Gasoline vs E10

[TTown]

I was just curious, and with respect to a Mustang GT, is regular 91 octane gasoline better / worse / no different for ones car vs 91 octane E10 gasoline? What might be the differences, if any? Would one theoretically keep the engine cleaner, get better gas mileage, etc.?

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[TTown]

A couple things I read suggested regular gas might allow for slightly better gas mileage. Also, I read this (maybe a non-issue on today's cars): "The danger that we do hear about is that alcohol is a water based fuel so it does allow moisture into the fuel lines so we’ve heard reports about corrosion and rust in the fuel systems of those older vehicles because they’re not made for that.”

 

[Timeless]

All things being equal 93 octane is 93 octane in terms of performance and timing.

10% ethanol will deliver slightly worse gas mileage and ethanol is not good for storage although at 10% I cannot imagine it being an issue.

 

[JCFoster]

It was more important in older vehicles that weren’t designed for it and lawn mowers etc. On my older vehicles I got about 2 mpg better fuel mileage. On the newer ones I don’t bother with buying it. I’ve heard some newer vehicles do still get around 2 mpg better. The down side is they sell non-ethanol for more and for my area it comes from ConocoPhillips which I don’t know if they put additives in it like name brands do. I still buy it for my beater ‘99 Rodeo and my lawn mower and usual treatment of seafoam.

 

[Shifting_Gears]

Most new vehicles are built for up to an E15 mixture, with some being E85 capable. In the southeast at least almost all stations carry an E10 blend. It’s OK for older cars as well, as it’s a low ethanol content but technically it will be harder on ethanol intolerant parts.

As mentioned, an ethanol blended fuel still meets the advertised octane rating. Ethanol is substituted in regular gasoline because of its high octane rating and the fact its less expensive than pure gasoline. So by blending 10% into regular gasoline companies are able to achieve their octane ratings at a reduced expense versus using pure gasoline.

 

[nastang87xx]

I believe our cars are rated up to E20 if I remember right. And there's nothing wrong with storing a car with E10 in it. Otherwise the car wouldn't be rated for E15 or E20 or whatever it is.

 

[rich67]

When putting car in storage use Stabil.. works great;

 

[bootlegger]

When putting car in storage use Stabil.. works great;

It's all solvent.

 

[bootlegger]

The energy density is higher in straight gas, but I doubt you could tell the mpg difference given the many environmental variables. Storage stability is about the same in both. Modern E10 and E0 is very stable, even if you store the car for a year. The only reason to run straight gas, is if you have an older vehicle, boat with fuel that isn't burned quickly, or small engines which could see daily large temperature fluctuations for months. Older vehicles don't have solvent tolerant seals, so E10 could destroy them. This isn't really much of an issue in anything built within the last few decades. Boats tend to see a lot of moisture intrusion into the fuel tank, and since ethanol has a higher affinity for water than gasoline, this can lead to phase separation. In small equipment, you can also get phase separation do to temp fluctuation causing condensation in the tank.
The key thing to remember, is fill your tank up to full if storing.

 

[Hack]

Storage stability is about the same in both. Modern E10 and E0 is very stable, even if you store the car for a year.

I thought you were a fuel expert. This statement really makes me wonder, though. Modern ethanol blends are legendary for their extremely short storage life.

Maybe there's something I'm missing here and you can elaborate why lots of people have problems with storing vehicles even for short times.

To the OP, one possible advantage of 10% ethanol for extremely cold temperatures is that water will dissolve in alchohol, so E10 fuel is less likely to have problems freezing up.

 

[nastang87xx]

I'm sure there are other additives to help out with that. FWIW, Alex Flores (Yolodouchebag) let his S197 sit before with E85 in it for a few months and it fired up and data logged perfectly fine.

 

[Hack]

I'm sure there are other additives to help out with that. FWIW, Alex Flores (Yolodouchebag) let his S197 sit before with E85 in it for a few months and it fired up and data logged perfectly fine.

Additives like Heat that people used to use to prevent gas line freezing are alcohol based.

 

[nastang87xx]

Additives like Heat that people used to use to prevent gas line freezing are alcohol based.

My blood was alcohol based this weekend...................... Stupid ass freezing temps in November.

So this is actually the first time I put Stabil in my car for storage. I figure it's not going to hurt anything so might as well. I do fill up the tank completely though. The previous two winters I just filled up the tank and everything was running fine the next Spring. Those first starts are always fun. Admittedly, I do kinda the bare minimum when putting my car into storage mode but it's kind of a don't over complicate it type of mindset.

 

[Strokerswild]

Modern ethanol blends are legendary for their extremely short storage life.

This,

I haven't used fuel with ethanol in any of my old cars or yard equipment for many years. I haven't had a curburetion issue since. Prior to making my switch, it was a crapshoot whether I was going to have issues when anything had to sit more than a month. I transition my '15 to non-oxygenated about a month before it gets parked for peace of mind since it sits for months once the snow flies.

Daily drivers get 10% (which is the norm here in MN) since they're built for it and are run every day.

 

[bootlegger]

I thought you were a fuel expert. This statement really makes me wonder, though. Modern ethanol blends are legendary for their extremely short storage life.

Maybe there's something I'm missing here and you can elaborate why lots of people have problems with storing vehicles even for short times.

To the OP, one possible advantage of 10% ethanol for extremely cold temperatures is that water will dissolve in alchohol, so E10 fuel is less likely to have problems freezing up.

No need for the passive aggressive insults, guy.
Long ago, ethanol manufacturing had no standardization, and every batch was of questionable quality. Now we have fairly strict regulations for ethanol production and EtOH/gasoline blends. Corrosion is no longer a common issue, sulfates are reduced, and oxidative stability is excellent.

People have problem storing vehicles because of phase separation. That is basically it. If your tank is vented to the atmosphere, or has a lot of head space, you are going to see condensation with temperature fluctuations. You need to fill your tank to the top, and limit temp fluctuation, if you want to store long term with E10. Most of us use garage storage, so temp fluctuation is limited. If you get phase separation, you need to suck the water layer out and do something to replace the lost octane. Those of us with E85 don't need to worry about this. E85 can hold so much water before separating, you would need to pour it in directly to see the phase dropout. I have stored my boat in the garage for 6 months at a time with E10, and had no separation or stability issues. I spent 3 years testing E10 samples around the country for storage stability and had no issues. The worst things we saw were phase separation from improper storage or sulfate buildup (more of a fuel contamination issue). Most of the sites on the internet crying about ethanol stability are trying to sell you additives or test kits. If I was storing for less than a year, and doing necessary storage prep, I would have no fear of using E10. Longer than that, and I would want to at least suck the water bottom out and replace half the fuel. If you are storing well over a year, you will likely want to drain the tank and refill before running again, even with E0.
https://www.steeltank.com/Portals/0/1_E10fuels.pdf

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