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Old 03-15-2012, 07:27 AM   #1
JBW
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higher Octane = Better MPG

i averaged 2.9 more MPG using 93 R+M/2 octane vs 87 per a (2011) 1100 mile MPG compar-o. in addition,(2010) i got similar results from a 3000 mile 87, 89, 93 octane MPG compar-o. as per the higher the octane the better the MPG.
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Old 03-15-2012, 03:24 PM   #2
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I heard that premium gasoline has no ethanol in it like mid-grade and regular gasoline. Could that account for your higher MPG readings? Gasoline with ethanol in it doesn't go as far as pure gasoline.

If you're not sure, I would suggest trying to find a station out there that has ethanol-free gasoline and doing the comparison again.
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Old 03-16-2012, 01:13 AM   #3
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Very few gas stations carry ethanol-free gas anymore but it is usually only available in premium. I would not be surprised if that was the case for this test because a 7% increase in mileage by switching to higher octane is pretty improbable for any vehicle.
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Old 03-16-2012, 04:22 AM   #4
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Notice that he drives a motorcycle. Most bikes are better with premium because thats what they need to run at maximum efficiency.

If a car asks for 87 (regular) octane fuel pumping higher octane fuel will only retard the timing thus reducing the performance and efficiency of the engine.

I would not pump premium fuel in a vehicle unless it is recommended to do so.

As far as ethanol-free gas goes, Petro-Canada and Shell seem to be the only brand in Atlantic Canada to carry it.: in all grades that is.

I've only pumped fuel that included up to 10% ethanol twice and DID notice the difference in MPG although I do not have enough data collected to experience different brands of fuel. I fill-up at Shell 98% of the time.
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Old 03-16-2012, 04:48 AM   #5
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ethanol blend is about i can get here in ohio. and i use sta-bil ethanol treatment.
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Old 03-16-2012, 05:00 AM   #6
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i noticed drop in MPG 2010 with ethanol blend fuel. i started using sta-bil marine ethanol treatment. i got back the lost MPG. one bottle treats 100 gals.. so its cost effictive.
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Old 03-28-2012, 10:55 AM   #7
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Higher octane rating alone cannot account for increased MPG, as it contains less energy than lower rated fuels.

Your experiment is a bit flawed.

Do some research on octane ratings and you will see this is true.
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Old 03-30-2012, 03:16 AM   #8
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That is just an unfortunately propogated bit of "internet wisdom." The two contain virtually the same amount of energy. The difference is that you can run a more aggressive fuel or spark tune with higher octane, to extract more useful energy out of the fuel, instead of dumping it out the radiator as waste heat.

I still wouldn't expect to see a 7%+ increase by switching to premium, and I especially wouldn't expect an ounce of magic elixir make an entire tank of E10 give the same mileage as pure gas.
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Old 03-30-2012, 10:47 AM   #9
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Just to add and clarify. Higher octane actually raises the detonation point of the fuel so its harder to ignite. This is for higher compression engines, typically found in higher performance vehicles. Using premium for a regular engine car is not going to benefit you much, if anything. But if you have a car that requires premium, using non-premium can actually cause spark knock.

And speaking of spark knock, if you are suffering from that with your current octane level of fuel, go up one level and see if that helps make it quit. Spark knock is premature detonation of fuel, which means your engine actually needs a higher octane to prevent it from doing that.

Having said all that, many modern engine/computer systems can adjust some to compensate for incorrect fuel to a point, but you really should use what it is called for.
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Old 04-04-2012, 12:54 AM   #10
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v-strom is running 11.3:1 C.R. so, i'm probably getting some detonation with the 87 octane fuel. which explains why i'm getting better mpg with the 93 octane.
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