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Can my gasoline get old and cause problems?

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by Krypto, Jul 18, 2020.

  1. Krypto

    Krypto Junior Member

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    I rarely drive my Prius Prime more than 25 miles since this pandemic really kicked in. I haven't put gas in my tank since early February because I'm able to get around on just electric. So, I'm wondering if my gasoline will get old and start to cause problems. Should I run out the gas that's in my tank, or is it ok to ride around for the next month or so with what will be about 6 month old gasoline? Come September my commute will be about 50 miles so I'll be using up the gasoline (hopefully!).
     
  2. bisco

    bisco cookie crumbler

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    i think the o/m has the answer. i forget exactly, but using it up once a year is sufficient.
     
  3. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    eh, it's not the best but 6 month old gas is not terrible either. Try not to ever get caught in a pandemic shutdown again, okay?

    I understand that the car designers thought of it, and when left to automatically manage its own drive modes it will try to use the engine more when it thinks the gas is getting old. The car has no direct way of measuring the quality of the fuel- it's just going from a timestamp on the last time the level went up.
     
  4. Rob43

    Rob43 Senior Member

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    Consider switching over to E0 gasoline, it might be worth the extra drive to buy it and extra cost...

    You'll also get better MPG's when using E0 gasoline.



    Rob43
     
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  5. sam spade 2

    sam spade 2 Senior Member

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    Consult your owner's manual.
    How old was the gas in the tank when you stopped adding regularly ?
    I think the general consensus is not to worry until you pass the one year mark.
    But it would make me nervous......and taking a ride (on gas) might be a nice diversion.
     
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Well Toyota says to add at least a total of 20L (5.28 US gal) every 12 months. (so it doesn't have to be 20L all at once but as long as 20L or more has been added within a 12 month period).

    Half of my tank is from last Nov and the other half from Mar so I think I should be good through the fall at least.

    If you're going to start burning fuel in Sept, 7 months should be ok. And at least you're burning it to commute, rather than "for the heck of it".

    If you want peace of mind, you could always add fuel stabiliser but the Prime's fuel tank is pressurised so it should be good. I mean, Toyota wouldn't want to recall the Primes due to clogged fuel injectors so I would think they've taken low fuel usage into account.
     
  7. sam spade 2

    sam spade 2 Senior Member

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    No. They want to sell you "fuel injector service"......which really amounts to pouring a ~$7 can of Techron into the tank and charging you $70. :eek:
    :mad:
     
  8. fuzzy1

    fuzzy1 Senior Member

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    Those are a different "they". The independently owned stealerships selling trumped-up "fuel injector service" and other unneeded profit adders are not the same corporate entity that has to pay for recalls.
     
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  9. Krypto

    Krypto Junior Member

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    Thanks everyone for your quick answers!
     
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  10. fuzzy1

    fuzzy1 Senior Member

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    Re: what the Owner's Manual says:

    [​IMG]
     
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  11. Mambo Dave

    Mambo Dave Active Member

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    I imagine this could change based on where you live - humidity levels in the regular air are much higher here than in other states, so the fuel is in regular contact with more water vapor.

    Alcohol in common USA gasolines is hydrophilic, so it's a detriment to vehicle owners that the US lawmakers allowed the corn industry to sell them on. It makes an utter (en expensive) mess of boat fuel systems that are stored for any length of time.

    There is a general theory that the fuller one keeps their fuel tank, the less that fuel will be exposed to the humidity in the air. With already old gasoline, you may be creating more fuel degradation by not having a full tank on your short commutes - fuel sloshes around inside the tank, and the alcohol will bind to whatever water it finds in the air inside the tank. The more air you have, the more water you have in that air to bind to the corn-fuel.

    If you can find a pump with non-ethanol fuel (for boats, equipment, etc.) that is still being used regularly (fresh gas in the station's tanks), if I were you I'd fuel up there to mix really good gasoline with what was marginal gasoline when it was new. You may get a gas station attendant yelling at you for putting it into your car, but write them off. Non-ethanol gasoline lasts, and stays fresher, far longer.

    I'm going through a tank a week right now, so it's not a concern to me. I'm surprised so many here are still holed up at home.
     
  12. john1701a

    john1701a Prius Guru

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    That's too general. There is no humidity exposure. Our system is sealed to prevent exactly that.
     
  13. Mambo Dave

    Mambo Dave Active Member

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    So you're stating that - as the gasoline in our tanks gets lower, the entire system operates in a sealed vacuum state? Ever try to pump a fluid from a sealed container under vacuum?

    If you already have a pressurized tank of zero-water-vapor stable gas, like CO2 or Nitrogen, stored on your Prius to equalize the pressure differential in the fuel tank as the gas gets lower, then you got a better optioned car than I did!
     
  14. john1701a

    john1701a Prius Guru

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    Yes. I have be doing it for over a decade. Prius switched from bladder to pressure-seal back with generation 3.
     
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  15. Mambo Dave

    Mambo Dave Active Member

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    Pressure from ... what? I must be missing something.
     
  16. john1701a

    john1701a Prius Guru

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    To achieve the PZEV emission rating, evaporative emissions must be prevented. Toyota's system ensures the gas tank doesn't let anything in or out until you unseal for refilling.
     
  17. sam spade 2

    sam spade 2 Senior Member

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    Use your head John.

    The gas goes OUT. Absent a flexible bladder, something must go IN to replace it.
    That would be AIR.

    The regulations do NOT prohibit air going IN; it prohibits gas fumes from going OUT.

    The fuel system is NOT totally sealed. It can't be.
     
  18. john1701a

    john1701a Prius Guru

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    The point is the exchange is prevented... no in /out repeatedly. Only a tiny bit of air is left in, a dramatic reduction compared to unsealed systems. And whatever water enters then is simply burned with combustion, not accumulated like concern raises.

    Think about how this has already been used in practice since 2012 without issue.
     
  19. sam spade 2

    sam spade 2 Senior Member

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    Those are ridiculous claims.
    When the fuel level gets low, the amount of air in the tank is directly proportional to the amount of volume left empty by ~ 10 gallons of fuel that has been used.
    And water that condenses inside the gas tank is NOT "burned with combustion". It collects in the low points or blends with the ethanol if that is present.
    AND.....when the fuel tank gets real HOT.....because the whole vehicle gets real HOT.....some vapors are purged to prevent and explosion or pressure damage to fittings. Those vapors go through a vapor recovery system that tries to remove the gas fumes......and it does a fair job most of the time.

    You are in WAY over your head here. You need to just STOP.
     
  20. john1701a

    john1701a Prius Guru

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    Why are you arguing a well proven system?

    This was addressed ages ago by several automakers. It's not an issue, the variety of plug-in hybrids have taken that into account. Heck, Toyota even loosened their disclaimer from E10 to E15.

    This has already been dealt with.
     
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