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harvey lee

Unleaded vs Ethanol

19 posts in this topic

I ran a test this weekend on the two fuels to see just what the savings ccould be. I tested a 2006 Chev 1500 4x4 with a 5.3. All driving was done at 59 mph and the trip was 325 miles one way on unleaded and the return trip on ethanol. The wind was the same both trips and same outside temps.

Unleaded

20.4 mpg @ 59.0 mph on cruise

$3.69 per gallon

Ethanol

18.0 mpg @ 59.0 mph on cruise

$2.70 per gallon

Seems by my math that the unleaded did approx 10% better on mileage. But, figuring the added cost per gallon, I can run Ethanol at a much less cost per mile if the ethanol is price approx .37 per gallon or less. At ethanol under $3.00, which I saw at many different gas stations, one can run this flex fuel and save.

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10-20% difference is what you will normally see. To give e85 the true test you need to run it for 3 tanks so the computer in your truck learns the new fuel. The last thing you want to do is continue to switch back and forth between the two. It wont hurt anything, but you will get worse milage and most likely a check engine light coming on. It is best to stay with one or the other. My father in laws truck gets the same milage per gallon using e85 as he does with unleaded, not typical though!

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Tom you may get better, or worse, but on the 3rd tank the computer will have had enough time to relearn the change. Is your truck a flex fuel truck?

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I didn't think it would take three tanks to learn. I thought automotive computers just look a real time data and make adjustments at that time. Do the Chevrolet computers have a memory?

I may be incorrect with this but I thought that the computers just calculated real time unless in closed loop so it shouldn't matter what fuel you dump in but what the O2 sensors and map or mass air flow sensor tells the ECM where to set fuel trim. Please correct me if I am wrong I have been stuck in Honda land for a long time.

BTW Honda does not do flex-fuel all I know is if someone fills up in Iowa and unwittingly fills up with ethanol and comes to our dealership with a CEL it will most likely be a lean code because honda has not set the parameters in their ecm's to counteract the extra oxygen in the ethanol and the injectors can't keep up most likely the ecm's fault. So that said are the Chevrolet ECM'S adaptive or are they just running on primarily parameters set by the manufacturer? I like to keep up so I would like to know.

Thanks EP

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The computers have a short term memory, and a long term memory. The short term reacts immediatly and change fuel trims to what the conditions are, load, engine temp, ambient temp, baro, throttle position. They also have a long term memory which learns drivers habbits, and fuel octane, ect.. such as do you hammer it on take offs, drive slow, drive like an 80yr woman, or a 17yr male! It then uses that data to calculate timing and injector pulse width. Which in term can effect fuel economy.

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Ya, a big no no to switch back and forth. I have seen this cause some failures of sensors and I thought a fuel pump in a Ford Tauras once (that might have been a person running E-85 in a non E-85 veh. though), for sure poor fuel econ and check eng. lights. It is such a shock to the system like what 4.W.E. said. I also thought it was a good idea to blend tanks when switching 20%/80%, 50%/50%, 80%/20%. I could be wrong on this, but I thought it helped the P.C.M. switch easier.

Also a big note, to run E-85, you are supposed to have synthetic oil in the engine. Check you owners manual for more info or call your dealer and ask about the added maintenance items needed when running E-85. What I was told is the ethanol mixes with the conventional oil, creates a chemical reaction over time and eats at internal eng. seals. Synthetics do not cause this to occur.

A couple years back we did a comparison at the dealer I worked at. With the added maintenance cost’s, drop in fuel econ, the price of regular gas verses E-85 at that time and it worked out about the same.

If anyone has any questions further, contact your dealer’s service department and they will give you the run down.

Good luck!

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I have synthetic in the motor but I can only find ethanol low enough in a few locations. So, with that being the case, I will need to just run unleaded all the time. My local station charges way to much for the ethanol to make it even close to worth while. I cannot understand why some of the same brand stations that carry ethanol are 60-70 cents cheaper than the others of the same brand.

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Shack the oils that are made now wont react differently. In 98 the Rangers and a few others needed to run special oil when using e85, now they all use the same oil.

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How long you been out of this? Synthetic oil was for the first flex fuel Taurus in 1994. When they were reintroduced into production there were no oil differences. You have seen one fuel pump bad on a Taurus due to E85, thats a miracle. I was on the E85 advisory board in the mid 90's representing Ford Motor with engineers from Detroit, we were working with the Minnesota Chapter of the American Lung Association, the early driving force behind E85. One of the biggest concerns with getting E85 into more than the one station that sold it in the whole state at that time was the repeat failure of fuel pumps. Changes were made, but not perfected, E85 continues to be the #1 cause of premature fuel pump failure. 10% ethanol has a similar negative effect on fuel pumps, I put in as many as 8 on a 90 degree day 2 summers ago. Something must have changed in the year I've been out of the business, E85 vs. reg unleaded was only capable of 40% of the mileage then.

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I was going to mention the oil situation as well. It still would not hurt to check in the owners manual to see what the manufacturer recommends. Especially if the factory warranty is in play.

Honestly I think it is to soon to know what the long term average will be with the E-85 and vehicle integrity. Meaning will the mechanics and materials hold up long term? If it does great! If it doesn't than was it really worth it?

Fuel pump failures on hot days have been have been happening for as long as there have been "domestic" vehicles with electric pumps in the tank! by the way my record is 4 in one day with either 8 or 10 for that week (one hot week in august a few years back).

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I cannot understand why some of the same brand stations that carry ethanol are 60-70 cents cheaper than the others of the same brand.

Much of that depends on ownership. Many privat and co-op stations set their own price while chain run stations have prices set for them.

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Shack the oils that are made now wont react differently. In 98 the Rangers and a few others needed to run special oil when using e85, now they all use the same oil.

I should have been a little more clear on this. Fords 5w-20 blend is ok, others are not (I am not sure about Chevy).

I got this from a e85fuel web page:

Quote:
Why do ethanol vehicles require a certain type of motor oil? Does this refer to dedicated ethanol vehicles only?

Response:

Ford no longer requires the use of synthetic oil in the flexible fuel (FFV) Taurus when operated on either E85 or unleaded gasoline.

To the best of our knowledge, Chrysler does still require a special FFV engine oil. The concern here is that uncombusted ethanol (especially during rich cold start conditions) may migrate past the piston ring resulting in cylinder wall washing which reduces cylinder wall lubrication and could run down into the crankcase, diluting the engine oil.

While such occurrences are unlikely, the special engine oil adds an additional degree of protection until more field experience can be accumulated. These requirements apply to Chrysler FFV minivans if they are to be operated full- or part-time on E85.

I still would contact your dealer if you are under warr... They might even have a class on E-85 for new owners or some good reading.

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Good point shack, I was thinking because Fords switched I "assumed" they all would have. I see the newer Chryslers now recommend 5w20 in theres as well, either ff or not.

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I found this interesting, a few years ago I was picking up a boat in Florida for transport back to the Great Lakes. I was there about a week waiting on the boat to be readied for the trip and it was upper 90's to 100+ each day. I got to know a few of the marina employees and boat owners, we got to talking about heats effect on their vehicles. I figured with that kind of heat, fuel pumps would almost be a maintenence item, changed as frequently as oil. But to my suprise, most had never had a failure. The biggest difference we could come up with is at that time they had no ethanol in there fuel, Minnesota did.

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Thats interesting Capt! I personally am leaning towards lack of filter changes. I just did one on an Astro van when I opened the can on the pump I was not surprised to see the commutator worn out especially since the filter was plugged solid.

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Has anyone tested the difference while pulling or city driving to me that would be more of a test rather than a constant speed.

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If I remember right there were a rash of fuel pump and filter issues with older cars when ethanol was first added to the gasoline. It did a great job cleaning the whole fuel system of years of sludge.

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