What's the deal with Unleaded 88?

[MNgopher]

So much confusing E15 and E85 in this thread.

E15 is sometimes called Super 88 here.

I run E15 in my 2016 F150, 2017 Fusion, and 2021 Explorer, anytime its priced more than 10 cents cheaper per gallon than 87 E10. I've run it for 10's of thousands of miles with zero issue. All three vehicles state in the owners manual and right on the fuel filler door than the use of anything from E0 to E15 is acceptable.

As an example, the neighborhood station is currently at 3.249 for regular 87 E10. Super 88 is at 3.049.

 

[SHOZ]

On this subject for reasons unknown e15 varies from 10%~15% ethanol and it’s actually rare it’s on the upper edge.

I’ve found the only time I experience measurable fuel economy loss on e15 is during winter months.

I’ve also found it outperforms normal 89 octane fuel on knock counts.

Considering it can be up to 50 cents a gallon cheaper than even RUG (at one specific local station) I tend to run it almost exclusively in place of premium fuel in my one car that specs e15 or premium in the manual.

My other cars I run it when there is a good price spread, sadly recently it’s sometimes MORE per gallon than RUG, was almost tempted to send a letter to the station considering how ideotic that is.

I'm tempted to try in in my tuned turbo. It's set for 91 oct but I never hear any and have a monitor alarm with my Torque setup. For my lazy driving it would probably be OK. In fact I need a tank for the winter as it sits if any snow is around.

 

[brianl703]

I guess that depends on how old your ECU is as the whether it would throw CELs for Bank 1 and/or Bank 2 too rich? I really don't know as it isn't a fuel grade around here.

Everything I've ever read on the subject is that the ECU (OBD-II ECUs) can correct for up to a 25% deviation from the base fueling tables, which translates to being able to use about a 50/50 mix of E10 and E85 before a CEL comes on.

 

[SHOZ]

I'm tempted to try in in my tuned turbo. It's set for 91 oct but I never hear any and have a monitor alarm with my Torque setup. For my lazy driving it would probably be OK. In fact I need a tank for the winter as it sits if any snow is around.

For normal driving I doubt if you ever hit the limit on static the fuel trim tables unless other issues. And most ECUs cut out the O2 sensor at WOT.

I have a WBO2 on it to see what would happen. I'm sure the timing would be trimmed under heavy load.

 

[Delta]

I've been running it in the Tacoma the past couple tanks again as it has been $2.99/gal VS $3.63. I can say I'm not going to run it again if I can try. Engine doesn't idle as good and somewhat down on performance (well it is a 3.5L V6 Tacoma, so there wasn't much there to start off with). Fuel mileage has been less, but I can't really be sure on that as the temperature has been dropping.

We have a Rutter's in town and they have top tier gas, but it's the most expensive at $3.75/gal.

I typically get gas in Maryland as I work in that state (I live a couple minutes from the border) and there's a station with good fuel right down from where I work. Filled up the Subuwu last week at $3.09/gal for 87 E10.

 

[brianl703]

I get 25-26MPG using E15 in my 1998 Nissan Frontier 2.4L I4. About the same as using E10.

 

[mattwithcats]

Careful when you fill up.

The E88 may be on a separate hose, with the E85 gas.

You must select the correct grade…

 

[jayjr1105]

Careful when you fill up.

The E88 may be on a separate hose, with the E85 gas.

You must select the correct grade…

At Sheetz it's...
Black - Normal E10 3 different Octane to choose from
Green - Auto Diesel
Yellow - E85
Blue - E15 (88oct)
Red - Ethanol Free

 

[Pew]

Everything I've ever read on the subject is that the ECU (OBD-II ECUs) can correct for up to a 25% deviation from the base fueling tables, which translates to being able to use about a 50/50 mix of E10 and E85 before a CEL comes on.

The Evo has a +-15% correction factor but I don't know if that translates to other MAF equipped cars. Folks can put on a 2.75" intake versus the stock 2.5" and not have to adjust the tables but the most common intake upgrades to a 3" will have to be adjusted.

 

[Delta]

At Sheetz it's...
Black - Normal E10 3 different Octane to choose from
Green - Auto Diesel
Yellow - E85
Blue - E15 (88oct)
Red - Ethanol Free

That must be the new Sheetz configuration. They built a completely brand new one and bulldozed/rebuilt another one near me. Both have that exact layout on the pumps. I'm not complaining though; I like the fact I only got to drive 10-15 minutes down the road for ethanol free for the mowers/snow blower.

 

[Speedy3861]

I may be mistaken or misinformed, but it seems that the only folks that derive any benefit from ethanol are the people involved in it's production, raises octane somewhat but actually has less caloric energy, essentially 87 octane with 10% ethanol generally delivers 10% less mpg due to this vs 87 ethanol free fuel. I know it has raised the price of beef as the price of corn has risen as corn production shifted to ethanol production. The average user who Is largely uninformed about fuels, octane, etc, seeing "88" thinking it "better" than 87 is motivated by price to use it. Most consumers have absolutely no concept or understanding of what Toptier is all about and are usually convinced the 93 or "Premium" is better gas regardless of if their vehicle needs it or not. Sheetz marketing it as 88 octane is somewhat deceptive. I'll continue on a related subject, how many vehicle owners even have a accurate tire gauge or know how to use it?

 

[kschachn]

I may be mistaken or misinformed, but it seems that the only folks that derive any benefit from ethanol are the people involved in it's production, raises octane somewhat but actually has less caloric energy, essentially 87 octane with 10% ethanol generally delivers 10% less mpg due to this vs 87 ethanol free fuel. I know it has raised the price of beef as the price of corn has risen as corn production shifted to ethanol production. The average user who Is largely uninformed about fuels, octane, etc, seeing "88" thinking it "better" than 87 is motivated by price to use it. Most consumers have absolutely no concept or understanding of what Toptier is all about and are usually convinced the 93 or "Premium" is better gas regardless of if their vehicle needs it or not. Sheetz marketing it as 88 octane is somewhat deceptive. I'll continue on a related subject, how many vehicle owners even have a accurate tire gauge or know how to use it?

It's nowhere near 10%. Where did you get that number?

And how is the octane rating deceptive?

 

[dnewton3]

Ethanol has significantly less energy than typical gasoline for any given unit of measure. Ethanol averages about 75k BTUs per gallon.
https://afdc.energy.gov/files/u/publication/ethanol_basics.pdf

Straight gasoline has around 120k BTUs per gallon. (I've seen numbers as high as 125k, and as low as 115k, so I'll use the average of 120k/gal)
https://www.eia.gov/energyexplained/units-and-calculators/british-thermal-units.php

Diesel has even more energy than gasoline; about 137k BTUs per gallon.
https://www.eia.gov/energyexplained/units-and-calculators/british-thermal-units.php


Hence, pure ethanol is only about 63% as energy dense as pure gasoline. (75k is 63% of 120k)

So, if you had a gallon of E10, then 10% of that total volume would have about 1/3 less energy by volume. Hence, one tenth of the gallon would be down 35% on energy. Using E88 (which can be up to 15% ethanol), it would lose even more energy; 15% of the total volume would be down 35% of BTU energy.


Now, there are other things in typical gasoline; even things like butane (believe it or not), depending on season and location. So we'll have to just work with some broad averages here; don't nitpick and flame the nuances. Also, we should all understand that any engine could be "tuned" to maximize the specific fuel used, but we're talking about general cars which are E85 capable, and therefore can run on anything "up to" 85% ethanol. Many drag racers can "tune" engines for what they affectionately call "alcohol", which allows a MUCH higher compression ratio without fear of pre-detonation. That in turn changes the thermal performance of an engine. But we're going to stick with a "normal" engine here for my examples below. Consider an example of an E85 capable 3.5L n/a Ford Cyclone engine (in a Taurus) ...

If your car is capable of running one or more of the fuel compositions below, this is how it would play out:
If you had a 10 gallon tank of pure gas, it would be holding 1,200,000 BTUs of total energy. (our baseline reference)
If you had a 10 gallon tank of E10 (10% ethanol), it would be holding 1,155,000 BTUs of energy. (about 4% less energy by total volume)
If you had a 10 gallon tank of E88 (let's assume 15% ethanol), it would be holding 1,135,500 BTUs of energy. (about 6% less energy by total volume).
If you had a 10 gallon tank of E85 (85% ethanol), it would hold 840,000 BTUs of energy. (about 30% less energy by total volume).
If you had a 10 gallon tank of pure ethanol, it would hold 750,000 BTUs of energy. (about 37% less energy by total volume).

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

 

[kschachn]

Yes, it is not 10% for E10. That makes no sense, EtOH does have a significant BTU value.

 

[Hall]

At Sheetz it's...

I don't remember the exact colors but they make it very noticeable with what color is for what fuel type. Caseys does the same.

 

[Speedy3861]

Actually, I keep records for every fill-up, about 2 years ago had easy access to a Gulf station that had ethanol-free 87 that I used in my lawnmower, ran several tanks through my 19 Civic until the tank was largely Gulf and took a 100 mile highway trip using it. Reverted to my usual Shell 87 w/ethanol and again too the same trip under virtually identical conditions (traffic/temperature etc). Admittedly, a "butt-dyno" type test, but the Gulf was about 3.2 mpg better (Civic averages in the mid-upper 30's highway) of course this was just curiosity. In reality, the ethanol-free Gulf was almost. 50 cents/gallon more, so no real advantage over the Shell and not Toptier. I find the 88 octane deceptive in that, unless uou read carefully, you can assume you're getting something better for less, which we know, is illogical. I'm 76 and I remember whenever ethanol hit the market and leaded gas went away, gas mileage did take a real hit.

 

[kschachn]

The only way the octane reading is deceptive is if the actual value is lower than the published value. It means nothing and it does not imply anything in regards to energy density nor mileage nor anything else. Only in the resistance to pre-ignition.

And as for your ad hoc fuel economy measurements measuring the singular variable of the ethanol content, well….

 

[Thermo1223]

I thought E85 was required to be at least E70 which is typically winter blend. I will say I did put E85 in my truck in winter and it almost didn't start after sitting out in -20F. I'm glad I had a good battery, because I could have seen how that would've run out trying to fire. It was a lot of cranking. I didn't run it anymore during the winter after that.

Ethanol doesn't like to "ignite" in the dead cold of winter. Flex Fuel Caravan was similar when running E85 in the winter months. Took a good 3-5 longer to actually start hence why they never sell pure ethanol. They need a little bit of gasoline to move it along when cold.

 

[Rmay635703]

Ethanol doesn't like to "ignite" in the dead cold of winter. Flex Fuel Caravan was similar when running E85 in the winter months. Took a good 3-5 longer to actually start hence why they never sell pure ethanol. They need a little bit of gasoline to move it along when cold.

In Brazil running e96 hydrous they just included a little tank for ether or gasoline.

The cars actually started easier than on pure gas with ether injection

 

[Torrid]

In Brazil running e96 hydrous they just included a little tank for ether or gasoline.

The cars actually started easier than on pure gas with ether injection

Oh I would think so. Ether is potent stuff. Even so with ethanol the only problem was initial start in extreme cold. It was fine once running. I never noticed a difference other than lower fuel economy in warmer weather.