ( which would have some component of olefin), that's why it's cheaper. Calorific value and Ron values are completely different. If you add enough ethanol (Ron of 120) to 91 you will be able to get 95 ( I think it's E20ish). In a few outlets in NSW, United sells E85 (RON of 105) so the tappet heads can rechip (factory option) their BMW's and Mercedes to tear up the pavement.

BTW I am pretty sure that 91, 95 and 98 have the same calorific value (or within cooee of each other), but try to find actual published values that Australian fuel companies are selling their fuel at, they make vague "feel good" statements but no numbers. Here is the fuel standard - Fuel Quality Standards (Petrol) Determination 2019, it actually does not talk about calorific value.

I know that 98 will burn better than 91 but that is as much of motor issue as a fuel issue, in my opinion, Car manufactures are specifying 95 for their engines so they can meet emission standards (required in international markets) without having to do as much work.

95, 98 are made from 91 with blended/added components (mostly aromatics) , and they will use octane boosters to get the rest of the way up to the octane number they need. In Australia they can use (without needing to tell you about it) a range of "herbs and spices", which I believe include, Ethanol, butanol, NMA and a couple of others that I can't recall.

Lead was used as an octane booster because it was cheap, so leaded fuel had a higher octane number, not surprised that the older cars run on 98 without problems, I wonder though if they do enough miles though to find out if the valve seats hold out. If I recall correctly lead also reduced the temperature of the flame front in the cylinders (well I think that's what Ed said anyway).

Oddly enough the USA has gone on past the E10 thing, as 90% of their petrol sold is E10 where as it's only around 20 - 25% in Australia.

Cheers Glen

Originally Posted by Dorian

Hi Hoges,
BTW I am pretty sure that 91, 95 and 98 have the same calorific value (or within cooee of each other),

It is all the same basic petrol and as you have said has the same calorific value so in an engine with a fixed state of tune all will provide the same power. However higher octane rating allows higher states of tune to be dialled in so more power releasing the fuels full potential.

If you have an engine tuned to run on 91RON, putting in 95 or 98 makes absolutely no difference except draining the wallet a bit quicker. But increase the advance, increase compression, etc etc then higher octane fuel comes into its own.

Yes, we run our Mazda 2 happily on E10 94. I did try 98 in it once, but couldn't see any difference to performance or fuel economy, so the extra cost seemed worthless.

I have read that many European cars have to be detuned for Australia, but I believe that is because our fuel is dirty and does not meet the cleanest fuel standards they are tuned to run on, causing dirty filters and DPFs.

Originally Posted by DiscoMick

Yes, we run our Mazda 2 happily on E10 94. I did try 98 in it once, but couldn't see any difference to performance or fuel economy, so the extra cost seemed worthless.

I have read that many European cars have to be detuned for Australia, but I believe that is because our fuel is dirty and does not meet the cleanest fuel standards they are tuned to run on, causing dirty filters and DPFs.

Matches their thinking…

Your vehicle is tuned for 91 and the E10 will have similar power.

Mazda states nothing above E10 on Euro fuel



Note that in some countries E20 is offered - however warranty is significantly shorter in those regions.

Originally Posted by V8Ian

Bang for buck, or cost per calorie, E10 offers less value than 91. E10 needs to be 6cpl cheaper than 91 to offer equivalent calories per dollar.

They should mention that on the fuel price watch type websites.

Originally Posted by V8Ian

Bang for buck, or cost per calorie, E10 offers less value than 91. E10 needs to be 6cpl cheaper than 91 to offer equivalent calories per dollar.

That's odd, we get better performance and kilometres with e10 than 91 in our y62. We get very similar outcomes with e10, 95 and 98, but can definitely see the difference when using 91.

Originally Posted by Vern

That's odd, we get better performance and kilometres with e10 than 91 in our y62. We get very similar outcomes with e10, 95 and 98, but can definitely see the difference when using 91.

That could be down to ignition timing or compression. The higher the RON, the slower and longer the burn.