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Discussion Starter · #1 ·
I got my 2015 Volt from the dealer with 3/4 of a tank full. I have no idea if the fuel is 91 AKI or not. I don't trust the flunkies at the dealership to realize that it requires premium.

I've heard that the Volt can detect the lower grade fuel and adjust the timing, but is there any way for me to tell if it has detected low grade fuel?

If it does have low grade fuel in it, what can I do? I've heard it's not recommended to drain the fuel tank, but I don't want to burn through a bunch of extra fuel just to flush it out.
 

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Don't worry about it. 3/4 tank won't hurt. When you refill, you'll be able to make sure the grade you use.
 

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Keep in mind the primary use of the gas engine in the Gen 1 Volt is to operate as a generator. When the car is moving down the road at low to moderate speeds using the range extender, the engine is contributing no propulsion torque at all while cranking out gas-generated electricity to fuel the motor. One might say the limited range of operating demands placed on the engine optimizes the benefits of using premium gas in the Gen 1 Volt, without necessarily requiring its use.
 

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Depending on the octanes sold in your local area, 91 may be top-grade, or it may be a mix. If you are worried about it, I would burn off a few gallons, then top it off with the highest octane available in your area. If the tank is low octane this will raise the octane some without having to burn through a full tank
 

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Keep in mind the primary use of the gas engine in the Gen 1 Volt is to operate as a generator. When the car is moving down the road at low to moderate speeds using the range extender, the engine is contributing no propulsion torque at all while cranking out gas-generated electricity to fuel the motor. One might say the limited range of operating demands placed on the engine optimizes the benefits of using premium gas in the Gen 1 Volt, without necessarily requiring its use.
Gen1 ICE contributes direct mechanical propulsion above 36mph unless you are demanding a ton of torque.

OP, my dealer gave me a full tank of 87 octane at delivery on my brand new Volt; I know because I asked them. I also asked why they didn't follow the manual and put in premium and they shrugged, they seemed unaware. Grrr. But yeah, one tank won't hurt you. I think I burned off a few gallons and put in premium, hoping the mix would raise the average a bit, can't hurt to do that.
 

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How much gas do you think you'll use on a monthly basis. I'd burn off what you have then add in some fresh premium but only the amount you'll need for a month or two of driving.

After I got hit with the FMM last June where I was forced to burn off over half a tank of gas that was in the car when I bought it in Aug 16 I now only carry about 2 gallons of gas around. I can always add more if I'm taking a trip that exceeds the battery and 2 gallons of gas range.
 

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Top it off with the highest grade available in your area and don't worry about it. Running 87 continuously isn't good for the engine, but one tank won't cause major trouble.
 

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One tank isn't gong to hurt anything. Like others have said, add some high octane fuel or octane booster if it will keep you from worrying about it. I can't think of a quick/easy was to test the octane of the fuel already in the tank.
 
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Discussion Starter · #11 ·
Gen1 ICE contributes direct mechanical propulsion above 36mph unless you are demanding a ton of torque.
I could be wrong but I seem to remember in the GM video on YouTube about how the propulsion of the Volt works that at a certain speed the small motor takes over from the large motor as it is more efficient than having the large motor spinning fast. When the gas engine is being used to generate electricity by turning the small motor at a certain speed the engine/small motor is directly clutched for a direct connection as that is more efficient and this happens at highway speeds (60/65/70 mph?) kind of like an ICE engine operating in overdrive. Anybody recently review that video?
 

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If you need peace of mind, then go to your local auto parts store and get some octane booster as stated here in a previous post.
 

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Given that the owner doesn't know what octane is in the tank, I don't think it is necessarily a good idea to add octane booster. That might result in too high octane, which is not a good thing either. It can make ignition difficult and cause rough running. These cars run fine on 87. Lots of G1 owners burn only that. I think the manufacturer's recommendation for premium is more about ensuring adequate octane after a year of storage in the tank. Best course of action is to just forget about it. Burn it off in normal use when you are beyond electric range. That usually takes a couple of months or less for most owners.
 
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Discussion Starter · #14 ·
Don't worry about it. It will burn it just fine. I don't think the reason they went to premium had anything to do with length of time the gas might be in the fuel tank even though that might help. Regular fuel in the tank of Gen 2's is in there for the same length of time. It had to do with the tune of the engine they had available to get the maximum EPA figures. The Gen 2 engine was tuned for regular and they were able to get better figures with direct injection and whatever else they did realizing that being able claim regular use was another feather in the cap.
 

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Given that the owner doesn't know what octane is in the tank, I don't think it is necessarily a good idea to add octane booster. That might result in too high octane, which is not a good thing either. It can make ignition difficult and cause rough running. These cars run fine on 87. Lots of G1 owners burn only that. I think the manufacturer's recommendation for premium is more about ensuring adequate octane after a year of storage in the tank. Best course of action is to just forget about it. Burn it off in normal use when you are beyond electric range. That usually takes a couple of months or less for most owners.
I don't think the typical over the counter octane booster is enough to make ignition difficult. There's some evidence that the knock sensor and ignition retard are pretty busy with 87 octane fuel. It's probably more than just fuel shelf life.
 

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I got my 2015 Volt from the dealer with 3/4 of a tank full. I have no idea if the fuel is 91 AKI or not. I don't trust the flunkies at the dealership to realize that it requires premium.

I've heard that the Volt can detect the lower grade fuel and adjust the timing, but is there any way for me to tell if it has detected low grade fuel?

If it does have low grade fuel in it, what can I do? I've heard it's not recommended to drain the fuel tank, but I don't want to burn through a bunch of extra fuel just to flush it out.
Maybe the Volt was purchased by the dealer with the tank 3/4 full. The previous owner could have filled the tank with premium fuel. My experience when buying my Volt new is that my salesman was responsible for filling the Volt's fuel tank as part of the new vehicle delivery process. You could contact the salesman and ask them about the fuel.
 
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Discussion Starter · #17 ·
How much gas do you think you'll use on a monthly basis. I'd burn off what you have then add in some fresh premium but only the amount you'll need for a month or two of driving.

After I got hit with the FMM last June where I was forced to burn off over half a tank of gas that was in the car when I bought it in Aug 16 I now only carry about 2 gallons of gas around. I can always add more if I'm taking a trip that exceeds the battery and 2 gallons of gas range.
I would be worried about condensation forming, every day/night cycle, because of temp differential. My plan is to keep my ELR FULL at all times to avoid water formation.:eek:
 

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Don't worry about it. It will burn it just fine. I don't think the reason they went to premium had anything to do with length of time the gas might be in the fuel tank even though that might help. Regular fuel in the tank of Gen 2's is in there for the same length of time. It had to do with the tune of the engine they had available to get the maximum EPA figures. The Gen 2 engine was tuned for regular and they were able to get better figures with direct injection and whatever else they did realizing that being able claim regular use was another feather in the cap.
Best answer in this thread. 87 octane does no harm to Gen1 Volt's engine. Premium Fuel "Requirement" was spec'd for EPA fuel economy figures. I drove my 2012 for 3 years, 42,819 total miles of which 4,957 miles were on ICE. My MPGcs was 41.28 (source: Voltstats.net).

I know most people on this board that's been running 91 octane will not be convinced - I've learned that long time ago. And it doesn't matter that I got the above info directly from a project manager at GM Advanced Powertrain Development Center (Torrance, CA) or that I worked in petroleum industry for 7+ years, 2 of which were at a Texaco refinery in Wilmington, CA where I was the crude oil buyer and gasoline blender.

One more tip - buy the least expensive gasoline you can find. Costco gasoline will work just as well as Chevron gasoline. In fact, most of Costco gasoline comes from a major refinery. They are cheaper because Costco doesn't spend MILLIONS $$$ a year on marketing mumbo jumbo that Chevron/ExxonMobil/Shell does each year. Gasoline is the most fungible commodity you can buy.
 

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Best answer in this thread. 87 octane does no harm to Gen1 Volt's engine. Premium Fuel "Requirement" was spec'd for EPA fuel economy figures. I drove my 2012 for 3 years, 42,819 total miles of which 4,957 miles were on ICE. My MPGcs was 41.28 (source: Voltstats.net).

I know most people on this board that's been running 91 octane will not be convinced - I've learned that long time ago. And it doesn't matter that I got the above info directly from a project manager at GM Advanced Powertrain Development Center (Torrance, CA) or that I worked in petroleum industry for 7+ years, 2 of which were at a Texaco refinery in Wilmington, CA where I was the crude oil buyer and gasoline blender.

One more tip - buy the least expensive gasoline you can find. Costco gasoline will work just as well as Chevron gasoline. In fact, most of Costco gasoline comes from a major refinery. They are cheaper because Costco doesn't spend MILLIONS $$$ a year on marketing mumbo jumbo that Chevron/ExxonMobil/Shell does each year. Gasoline is the most fungible commodity you can buy.
As you say, you only put 4,957 ICE miles on. I wouldn't expect damage from knock to be noticeable at that low mileage.

For those of us who have seen the knock sensor activity when running 87, it's absolutely clear that the engine requires 91 octane. Many people will get away with using 87 without a major engine failure. But, given the limited gas I use and trivial price difference between grades, I wouldn't risk it.

I do agree that Costco gasoline is excellent. They even claim it meets "top tier" requirements now, for what that's worth.

If you want to fight against wasted gas money, talk to the people using 89 octane. No car calls for that. It's wasted on cars requiring 87, and not good enough for cars requiring 91.
 
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Discussion Starter · #20 ·
If you want to fight against wasted gas money, talk to the people using 89 octane. No car calls for that. It's wasted on cars requiring 87, and not good enough for cars requiring 91.
Not true. I've used 89 octane in my '91 Integra for 27 years with over 220,000 Km on it with no problems. The only time I put 91 octane in it was when going over the mountains in particular going up the Coquihalla as the engine had to work extra hard going up "the smasher". I live by the ocean (sea level) which helps (moist air). As well although my '88 Tercel wagon 4X4 has 91 octane in the users manual, I've only ever put 87 in it. That's been going fine for 30 years and 189,000 Km and it's a third world model sold in N/A for a couple years with no FI or computer. It has never knocked. Mind you I don't floor it, just accelerate with traffic and as stated driving is at sea level with mostly cool moist sea air going through the engine so not a lot of stress on the engines.
 
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