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Should I use premium gas? Explained like you're 5.

Discussion in 'Prius c Fuel Economy' started by Alexinnitro, Oct 14, 2014.

  1. Alexinnitro

    Alexinnitro New Member

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    The different numbers you see at the gas tanks is called the "Octane Rating". It represent different amounts of Octane in the gasoline.

    Octane is a part of Gasoline that is harder to ignite and detonate than other ingredients of Gasoline. This means that the more Octane a fuel has, the more stable it is.

    When an engine is run under high stress, such a high revs or heavy towing-loads, it might start to do whats called "Knocking". Engine Knocking is when the fuel in an engine's pistons ignites and fires prematurely.

    If this happens early enough in the engine's cycle, this can severely damage the engine.
    Octane, being more stable than the rest of gasoline, offsets this risk of Engine Knocks.

    So a high performance car, like a Ferrari or a Lamborghini will require a higher Octane-Rated fuel in order to prevent itself from destroying its own engine.

    A lesser performance car, like a Honda Civic, won't require as high an Octane-Rating because it doesn't put its own engine under the same amounts of stress.

    One last thing about Octane: Always use the lowest grade of fuel that your car will take. Not only is it cheaper, but because it takes less energy to detonate, you car will get better fuel milage. The lower the Octane, the easier the energy in the fuel is released. Putting high Octane fuel in your car will only make you car less fuel-efficent and less powerful.

    The Wikipedia article, in case you want to read more. Octane rating - Wikipedia, the free encyclopedia

    DISCLAIMER

    This is from an ELI5 post on reddit.
     
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  2. bisco

    bisco cookie crumbler

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    and thank you.
     
  3. Easy Rider 2

    Easy Rider 2 Senior Member

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    You were doing pretty good up to here.
    You should have quit while you were ahead. :)

    This part is just meaningless rambling.
     
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  4. ztanos

    ztanos All-around Geek!

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    Then perhaps you can explain this phenomenon?

     
  5. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    There are always going to be people that buy the $3 bottle of "Nursery Water" to give their crumb-snatchers as a sincerely-felt belief that it has to be better than regular "bottled water"...because....well....it just HAAS to be better because it costs more.

    More expensive is more expensive.
    The reason that there are 1,243 threads on this forum about Premium gas is that this is a forum for people who dig Priuses.
    They want the VERY best for their 'baby'.

    Oil companies know this.
    That's why gas that is a little harder to detonate than other gas is called "premium" and people often confuse a higher octane rating with more energy content.
    Oil companies know this too.

    Me?
    I like things simple.
    Since there's no measurable difference in my car, I'm not to fork over money for no good reason.
    If I squint my eyes and hold my head at a certain angle, I can almost see a difference between E0 and E10, but I'm not going to spend my life searching out gas stations that (claim to) sell E0 so that I can spend more money at a grungier Mom and Pop station.
     
  6. ztanos

    ztanos All-around Geek!

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    I agree with it not being worth the effort.... but, I noticed more than an almost difference between E0 and E10. I'd say more than a 5% difference. But to me that's not worth the hunt and it was on my Saturn not the PC, so there could be differences there as well.
     
  7. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Ethanol content is drifting off-topic. Maybe that's a good thing?
     
  8. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    At least in some parts of the US, 87 octane is E10 and 91 Octane is E0, so the two do get confused.
    Gen 2, Gen 3, and v show no improvement with higher Octane but Ethanol does effect them.
    I do not own a c, but some owners claim Octane alone does affect them, and I can't prove them wrong.
    as always, my advice is to ignore MPG and follow the money. If E0 improves MPG by 5%, it better cost less than 5% more. If higher Octane improves MPG by 5%, it better cost less than 5% more.

    Driving out of your way to get gas almost never makes financial sense, even if it improves your MPG, as you waste gas getting to the station.
    (I can get E85 'only' 35 miles away. The Prius is not supposed to use E85, MPG is about 30% less, it costs more than regular, and it is 70 extra miles on a tank for no real purpose)
     
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  9. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    It's like switching the topic from UFO sightings to 'Elvis isn't dead' theories.
    It's worth grinding through those discussions only because there are folks out there who are going to go out their way and/or out of their pockets to put "the good stuff" in their tanks.
    The good news is that it's not going to hurt the car.....unlike some of the weightier topics like oil change intervals and viscosity debates, which in all honesty probably still won't hurt the car.

    SSDD. ;)
     
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  10. bisco

    bisco cookie crumbler

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    i saw elvis on a plane the other day.:cool:
     
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  11. GrumpyCabbie

    GrumpyCabbie Senior Member

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    Do you think this thread is one of those we discussed?
     
  12. wjtracy

    wjtracy Senior Member

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    I would say the Reddit post is factually incorrect. Bad science written by someone who wants to send a message that Premium is not needed. The message is OK for most US motorists but the theory is wrong.
     
  13. bisco

    bisco cookie crumbler

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    indubitably.
     
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  14. wjtracy

    wjtracy Senior Member

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    ...the topic is going to keep coming up, because when folks own a Prii @ 50MPG you can start to measure some fuel differences. Further there is an unexplainable urge to max out MPG. When you see 17.0 MPG on your minivan and it could be 17.2 MPG, who cares? But when you see 49 MPG on a Prius, and it could be 50 MPG, well 49's just not going to cut it.
     
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  15. Farfle

    Farfle Member

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    I think I enjoyed driving more before I got my Aqua. Life was so much simpler and less stressful then....​
     
  16. GregP507

    GregP507 Senior Member

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    I posted a video link a while back which thoroughly debunked the Premium fuel myth. To sum it up in one sentence: Unless your engine is designed for Premium, you will be paying more for something that gives you no tangible benefits whatsoever.
     
  17. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    The gas stations with their array of pumps are NO help. And it's a slam dunk that this is intentional. I can just picture the cartoon for a sensible gas station:

    Nothing but regular pumps, and off in the corner of the lot, next to air and water* hoses, a solitary high octane pump, kinda grubby and neglected.

    * Any point to that water hose either, well except as a simple water source? I mean: I always picture a model T rolling up, steam pouring from under the hood, Ma and Pa kettle in the cab.
     
    #17 Mendel Leisk, Oct 28, 2014
    Last edited: Oct 28, 2014
  18. ztanos

    ztanos All-around Geek!

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    So that's a hard rule then?
     
  19. wjtracy

    wjtracy Senior Member

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    I feel Greg is talking about the situation in Canada which is a little different than USA. Canada the gaso companies still apparently hype up Premium as better.

    In the USA, the EPA regs largely take away the gaso company freedom to formulate gaso and so nobody here hypes up premium anymore. The rule is to use Regular for most cars.

    Some USA motorists still incorrectly infer Premium is better and still use Premium, so some here feel the need to advise them that they are wasting money, which could be true.

    Others here may be using Premium because there IS a chance they could see better MPG. That's because energy content of gasoline is not a hard spec (OCTANE rating is the key spec) so MPG can vary a little bit (eg; during winter fuel blend, or ethanol etc). Probably does not pay off but some like to see if they can measure better MPG or cruising range.
     
  20. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Which will save them money.