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Locally regular 87 octane gas contains up to 10% ethanol blend while premium 91+ octane does not. I know the Gen2 runs on 87 octane but would using premium offer any advantage considering you're not getting ethanol blended gas?
 

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Ethanol in gasoline allows it to degrade faster.
And ethanol has less energy per gallon than gasoline.
I'd run ethanol-free if you have a choice, regardless of octane.
You stand less chance of stale fuel problems, and your fuel tank will store more miles of fuel.
 

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Running premium fuel in a vehicle that doesn't need it, isn't a good idea and I'm not talking about wasted money.
 

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10% Ethanol is no problem, the tank is water tight and pressurized, and the car is designed to run with it. Buy whatever is cheapest. I do like Top Tier gas as it is required to meet the requirements set by GM and others for all fuel grades, not just premium.
 

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Wouldn't the cars computer automatically adjust for it?
Short answer, running Premium in a car that doesn't need it can lead to carbon build-up in the cylinders.

Long answer:

Since the higher octane fuels burn slower, you have to advance the spark to make sure they completely burn. This is called "ignition advance". The spark-plugs need to fire sooner in the compression-stroke.

Here' the problem...

1: If your car isn't designed for higher-octane fuels, you're actually going to be hurting power using higher octane gasses since the slower burning mixture doesn't have time to burn completely and can actually work against the power-stroke in the following exhaust stroke.

2: The unspent gasses that don't get burned translate directly to "carbon buildup" on your sparkplugs, making them go bad sooner. The unspent gasses carbonize, turning into black powder, which then coats your spark-plugs, dirties your valves, and your piston rings. Over time this (excessive carbon deposits) can lead to damaged spark-plugs, compression losses from cylinder wall wear causing your engine to burn oil and loose power, etc...

So using the wrong octane rating is not a good idea in your average daily-driver. Your engine will last longer and have more power if you use the recommended octane.
Although GM direct injection engines don't seem to have much of a problem with carbon buildup, other makes do, so to be safe I wouldn't run premium.

For more info on direct injection carbon buildup: http://www.autoguide.com/auto-news/2015/01/is-carbon-buildup-a-problem-with-direct-injection-engines-.html
 

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Locally regular 87 octane gas contains up to 10% ethanol blend while premium 91+ octane does not. I know the Gen2 runs on 87 octane but would using premium offer any advantage considering you're not getting ethanol blended gas?
I'd guess if the regular has ethanol, the premium does too. Using premium in a engine designed for regular certainly lets you spend more on fuel. Other than that, who knows? Non-ethanol gas usually has more energy and might give a little better mileage.
 

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Locally regular 87 octane gas contains up to 10% ethanol blend while premium 91+ octane does not. I know the Gen2 runs on 87 octane but would using premium offer any advantage considering you're not getting ethanol blended gas?
As with any vehicle, why run a higher octane than the vehicle is tuned to use?
Money wasted.
 

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Locally regular 87 octane gas contains up to 10% ethanol blend while premium 91+ octane does not. I know the Gen2 runs on 87 octane but would using premium offer any advantage considering you're not getting ethanol blended gas?
Note not all premium gas is ethanol free. Details and locations at the link below:
http://www.pure-gas.org/

As others pointed out the Gen II Volt was designed to run on regular 87 octane gas. So it will run best on regular gas. There is absolutely no benefit to running premium. Though there are some benefits to running ethanol free gas. And there are places where you can find ethanol free regular gas in Ontario.
 

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Discussion Starter #11
Which brings me back to my original thoughts. Do the benefits of ethanol free gas outweigh the fact that the Volt Gen2 doesn't necessarily need premium fuel.
 

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Running premium fuel in a vehicle that doesn't need it, isn't a good idea and I'm not talking about wasted money.
Short answer, running Premium in a car that doesn't need it can lead to carbon build-up in the cylinders.

Long answer:

Although GM direct injection engines don't seem to have much of a problem with carbon buildup, other makes do, so to be safe I wouldn't run premium.

For more info on direct injection carbon buildup: http://www.autoguide.com/auto-news/2015/01/is-carbon-buildup-a-problem-with-direct-injection-engines-.html
I see zero substantiation in that link for your assertion that higher octane fuel causes carbon build up in DI engines. Could you please provide some (any) credible source/evidence that speaks specifically to that assertion? Otherwise, it just sounds like baseless hearsay.


As to the question of running premium vs regular, it clearly isn't "necessary" or the manufacturer would specify it, and it definitely costs more, but that's not to say it isn't without some possible benefits such as being 100% gasoline and potentially better and/or higher detergent/additive content. This varies greatly depending on brand and locality, so it isn't always substantial, but then the price differential isn't always all that substantial either (just 15-20 cents here), so opting for the up-charge in a car that sees little fuel usage isn't altogether unreasonable on a cost-to-benefit scale. Regardless of which grade is used though, it should always be top-tier rated.

In my case, the ICE is only ever used for some minor range extension about once a month. Under these conditions, a tank of fuel will literally last over a year, so my concern is to buy the highest quality of fuel with the least least possible degradation rate. For that reason, I use premium, and I generally only keep 1/3 of a tank at a time in the car. That way, I can refresh the gas with a more significant dilution rate when adding just a gallon or so every quarter.

All that being said, if I were taking a trip in the car and knew that I would be running through a tankful of gas, I would not hesitate to use a top-tier regular grade. Upon return home, and the resumption of normal fuel usage, I would switch back to premium.
 

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The only advantage of ethanol-free gasoline is more energy per gallon, so probably slightly better mpg. Ethanol has a lower energy content per gallon. It is about 70% of pure gasoline (E85 is about 73% of pure gasoline) so 10% ethanol mixed with 90% gas will have about 3% less energy than 100% gasoline, with a resulting mpg decrease.

http://www.energyalmanac.ca.gov/transportation/gge.html.
 

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Something to note. Alcohol always has water and available oxygen in it. It can never be removed. Both of these degrade metals and polymers far faster than hydrocarbons do. Water will not dissolve in pure gasoline which retards the growth of algae in the fuel.

Ethanol risks are known and are engineered for. But there is only so much you can do. Given the choice, run hydrocarbons, as it is always the least risk.

But yes, any octane higher than is required to reduce detonation to acceptable levels (a small amount of knock is OK) is a waste of money. It will not improve engine operation.
 

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No offense but why not just test it?

If I read the thread here it sounds like if he puts premium in his car it will be an abomination to God and one million angels will vomit in disgust.

Reality is it doesn't really make a diff either way, his engine won't be damaged but he likely won't gain anything.

If he wants to know, instead of pretending to know what will happen just test the crap over a daily drive scenario over several tanks of fuel.

Compare the premium to the regular (assuming your outside temperatures are the same)

You might find it makes a small difference to fuel economy, you might find it doesn't.

For me I've found that e20 ethanol has minimal affect on fuel economy in warm weather, I wouldn't have known this if I wouldn't have tried it.
 

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No offense but why not just test it?

If I read the thread here it sounds like if he puts premium in his car it will be an abomination to God and one million angels will vomit in disgust.

Reality is it doesn't really make a diff either way, his engine won't be damaged but he likely won't gain anything.

If he wants to know, instead of pretending to know what will happen just test the crap over a daily drive scenario over several tanks of fuel.

Compare the premium to the regular (assuming your outside temperatures are the same)

You might find it makes a small difference to fuel economy, you might find it doesn't.

For me I've found that e20 ethanol has minimal affect on fuel economy in warm weather, I wouldn't have known this if I wouldn't have tried it.
I don't think it's so horrible if the OP wants to use premium. I just think it's a waste of money and provides little or no benefit. The car is designed to handle ageing fuel and low engine duty cycles. If one wants to experiment, I think there's little chance of causing harm. I also think the differences are probably going to be down in the noise of the data. You can probably do two runs changing nothing and get enough difference to make you wonder why.

Gen 1, lots of drivers wanted to use regular even though premium was specified by Chevy. Now Gen 2 gets better mileage and runs on regular so we have drivers trying to rationalize running on premium. Sheesh.
 

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Gen 1, lots of drivers wanted to use regular even though premium was specified by Chevy. Now Gen 2 gets better mileage and runs on regular so we have drivers trying to rationalize running on premium. Sheesh.
Maybe everyone should swap cars. :p
 

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No offense but why not just test it?

If I read the thread here it sounds like if he puts premium in his car it will be an abomination to God and one million angels will vomit in disgust.

Reality is it doesn't really make a diff either way, his engine won't be damaged but he likely won't gain anything.

If he wants to know, instead of pretending to know what will happen just test the crap over a daily drive scenario over several tanks of fuel.

Compare the premium to the regular (assuming your outside temperatures are the same)

You might find it makes a small difference to fuel economy, you might find it doesn't.

For me I've found that e20 ethanol has minimal affect on fuel economy in warm weather, I wouldn't have known this if I wouldn't have tried it.
+1
I don't think it's so horrible if the OP wants to use premium. I just think it's a waste of money and provides little or no benefit. The car is designed to handle ageing fuel and low engine duty cycles. If one wants to experiment, I think there's little chance of causing harm. I also think the differences are probably going to be down in the noise of the data. You can probably do two runs changing nothing and get enough difference to make you wonder why.

Gen 1, lots of drivers wanted to use regular even though premium was specified by Chevy. Now Gen 2 gets better mileage and runs on regular so we have drivers trying to rationalize running on premium. Sheesh.
Have you tried? Or seen engineering data testing it? If no, you can't really claim it will do nothing, nor that it will be a pure waste of money with no benefit.
Many engines are designed to run on premium, but down-spec'd for regular. By running premium you do actually get a noticeable difference in performance and efficiency. But they want to be able to sell it as running regular as premium is a turn-off to many buyers.

Now, whether this volt engine is one of those, I don't know. But until someone tests, neither do you!

To OP, I say, go for it. Give it a try.
Try running premium only for a month and compare how it goes on easily repeatable trips (e.g. 100km steady state at same temp
 
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