What's the deal with Unleaded 88?

[SHOZ]

The one Caseys close to me with the U88 is 3.04 a gal and E10 87 oct is 3.19. E10 91 oct is 3.79. Time for a fill on the turbo.

IL State taxes are gasoline/gasohol – $0.454 per gallon plus a 7.5% sales tax (and any city or county sales tax)
$0.008 a gallon environmental impact fee and $0.003 a gallon Underground Storage Tank tax. Plus the Federal tax of course, 18.4 cents per gallon. Total of .649 + 7.5%. So $2.39 is the base price before fees and taxes.

 

[turboseize]

Using anything but pure gas will affect your efficiency (gas mileage) by an approximate degradation as shown above, all other things being held constant.

Correct, but real-world mileage may well be even better than what energy density would lead you to assume.
Higher octane may allow the ECU to run more aggressive spark advance, which will help efficiency. Also, different vapor pressure of alcohol content will affect how fast and homogenous the fuel-air mixture is formed. Alcohol content will also affect how much fuel condenses on intake parts at cold starts...
In my experience, the latter two effects are very dependent on temperature. In summer, the vapor pressure aiding fuel atomization is a great benefit. I've run up to e20 or e30 without significant mileage penalty in summer. In winter however any alcohol content really hurts mileage compared to "straight" petrol, especially when short tripping.

 

[eljefino]

You guys are all focussed on the octane. Ethanol is also an oxygenate. When burned, it releases oxygen, and at greater concentration than the 21 percent in the air. Properly tuned,you can get a tiny bit more horsepower from the stuff.

I'm thinking they know it's not a full 15 percent right now, and are trying to change peoples' habits. One tank won't hurt ya.

 

[Jay3702]

I put this stuff in my telluride on accident. J didn’t notice any difference

 

[Leo99]

I'm old enough that we needed to specify unleaded years ago, but it seems strange that we still call it unleaded in 2023.

 

[dishdude]

I'm old enough that we needed to specify unleaded years ago, but it seems strange that we still call it unleaded in 2023.

At least they quit requiring UNLEADED FUEL ONLY be labeled on the gauge cluster.

 

[eljefino]

Until not too long ago it was part of a Maine state inspection to verify the unleaded restrictor was still installed in the filler neck.

 

[SHOZ]

I had a 1979 Mustang with the 4 cylinder. It knocked like crazy under load on the old unleaded 87 oct. Then they started selling the E10 87 and it never knocked again. During that time, 1980 or so, was when a lot of dirty fuel problems arose, like when they went to the biodiesel.

 

[brianl703]

I had a 1979 Mustang with the 4 cylinder. It knocked like crazy under load on the old unleaded 87 oct. Then they started selling the E10 87 and it never knocked again. During that time, 1980 or so, was when a lot of dirty fuel problems arose, like when they went to the biodiesel.

The E10 gas of that era was actually higher in octane than 87, because it was 10% ethanol and 90% 87 octane gas.

That is no longer true. Now E10 is 10% ethanol and 90% "BOB" gas, "before oxygenate blending", which has an octane of 85-86. The addition of 10% ethanol brings it to 87 octane.

 

[SHOZ]

The E10 gas of that era was actually higher in octane than 87, because it was 10% ethanol and 90% 87 octane gas.

That is no longer true. Now E10 is 10% ethanol and 90% "BOB" gas, "before oxygenate blending", which has an octane of 85-86. The addition of 10% ethanol brings it to 87 octane.

And engine design/management have greatly improved. That Mustang was my last carbureted car.

 

[tmorris1]

The E10 gas of that era was actually higher in octane than 87, because it was 10% ethanol and 90% 87 octane gas.

That is no longer true. Now E10 is 10% ethanol and 90% "BOB" gas, "before oxygenate blending", which has an octane of 85-86. The addition of 10% ethanol brings it to 87 octane.

It used to be sold as 90 Octane if I remember right.

 

[TiGeo]

Unless your vehicle is really old 5% more E isn't going to hurt a thing beyond dropping the mpgs v. slightly and likely not enough to offset the cost differential.

 

[brianl703]

Unless your vehicle is really old 5% more E isn't going to hurt a thing beyond dropping the mpgs v. slightly and likely not enough to offset the cost differential.

Probably anything with oxygen sensors is going to be fine with it.

 

[mjk1967]

Every pump I've seen in MN states clearly that the Unleaded 88/E15 is fine for vehicles that are 2001 or newer.....
I personally will use it here/there, if I see a .25 cent price difference between 88 and 87. There will be a small drop in mpg...

 

[tmorris1]

Every pump I've seen in MN states clearly that the Unleaded 88/E15 is fine for vehicles that are 2001 or newer.....
I personally will use it here/there, if I see a .25 cent price difference between 88 and 87. There will be a small drop in mpg...

I have ran a lot of 88/E15 and the real world MPG loss is small enough that I can't notice it in my calculations. I log every tank of fuel in my 2006 Focus work car and it doesn't show any difference, but the savings is $.05 - .20 a gallon depending on where you buy it.

 

[spasm3]

E85 is actually 51-83% alcohol. (lower in the winter)

E15 aka "super 88" is upto 15% usually no where near 15%-- typically made with a blender pump mixing the e85 with 87 octane RUG(regular unleaded gas)-- which is usually upto 10% alcohol.

e10 is alcohol % is whatever was delivered as RUG.

Ethanol free is also delivered and held in a separate storage tank.

So if your e10 is lower -- and it usually is.. your e15 wont be close to e15.. esp. in winter when the flex fuel is closer to 50% alcohol than in the summer when its 80% Alcohol.

Using a tester the highest I've ever seen was 12% alcohol in e88 usually its about 10% esp in the winter.

RUG from a few stations is usually 6%-7%

I wouldnt use super 88 in OPE but any modern car should have 0 issues with it.

The savings last week was 70cents currently about $1 cheaper. typically it runs around 3 to 35cents cheaper.

Do they reduce the ETOH percentage in E-85 and E-10 and E-15 in the winter?

 

[Rand]

Do they reduce the ETOH percentage in E-85 and E-10 and E-15 in the winter?

They reduce the ethanol content in winter for e85 so it combusts better in the cold... which varies between 51% and 83%
It is blended at the pump to produce the e15/super 88 (87+E85=E15)
so the ethanol content in that also goes down.
AFAIK the content of the 87 octane "e10" varies but not by season Usually 5%-6% when I've tested it I had 7% a couple times but you have to realize my test isnt digital... There is about a 1% margin for error.

I've only tested e15 a few times recently but I got 11% once and 10% twice.
I have to remember to bring a gas can if I want to check it.
I'd like to check it when we get to mid December to see if the content is actually much lower.

 

[Astro14]

Every pump I've seen in MN states clearly that the Unleaded 88/E15 is fine for vehicles that are 2001 or newer.....
I personally will use it here/there, if I see a .25 cent price difference between 88 and 87. There will be a small drop in mpg...

I see, so if the state says it is OK, but the owner’s manual says this:

Specifically stating that you cannot use fuel that exceeds 10% oxygenate, including ethanol - Go with what the state tells you?

Ignoring the specific guidance of the manufacturer?

Do you also do what the state tells you for an oil change interval?

 

[addyguy]

I’d love to run 88 E-15 if I could, but it’s not sold up here. Slightly higher octane, and a bit more alcohol in the fuel to prevent freezing, and possibly clean the system a bit more? Yeah, I’d have that in every tank if I could.

 

[Rmay635703]

I see, so if the state says it is OK, but the owner’s manual says this:

View attachment 190317

Specifically stating that you cannot use fuel that exceeds 10% oxygenate, including ethanol - Go with what the state tells you?

Ignoring the specific guidance of the manufacturer?

Do you also do what the state tells you for an oil change interval?

As you might have read above e15 is rarely more than 12% ethanol
Just as e10 is rarely more than 7% ethanol