Worse m.p.g. Using higher octane

[Racket]

I've not seen 86 octane - is it sold at high altitude?

As far as ethanol percentage I believe the 94 octane E30 at Sunoco gave me as good mileage as the up-to 10% ethanol 93 octane at Sam's club. The minimum I run is 89 octane - which is what the tune Torrie at Unleashed built for me.

I get mid 24 MPG on the highway - would probably do better at sub-70 MPH.

The only ethanol free gas I find is 87 octane and it costs near as much as premium.

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[ScrappyLaptop]

I think it depends on how the 91 octane is formulated. If they do it partially or totally with additional ethanol, milage could be worse than that using E-0 non-oxy premium. I only ran two tanks of 91 oct E-0, and that was when the truck had less than a thousand miles, and we were in the Black Hills. Later drove home against the wind at 80mph, so I don't have a fair comparison with 87oct E-10.
I have never reset the Fuel economy page in the Driver Information Display since news after 5167 miles I've averaged 24.4 mpg and 49 mph all but those two tanks mentioned earlier on 87oct E10

You may have something there. Ethanol has about 10% less energy than gasoline, so the portion of the fuel that is ethanol will get 10% less mpg. Ethanol itself has an octane rating of 118. The octane rating for E15 (15% ethanol) is 88 octane and E85 (85% ethanol) is 108 octane.

It would be somewhat ironic if gas stations are providing the higher octane fuel required by more fuel efficient engines, but because they're using ethanol to get that higher octane rating, the fuel results in lower miles per gallon.

 

[BassRanger]

Yes it's possible. Depending on what your station is using to boost octane, it's very possible for higher octane to have a lower stoich point and require more fuel.

 

[Porpoise Hork]

Is it possible? I usually use 86 octane,friday I was down to half a tank and filled up with 88 octane (philips 66),I can usually go 100 miles before it gets to 3/4 of a tank,right now I’m at 78 miles already at 3/4 of a tank

Sometimes you can get a tank of bad gas. Oh it'll run OK but the mileage will be utter crap. Other times it could just be the pump auto cut-off stopped early and the tank wasn't as full as you think it actually was causing the difference.

 

[ScrappyLaptop]

Yes it's possible. Depending on what your station is using to boost octane, it's very possible for higher octane to have a lower stoich point and require more fuel.

Not to get too far OT, but...
The official reason for the ethanol is to create less emissions.
Yet burning ethanol itself creates CO2.
And blending it in lowers gasoline's miles per gallon, thus creating more emissions.
At some point it starts to feel a bit like a corn growers' lobby shell game.

 

[dondonbabyraptor]

Better than my 15 MPG. I think there are way too many factors to consider to get too crazy over it. Gasoline changes, varying gases at different stations, varying ethanol, varying driving habit changes(even unconsciously), computer MPG being not accurate to the highest degree, more highway vs street or more street vs highway during certain weeks, that one time you decided to drive harder to reach your destination, that one time you decided you were tired and wanted a relaxing drive near or under speed limit, etc etc. You get my point, enjoy the Ranger and forget about the little nuances

 

[t4thfavor]

Over a fairly long period of time I have been getting 8-10 mpg using 87 octane pure gasoline and 10-11 mpg using 93 octane pure gasoline while towing my camper. I attribute this to less knock under load requiring less fuel to compensate for.

 

[Motorpsychology]

In Florida our regular octane is 87. I have occasionally seen 88 offered alongside it (and wondered why). Someone told me the 88 contains more ethanol than the 87, which could explain lower efficiency/mpg despite the higher octane.

Look at the pump carefully, most 88-89 octane is E-15 around here. The selector on the pump should be labelled as such. The label is there to warn of damage to small engines, motorcycles, boat motors, etc.

 

[BlackRanger01]

I've not seen 86 octane - is it sold at high altitude?

As far as ethanol percentage I believe the 94 octane E30 at Sunoco gave me as good mileage as the up-to 10% ethanol 93 octane at Sam's club. The minimum I run is 89 octane - which is what the tune Torrie at Unleashed built for me.

I get mid 24 MPG on the highway - would probably do better at sub-70 MPH.

The only ethanol free gas I find is 87 octane and it costs near as much as premium.

Had 85 octane in Montana in 90s. Had it in old escort and didn't have an issue.

 

[Apples]

Pure octane isn't the only issue. The Reid Vapor pressure rating is changed based on the local ambient. Thus individual ratings from one to another supplier is to be assumed.

 

[JohnnyO]

You can't make a judgement from one tank. Need to run 3 to 5 tanks consecutively to see if it makes a difference.

Could the 88 Octane have more ethanol in it?

And it usually take 2-3 tanks full to see a change with different octane rules are used. And since you only put half a tank in, it is possible that you got some bad fuel.

I run E15 88 octane a little more than half the time and see no mpg difference between that and regular 87. Stickers on the pumps around here say that 87 may have up to 10% ethanol and the E15 may have up to 15%. I have a credit card for a regional convenience store chain and some locations have E15 and some don't. I'll save the 10-20 cents a gallon when I can.

 

[12Bravo20]

Around me, the choices are 87, 89, 91, or 93 octane. And most of it contains up to 10% ethanol unless you somewhere that carries 91 or 93 ethanol free gas. I've been running either 91 or 93 in my Ranger since new. Not all stations have 91 and 93, it is one or the other.

 

[CB750F]

OMG, not this again.
OP, your talking about 1/4 tank of gas, that's nothing, try 5 tanks & see
what it does.
Please google "What is octane"
First thing that comes up is:
" Octane ratings are measures of fuel stability. These ratings are based on the pressure at which a fuel will spontaneously combust (auto-ignite) "

So, a low octane will pre-detonate in a high compression engine & will
cause what is known as pinging or knocking. This means as the piston
goes up it is compressing the gas & air & will go BOOM before the
spark plug goes on. This will cause stress on the piston, as it is still
going up & unfortunately will cause stress on all the parts below the piston. ( This is just, bad!)
Someone mentioned an NA (natural aspired) as opposed to FI (forced induction) turbo/supper charger will use 87. Not true, low compression engine will use lower octane & high compression will use a higher octane.
My BRZ is NA, high compression 12:1, I need 91 or more. Ranger can use 87,
with a turbo engine, as it has a compression ratio of 10:1(low).
The only thing higher octane may/does(?) have is better detergents.
The day I tow, I will use 91, till then, 87 it is, as per FoMoCo & their
documentation with the book provided with our trucks.
Edit - Oups, my bad, seem u can get 30 more hp with higher octane....
So a little more power & better detergent with higher octane.

I ain't no scientist nor do I think I know WTF I'm talking about, just a dude
on the internet, believe with caution.

 

[Josebd]

Filled up this morning with 88 octane,haven’t found 87 yet,made a short trip to a close little city,came back home,84 miles round trip,yes I know that ain’t crap,I know I should go further,but don’t plan to anytime soon,I don’t use it for work,I have company pickup
and it did pretty darn good,a lot better than the stop and go that I did before this fill up,so I guess I was just being a little paranoid,only got a little over 2000 miles on it total,maybe the 86 octane didn’t hurt it any? I learned my lesson guys so be gentle
after the little trip lol

 

[D Fresh]

OMG, not this again.
OP, your talking about 1/4 tank of gas, that's nothing, try 5 tanks & see
what it does.
Please google "What is octane"
First thing that comes up is:
" Octane ratings are measures of fuel stability. These ratings are based on the pressure at which a fuel will spontaneously combust (auto-ignite) "

So, a low octane will pre-detonate in a high compression engine & will
cause what is known as pinging or knocking. This means as the piston
goes up it is compressing the gas & air & will go BOOM before the
spark plug goes on. This will cause stress on the piston, as it is still
going up & unfortunately will cause stress on all the parts below the piston. ( This is just, bad!)
Someone mentioned an NA (natural aspired) as opposed to FI (forced induction) turbo/supper charger will use 87. Not true, low compression engine will use lower octane & high compression will use a higher octane.
My BRZ is NA, high compression 12:1, I need 91 or more. Ranger can use 87,
with a turbo engine, as it has a compression ratio of 10:1(low).
The only thing higher octane may/does(?) have is better detergents.
The day I tow, I will use 91, till then, 87 it is, as per FoMoCo & their
documentation with the book provided with our trucks.
Edit - Oups, my bad, seem u can get 30 more hp with higher octane....
So a little more power & better detergent with higher octane.

I ain't no scientist nor do I think I know WTF I'm talking about, just a dude
on the internet, believe with caution.

Very few NA engines have a high enough compression ratio to require higher octane fuels. Unless you're talking about motorcycles.

And no midsize trucks in the US market with NA engines are one of them.

Perhaps I should've said, "if you want to put cheap gas in your midsized truck you should've bought one with a NA engine."

Putting 87 in a small displacement turbo engine is not a good idea. No matter what Ford says.

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