Octane rating vs. fuel mileage which is best?

[cyclopathic]

I wish I could use E85 here. Have you ever seen the documentary "Pump"? I highly suggest it. I'm wondering if anyone has tried running their Mirage on ethanol.

I ran into issues with E85 west of Mississippi where many non-brand stations were diluting gas with cheaper E85. So you were getting probably something like E30. My motorcycle was overheating from running that lean, I had to pull off freeway.

[cwatkin]

I am not against some ethanol in the gas provided the car is made to run on it. Yes, I know it kills mileage but when was the last time you had to add Heet or similar to your gas since they started adding 10% to most gas? Water in the gas causing problems is a thing of the past due to the ethanol as well as the fact modern fuel systems are sealed. Water that would normally sink to the bottom of the tank now just blends in with the gas and gets included in the mix. Yeah, a lot wouldn't be good but a tiny bit is fine and the ethanol makes this just go right on through. I also understand it is also a great cleaner.

Now the fact it is so heavily subsidized is another story. I like technologies to be able to stand on their own. Yes, I like a domestic and renewable fuel but this stuff is pretty energy intensive to make so not really a green fuel and wouldn't be cheap if not for the subsidies.

You can still find a few stations without ethanol around here. I try to use this for stuff like chainsaws and the like that sit a lot. Otherwise the gas just attracts water as it sits. I am not worried on something that gets used all the time.

Conor

[91cavgt]

http://www.pure-gas.org/

Do a search here to find local gas stations that sell non-ethanol laced gas.

[nickpon]

Mirages are not 'flex fuel' vehicles, as cars designed for E85 are called here in the States.

Haven't done much research outside of the documentary, but it was stated in it that pretty much all cars are able to run ethanol, and the only thing holding them back is the programming of the ECU. There was a guy who changed his Cobalt's ECU settings with a program, and boom, he could run E85 no problem. There's also a site to buy conversion kits. I wonder...

Some places in Canada still sell pure gas, which I would get if my preferred station had it. The drop in fuel mileage is meaningless when you're paying way less for ethanol, but since we're paying the same price as regular gas for E10, we are getting ripped off for sure.

[cwatkin]

Yeah, there are still several stations in my area that have pure gas. I think it is all premium though.

I seem to recall someone on the Geo Metro forum stating that most cars are built for use in Brazil where E85 is quite common. All the lines, fittings, etc. are the same but the ECU as well as the injectors and sensors are different for the US spec cars.

It seems that running E30 in a Metro will not hurt it and has some benefits from time to time. I have heard about issues with anything more. Yes, you do lose mileage when running this.

Conor

[chgruver]

Alright, I have some preliminary numbers here.

With 93 octane, 100% highway driving, speeds between 65 - 70 mph, the car averaged 42.9 mpg. However, my wife was in the passenger seat, we had the A/C cranking the entire time, we ran into a lot of rain during the trip so headlights were on and windshield wipers were used, and I had nine 15 watt solar panels in the trunk!

With 89 octane fuel and the same circumstances above, the car averaged 44.1 mpg.


I have not had a chance to try 87 octane on the highway yet. But so far, it does not appear that higher octane fuel, on the highway, is helping. In city driving it could be different.


More updates to come........

So what was the outcome of this experiment? How did the 87 octane compare to the 89?

[91cavgt]

So what was the outcome of this experiment? How did the 87 octane compare to the 89?

I don't remember the number, but 87 octane was slightly better than 89 octane. I thought in the summer that I might hear a little engine ping on 87 octane here in Texas but it did not happen.

[cwatkin]

I avoid Casey's gas around here. It is cheaper but I have had issues with greatly reduced power and mileage. I am not sure what they do or don't put in this stuff but I have had multiple vehicles run like crap on it and won't get it no matter how cheap it is.

Any brands that seem to do better for the Mirage and likely all others?

Conor

[cyclopathic]

When I tried 87 vs premium the premium was getting 1-2 MPG better, but it had worse cost per mile.

BTW you'll get as much variation from different gas stations, so it could have been due to that not necessarily due to octane reading.

[Eggman]

Any brands that seem to do better for the Mirage and likely all others?

You want to visit TOP TIER Gas. I learned about it here on this website. It lists vendors who sell good stuff. Read more about it at their website, and click on 'Retailers' for a list of members.