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So my 2015 Volt, with almost 30k miles, has only used up some 20 gallons of gas.

In the last week, a message pops up again telling me that the gas is getting stale and I need to use it. I'm now thinking I will run down the gas to zero. Is this even possible? Would the Volt switch to electric once the gas is used up? Or would the car not start once there is no gas, never mind I will still have plenty of electric range?
 

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So my 2015 Volt, with almost 30k miles, has only used up some 20 gallons of gas.

In the last week, a message pops up again telling me that the gas is getting stale and I need to use it. I'm now thinking I will run down the gas to zero. Is this even possible? Would the Volt switch to electric once the gas is used up? Or would the car not start once there is no gas, never mind I will still have plenty of electric range?
You can either use up the remaining gas, when you get down to less than ~1.5 gallons you may experience reduced propulsion as the Volt is determined to conserve fuel to get you to a place where you can refuel. Alternately, if you can estimate how much old fuel remains and add an equivalent amount of fresh fuel the Volt's Fuel Management System algorithm will re-compute the average age of the fuel in the fuel tank. You won't see the FMM message again for 6 months. If you try and game the FMM by only adding a little fresh gas the Volt will sense that very little fresh fuel has been added and not re-compute the age of the fuel. If you add 1/3 fresh fuel to 2/3 old fuel the Volt will recompute the average age of the fuel as being 8 months, the FMM message will be deferred for another 4 months. If you don't regularly use gas the Owner's Manual recommends keeping the fuel tank 1/3rd full.
 

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Since you use so little, it would probably be best for you to use 100% gas and not the 10% ethanol stuff. Also, some gas treatment (Stabil, etc) would probably help

Don
 

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The Fuel Maintenance Mode (FMM) pops up when the average age of the gas in the tank is 12 months old. Once it starts, you can’t drive on grid battery power again until you do something about the age of the gas, even if your battery is fully charged.

Sure, you can choose to drive until you run out of gas, which provides the longest interval until the next FMM, ~12 months (all the gas in the tank will be fresh gas you put in the day you end the FMM). Some choose to end the FMM sooner by putting enough fresh gas into the tank to double the existing old amount, pushing the next FMM 6 months down the road. See jcanoe’s examples above... I suspect the minimum fresh gas to end the FMM will be ~1.5 gallons, the amount you need to add to an empty tank to bring the total above the "Low" gas range estimate level.

As long as you have gas in the tank, your Volt will operate "normally" during the FMM. It is helpful to have your battery charged, because if you choose to drive until you run out of gas, access to Electric Mode returns when the engine has no more fuel... and if you have no gas, you drive in Reduced Propulsion Mode until you put enough gas into the tank to bring the FMM to an end (that’s ~1.5 gallons or more). You may, of course, put more than the bare minimum into the tank...

Because of my driving habits, I’ve experienced 3 FMMs in the 6+ years I’ve been driving my 2012 Volt. Two of them I ended by running out of gas with my battery fully charged and ready for that moment...

During my third FMM, I monitored the fuel volume using the Torque Pro app, and when the app reported 0 gals, 0% gas volume as I sat on a flat parking lot near the gas pumps, I started the car and drove over to the pumps (with the engine running, apparently on the fumes), and filled the tank.

If you do run out of gas and enter Reduced Propulsion mode, when you then add gas, the computer will perform an engine test when you first turn the Volt on again to confirm things are okay, and will then switch to battery power (if you have some charge remaining), or you can use Hold Mode and use the engine (see Out of Fuel/Engine Unavailable in the manual for full explanation). When I used Torque Pro’s feedback to decide my tank was empty, after I put more gas into the tank, I turned the car on, and no self-test was performed, as if a small enough amount of gas remained in the fuel lines to avoid the self-test.
 

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Since you use so little, it would probably be best for you to use 100% gas and not the 10% ethanol stuff. Also, some gas treatment (Stabil, etc) would probably help
The Volt won't care whether you put an additive in or not. Nor will it care whether it's got ethanol-containing fuel or not. It'll still age out the gas at the same rate. This is not that problem.
 

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Since you use so little, it would probably be best for you to use 100% gas and not the 10% ethanol stuff. Also, some gas treatment (Stabil, etc) would probably help

Don
Ethanol free fuel would be ok (if you can find it in your area) as long as it meets the minimum 87 octane requirement. GM does not recommend any fuel additives be added by the owner to the Volt's fuel. Per the 2017 Volt Owner's Manual, page 231, GM recommends TOP TIER detergent gasoline. If TOP TIER Detergent Gasoline is not available GM recommends adding one bottle of GM Fuel System Treatment Cleaner to the fuel tank at every oil change; the only gasoline additive recommended by GM.
 

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Just a note, when I was in FMM last time in my 16, I let it go down to the low fuel indicator, and I actually drove it for about a half hour longer than that. I had a full battery and it never went into reduced propulsion mode.


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Just a note, when I was in FMM last time in my 16, I let it go down to the low fuel indicator, and I actually drove it for about a half hour longer than that. I had a full battery and it never went into reduced propulsion mode.


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I don't know if it would make a difference but maybe you did not experience Reduced Propulsion mode because the fuel maintenance mode (FMM) was already activated to use up much of the old fuel and continue to run until you add some fresh fuel.
 

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Just a note, when I was in FMM last time in my 16, I let it go down to the low fuel indicator, and I actually drove it for about a half hour longer than that. I had a full battery and it never went into reduced propulsion mode.
To be clear, you shouldn’t experience Reduced Propulsion Mode until you actually run out of gas.

My understanding is that the Volt should perform normally when driving in Extended Range Mode (Hold Mode, Mountain Mode, fully depleted battery) until you actually run out of gas. After you start an FMM, you don’t have access to grid battery powered driving until the FMM is ended, so you are running in Extended Range Mode (distances recorded as Gas Miles), but you still have normal performance using gas until the tank is empty.

Running out of gas will trigger Reduced Propulsion mode driving. If you still have a charge in the battery (for example, if you ran out of gas while in Hold Mode or were experiencing the FMM with a charged battery), you can drive to the gas station (or a recharging station) in Reduced Propulsion mode on battery power.

If you run out of gas after the battery is fully depleted, you’ll then have access to the usable power remaining in the battery buffer between the "switch to gas" state of charge and the "hard floor" state of charge. This is less than 1 kWh of power, but it might be enough to allow you to drive a couple of miles to the nearest refueling station.

A Reduced Propulsion episode is not triggered merely by using up enough gas to reach the point where the gas range estimate changes from a number to LOW (estimated to be when the remaining volume is ~1.3-1.5 gallons).

Note, too, that enduring an FMM means you don’t use the engine very much, so the gas range estimate that is shown just before the estimate switches to LOW may be way off. That number might have been based on occasional cold engine use mileage, and now you’re running the engine long enough to burn up the remaining 1+ gallons of gas. During my first FMM the Gas Range display switched from 27 miles to Low. I then drove 65+ miles with the ICE running before running out of gas. And I averaged 45.6 MPGcs driving 82.08 miles while using up the final 1.8 gallons of gas in the tank.
 

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To be clear, you shouldn’t experience Reduced Propulsion Mode until you actually run out of gas.

My understanding is that the Volt should perform normally when driving in Extended Range Mode (Hold Mode, Mountain Mode, fully depleted battery) until you actually run out of gas. After you start an FMM, you don’t have access to grid battery powered driving until the FMM is ended, so you are running in Extended Range Mode (distances recorded as Gas Miles), but you still have normal performance using gas until the tank is empty.

Running out of gas will trigger Reduced Propulsion mode driving. If you still have a charge in the battery (for example, if you ran out of gas while in Hold Mode or were experiencing the FMM with a charged battery), you can drive to the gas station (or a recharging station) in Reduced Propulsion mode on battery power.

If you run out of gas after the battery is fully depleted, you’ll then have access to the usable power remaining in the battery buffer between the "switch to gas" state of charge and the "hard floor" state of charge. This is less than 1 kWh of power, but it might be enough to allow you to drive a couple of miles to the nearest refueling station.

A Reduced Propulsion episode is not triggered merely by using up enough gas to reach the point where the gas range estimate changes from a number to LOW (estimated to be when the remaining volume is ~1.3-1.5 gallons).

Note, too, that enduring an FMM means you don’t use the engine very much, so the gas range estimate that is shown just before the estimate switches to LOW may be way off. That number might have been based on occasional cold engine use mileage, and now you’re running the engine long enough to burn up the remaining 1+ gallons of gas. During my first FMM the Gas Range display switched from 27 miles to Low. I then drove 65+ miles with the ICE running before running out of gas. And I averaged 45.6 MPGcs driving 82.08 miles while using up the final 1.8 gallons of gas in the tank.
Thanks for the detailed explanation.


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You can run the Volt completely dry. It will complain, but switch to electric even if depleted and go into limp mode for a mile or two.

It will complain and nag you constantly that it needs gas. It may show propulsion reduced.

https://gm-volt.com/forum/showthread.php?11942-Running-on-empty

there's a lot more detail.
Thanks also. It seems I’m always discovering things about this car, even after several years of driving it.


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I would run it near dry (0 bars) and then just refill a minimum amount to not have the fuel light on (about 4-5L or 1-1.25 gal)
No need to run it until it quits. Not likely to harm anything, but why even go there and risk it?
 

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To get way down into the weeds for those thinking running out of gas will push the next FMM off for 12 months if you only add the minimum amount of fresh...

I’ve run out of gas twice during an FMM. When you do that, there’s still a very small amount of gas in the lines. Theoretically when you now add gas, it’s all fresh gas, and you should have 12 months until your next FMM. In practice, I fill my gas tank after an FMM, because I usually take a long vacation drive once a year that requires a fill up or two, so I don’t mind driving around with gas in the tank (sometimes it’s 12+ months between trips, hence the FMM). I’ve discovered my next FMM after running out of gas and then filling the tank occurs 363 days later, or 2 days before the 12 months is up. Our forum member Ari_C also performs an annual FMM by running out of gas (he might have found an alternative method in recent times). He then adds the bare minimum, ~1.5 gallons. His next FMM occurs ~318 days later. IOW, the small amount of "old" gas remaining in the fuel lines after you run out of gas, when combined with a tank full of new gas, has only a 2-day-earlier impact on my next FMM. The same amount of "old" gas, when combined with only the minimum ~1.5 gallons of new gas, has a slightly stronger impact on the "average age," and the next FMM comes several weeks sooner.
 

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Our forum member Ari_C also performs an annual FMM by running out of gas (he might have found an alternative method in recent times).
I believe his alternate method is a new BEV.
Haven't seen Ari post in a long while.
 
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