Avoid ethanol belnd fuel

[babacu]

Some info about the octane rating variations (from http://en.wikipedia.org/wiki/Octane_rating)

Generally, octane ratings are higher in Europe than they are in North America and most other parts of the world. This is especially true when comparing the lowest available octane level in each country. In many parts of Europe, 95 RON (90-91 AKI) is the minimum available standard, with 97/98 RON being higher specification (being called Super Unleaded). The higher rating seen in Europe is an artifact of a different underlying measuring procedure. In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in Canada, 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 8 to 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 "regular" gasoline in Canada and the US, would be 91-92 in Europe. However most European pumps deliver 95 (RON) as "regular", equivalent to 90–91 US AKI=(R+M)/2, and deliver 98, 99 or 100 (RON) (93-94 AKI) labeled as Super Unleaded - thus regular petrol sold in much of Europe corresponds to premium sold in the United States.

[TheHolyGhost]

That's good information thanks, Babacu.

[will2k]

Ahhh nice that explains a lot!

[GREG]

all the grades of gas here have around 10% (cant remember if that is min or max) but i usually run regular and put in about 1-2 ounces of Stabil Marine formula for ethanol every other fill-up, usually around 9-10 gallons. Right now I'm getting 28.3 average by the math over 1350 miles (cvt-awd).

[Moto]

typically "up to 10%"

[KizashiSLS11]

What brand of fuel are you guys using?

[~tc~]

i was reading an article once that explained "premium" fuel actually has less units of energy in it, so in a sense you should not get better mpg with premium.

This is essentially true. The octane rating is essentially, how resistant it is to detonation. Higher number = less explosive.

You should always run the lowest octane your engine can run without detonation (knock or ping).

Now, from there, it gets a bit more complicated relating to charge density and flame front speeds and all kinds of minutae about the actual process of exploding the fuel, and if you start running forced induction, etc, these things start to have an impact.

Of course, if it was a gas direct-injection engine (as I wish it were), we wouldn't have to worry about it ...

[gentle_ben]

It's weird because here in Australia normal fuel is 91 Octane then there's 95 and 98.

I used 95 for a bit and got good mileage and performance and now im trying the 98. I didn't like the 91 octane here that much but the 95 seemed very good so i'll probably go back to that.

The way they measure octane in fuel is different in Australia than in North America. When I lived in Australia I researched it b.c. it irritated me that we had such low octane fuel back home in comparison.

I've put 91 octane in our Kizashi a few times in a row to measure the difference over 87 octane and there was no difference at all.

[Eric998765]

You people saying how much of a waste 91 is are cracking me up. We have I think a 16gal tank. If regular is 3.80 and premium is 4.00, then that is a difference of ((4.00*16)-(3.80*16))=$3.20. I would rather have less engine knocking after a few dozen thousand miles than save a whopping 3 bucks on a tank that is already costing me $50+

[hocaspocas]

Good calculation, I would pay the extra 4 dollars to keep my engine running smoother. By the way, i see some of you filling up your tank with gas without ethanol. Where or which gas station in north america are you buying your gas? Every gas station I go it says they are using the 90% gas +10% ethanol.