The tank says to put AKI 91 in, I put AKI 91 in. many high tuned engines I've had before, if you used regular, they were OK if you drove it like grandma, but they would definitely start to knock under high loads especially on a hot day, then retard and lose power.

 

I put 93 octane in my 2011 E350 cabriolet. It’s what Mercedes-Benz calls for and I trust their judgement. It’s my weekend car and only gets driven about 2-3000 miles a year

My new (to me) 2016 E350 sedan has a flex fuel engine. The previous owner always used E85. The car runs great and the mileage isn’t TOO bad (21 vs 28 on the highway) BUT in my area E85 is $2.00 a gallon verses $3.85 a gallon for premium so I guess it works out as a wash in the long run. When I bought it I spoke to a Mercedes-Benz technician (former student) who said “if the car is built for E85 and the mileage doesn’t drop really bad I’d use it. It’s about 100 octane and keeps the ignition system a lot cleaner than premium gas would.” He also told me that if you’re someone who doesn’t drive much and the car sits a lot that you might have problems with ethanol because it bonds with water in the tank and when it sits the ethanol separates from the water and can cause problems.

 

Your former student gave you great advice, my car runs great on E85, yes the mileage is 25-30% less, but so is the price here, so it's a wash. he was correct on everything he said except the last line, ETOH is miscable in water and under no circumstances does it separate, it takes great effort and expense to get them too separate, I build those systems for a living. Ethanol is great for all engines, keeps them clean and is high octane, where you run into problems is with older fuel systems already gummed up from gasoline only, that get cleaned by the alcohol and fuel systems with fittings not designed for ethanol that it just eats. It's relatively easy to get to 190 proof, but then you hit the azeotrope and the last 5% is hard to get out. we use Zeolite {rocks} under vacuum to get the last 5% water out, which costs more per gallon than getting to 190 in the first place.

 

I use top tier 93 almost exclusively, but I have had to fill up using 87 once or twice.. no noticeable difference in MPG or performance, no pinging, etc. Cars are able to easily adjust for this. Probably didn't make its full 302hp but doubt it is harmful.

 

"Ethanol separates from water" is total crap sentence. Whoever said this does not know anything about alcohols.

Any alcohol with the -OH part in the molecule is 100% water soluble and alcohol does not separate from water other than if you heat it (or do some other chemistry trick I'm sure). Have you ever seen a Whisky bottle in the store shelf where it has been sitting long in the back row and it has the about 45% of volume clear alcohol at the top and the dark "whisky" part at the bottom? Bet not as this would or could not happen.

Alcohol in fuel is a GOOD THING especially at winter time in winter weather states as alcohol indeed mixes with water in the fuel, that at some amounts is always present, and keeps the water from freezing in the fuel system. I think the winter grade fuel has even more alcohol in it than the normal up to 10% that it says at the pump. It just is that the sticker at the pump says "up to 10% ethanol" but there are other alcohols like methanol that can be used to control water.

There has been lots of talk about why alcohol is used in the fuel, bad talk about the government requiring it etc. I really think (don't know for sure) alcohol is used to set the octane level of the fuel. Like you say E85 is about 100 octane. Alcohol is way cheaper ingredient to use for octane purposes than the other chemicals used in non-ethanol fuel.

I have always used highest octane I can find and from the car's performance I don't think the fuel always is what it says on the pump. Modern cars run with low octane fuel even when they are made for high octane so how would you question the gas station about it? No way to do that but when you suddenly feel your car is not as strong and the fuel mileage drops 10-15% it points to the fuel octane being less than advertised at the pump.

I also now drive the 2013 S550 with the 278 engine that is direct injection. As the fuel is introduced in the cylinder at the time it needs to burn then the octane rating should be lowered for easier burning of the fuel. I have not tried this yet but at my next fill-up I will try this as it might even improve the gas mileage as if lower octane fuel burns easier/more completely then less fuel should be needed. Fuel has the same amount of energy in it regardless of octane rating other than more alcohol lowers energy, which should also improve MPG with lower octane fuel as higher octane fuel has slightly more ethanol in it.

I really think alcohol is used for octane reasons in the fuel. Someone that knows better please correct me.

 

You are correct, under most conditions, cold weather starts or 3/4 to full throttle accelerations are a different story however. Yes, computer controls can retard timing to reduce pre-detonation from 87 octane fuels, but not eliminate it. That said, if these cars can run on E-85, the occasional leisurely drive on regular probably won't matter much. I don't know as I only had to use regular one time and that was 16 years ago on a coast to coast all highway road trip in my '03 S500. I also only used E-85 twice in my flex-fuel 212.

 

I suppose it depends on who you talk to if ethanol is a good thing or not. In my opinion, corn is food not fuel. Unfortunately, the farming lobby is such that laws are passed that guarantee farmers a captive audience. Fortunately, there's at least 3 gas stations in my immediate area that have the blue hose blissfully ethanol free fuel.
Here's some light reading (I highlighted some parts in bold):
https://www.bellperformance.com/blog...20much%20water.

 

The alcohol was originally added as an 'oxygenation' agent, which helps carbureted cars with catalytic converters burn a little cleaner, also its a 'renewable' fuel for some values of renewable. mostly its a perk for the industrial corn industry.

indeed it does have higher octane rating (which really means slower burning), but less energy than regular gas. of course, if our gasoline was pure Iso-Octane (C8H18), it would be 100 octane, and not need *any* additives, but instead our gas is a mix of different isomers of various weights of hydrocarbons, predominantly alkanes.

 

No, no no and no.
!] corn for ethanol is not something you or livestock would want to eat, yes, it is a Specific variety usually planted were sweet corn and feed corn won't grow well.A farmer makes more money on sweet and feed corn per acre by a lot.
2] natural aspiration of your gas tank or a 300k gallon tank occurs as the daily temperature rises and falls, liquid expands in the heat of the day and contracts in the cool of the night, bringing in air of relative humidity, if it's raining this can be 90%. in the cooling process this condenses on the tank walls and is adsorbed into the tank volume, ethanol is better at this than gasoline, ETOH absorbs it and gasoline rises above it as it settles to the bottom of the tank
3] Yes you can Phase separate ethanol with water, to do so you would need a large amount of water, more than would ever get into your tank, like two gallons or so, same for the big ones, that's why everyone uses nitrogen blankets to alleviate this.At the station gas is stored below ground at an almost constant temperature or very slow fluctuation which almost eliminates this issue.
4]ETOH cleans your fuel system and keeps it clean, it also adds octane to otherwise low octane fuel, yes it contains less BTU's of energy, but costs half as much to produce. As you go up a distillation column you produce less BTU's, diesel, kerosene, White gas, Regular then premium, in that order. There are pull-offs for fusel oils as well, like isobutane and others as LCG mentioned.

You can like ethanol or dislike it, it's politics and rumors, everyone is entitled to their opinion, I actually believe we should end blending too and just use ethanol, imagine no catalytic converters, no radiators, no 2k psi fuel pumps, no spark plugs or wires, coils and engines lasting 500k miles easy. In the mean time, those of us in the industry appreciate you paying extra for straight RBOB!
Just for fun, maybe a quick read on the P-47 Thunderbolt and what made it viable and fast at altitude might be of some interest, also used on the B-29?

 

[QUOTE=pierrejoliat;8332092]. . . yes it contains less BTU's of energy, but costs half as much to produce.[QUOTE]

Does it actually cost half as much to produce ethanol? It has always been my understanding that the price of E85 is kept "artificially" low because of all the federal subsidies that are pumped into the industry. And without these subsidies, ethanol would not begin to be competitive. Do you know if there is any truth to this?

 

huh? ethanol requires spark ignition in a piston combustion engine, its not a diesel fuel.

and it generates heat, the engine will need cooling, so you need a radiator. and with enough compression to generate adequate power, it creates nitrous oxides that need a cat to reduce. fuel pumps? conventional manifold injection usually needs around 40 PSI, its direct cylinder injection that needs 2000 PSI, diesel direction needs even higher.

 

This "alcohol attracts water" talk is just nonsense. You can say it also "water attracts alcohol" if you like. The fact is, if water and alcohol are put in the same container they will mix very easily.
You will have water pumped in your car's fuel tank regardless if you use ethanol containing fuel or not. If you use non-ethanol fuel only you can expect issues with water corrosion and if you lived in winter weather area you would experience the worst nightmare, the fuel line froze up. And it will not thaw out before the car is put inside in temperature to melt the ice. When it is frozen adding alcohol in tank won't help.

I come from a serious winter area and remember how in winter time my father bought a 1 liter bottle of near 100% alcohol at the gas station and poured it in each time before filling up. This was absolutely necessary as without it your car would not run due to frozen fuel lines. This alcohol was treated chemically so that you would not want to drink it, the taste was so bad. Since then they have started making winter grade fuels so that it is not necessary to add alcohol anymore by yourself.

There is a lot of talk like yours that alcohol is made for fuel use only because the government does "this or that". I bet the oil industry would still keep adding ethanol in fuel for octane reasons even if the government stopped doing "this or that". It is the cheapest ingredient for octane boost there is.

 

before they mandated alcohol, they were using MTBE, which is nasty toxic stuff that they normally just flare off, so it was practically free.

 

You might make out in the winter on E85. I believe the limit is that it can't be more than 85% ethanol, but it could be less. And if it's less, you're getting more gas than ethanol which I think is why some people report better than expected gas mileage with E85. In cold weather, they up the mix of gas as ethanol is harder to run in the cold.

 

[QUOTE=Bhopkins;8332203][QUOTE=pierrejoliat;8332092]. . . yes it contains less BTU's of energy, but costs half as much to produce.Most of the subsidies are gone years ago, if you want to see the pricing real-time look to CBOT or Chicago board of trade, currently there is a small producer credit, but Cargill, Valero are huge, even Pacific ethanol at 150MGPY doesn't qualify any longer.

 

no, no and no.
An engine built for ethanol only does not require any of the things I mentioned and it will run in a diesel at E85 levels all day long, ethanol burns at a much lower temperature than gasoline so a heater core for your comfort and air cooling is more than enough. Cold start glow plugs are enough to get it started with lower compression than diesel, like 14-1. My friend in Manteca's tractor has been running on ETOH for at least ten years, no issues so far, he does add diesel to keep up the lubricity. The ETOH NOx is 40% less than gasoline with a converter, so no converter needed,

 

[QUOTE=pierrejoliat;8332247][QUOTE=Bhopkins;8332203]Subsidies still very much exist.
How much does it cost to produce a gallon of ethanol vs a gallon of gasoline? Don't be afraid to show your sources.

Do boats use ethanol laced fuel? Why or why not?

 

[QUOTE=rapidoxidation;8332265][QUOTE=pierrejoliat;8332247]I own an ethanol plant and a large holding in three others, that's my source. I produce 10 MGY of ETOH in my facility, that's my background. I know exactly when I lost my small producers credit, as it directly reduced my profit margin in 2010. I receive NO government subsidy currently, I also fund research projects at Carnegie Melon, Texas A&M and Hiram College, we have four small diesels and one large diesel running on ethanol only for years now and quite a few other test projects. YOU?

 

[QUOTE=pierrejoliat;8332270][QUOTE=rapidoxidation;8332265]What about me? I have no vested interest in the continued production of a fuel that takes (how much?) energy to produce. Granted, it has stopped the use of MTBE and that's great.
We can do better than using our open spaces to grow fuel.
How about this: You do you. I won't. We can disagree on this.

 

Stop by sometime, I'll show you how I do it with zero corn, zero farmland and a cost to produce around 60 cents a gallon and maybe a little enlightenment!

 

[QUOTE=pierrejoliat;8332270][QUOTE=rapidoxidation;8332265]And in Brazil they have most all cars running with ethanol only, no gasoline in it for tens of years already.

 

[QUOTE=Arrie;8332308][QUOTE=pierrejoliat;8332270]Brazil is mostly a warm climate. Ethanol isn't that great for starting cars in the winter which is why we have E85. Their cost of oil, cost of labor are probably completely different from the US so it may make sense for them.

 

Um, fuel (crude oil) is also made from "food"... dead animal and plant matter. The only difference is 30-70 million years. Just sayin'...

 

NOw thats funny!

All this alcohol talk makes me want a Scotch on the rocks