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Seller told me his Prius takes 95 Octane. Can I switch to 87?

Discussion in 'Newbie Forum' started by 7Lowe, Sep 6, 2013.

  1. 7Lowe

    7Lowe Junior Member

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    I just bought a used Prius and the seller said (after the deal) that "it takes 95 octane." Now it never came up before because I had read up fairly extensively online and the manual I saw online said 87.

    Is it ok to drop back to 87? I ask because I used to work at a gas station and the owners would put the premium grades on sale for a weekend at the same price as the regular. They said that the cars "got used" to the higher grades and then wouldn't run as well if you went back down. So, it was worth the very slight loss during the sale since it would get more Premium buyers in the long run (which was much more profitable.)

    Is there any truth to that or am I ok to switch to 87?
     
    #1 7Lowe, Sep 6, 2013
  2. bisco

    bisco cookie crumbler

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    never heard of such a thing, but what do i know?:confused: i think your fine on 87 like the rest of us.
     
    #2 bisco, Sep 6, 2013
  3. SteveLee

    SteveLee Active Member

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    87 makes my trusty steed happy happy happy, and me too.
     
    #3 SteveLee, Sep 6, 2013
  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Are you still in Portugal? Does you county measure Octane via RON? If so, 91 RON Octane is what you want.

    If you have moved to the US, then Octane is measured via AKI and 87 AKI Octane is what you want.

    Octane rating - Wikipedia, the free encyclopedia
     
    #4 JimboPalmer, Sep 6, 2013
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  5. 7Lowe

    7Lowe Junior Member

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    I am still in Portugal. Thanks a lot for the info!

    I had no idea there were different octane measurements.
     
    #5 7Lowe, Sep 6, 2013
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  6. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Total nonsense. There's actually VERY few cars that need higher octane, it's purely due to high compression ratio of the engine, and it would be specified in the owners manual.

    The oil companies don't mind though, they've got to sell the higher octane gas to someone...
     
    #6 Mendel Leisk, Sep 6, 2013
  7. 7Lowe

    7Lowe Junior Member

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    Just got back from the gas station. 95 was the lowest that they had, so that's what I got. Looking at the wikipedia article above I think that may be the lowest sold here.

    Tank was pretty low (1 pip on display) when I filled up. I think I got about 40L @ 1.64EUR/L for a total of 65.6EUR. Or, in US terms, 10.6Gal @ $8.17/Gal for a total of about $86.60!
     
    #7 7Lowe, Sep 6, 2013
  8. Faine

    Faine New Member

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    I've always been curious as to if the octane rating in the owners manual was the actual required octane rating for optimal running or the rating on the pump that should be used. I have a friend who is a regional manager for a gas station in the area I live in and he says to take the middle grade in a car that wants 87 octane because the octane rating is what it was measured at when the fuel left the distribution facility and that the fuel you get from the pump is generally 3 to 7 octane lower (depending on how old the fuel is) than the number on the pump. Of course I've never researched that myself, I always thought he knew what he was talking about.
     
    #8 Faine, Sep 6, 2013
  9. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    All higher octane gas gives you is greater resistance to pre-ignition. It's harder to ignite.

    With an engine in the regular compression range, with no pre-ignition problems, buying the higher octanes is pointless.

    That said, with computerized ignition systems, the car might be detecting pre-ignition and retarding timing to avoid it. But I think that's a long shot.

    Also, if the manufacturers say regular octane is ok, I can't see them saying "well, that's if you get it fresh from the factory".
     
    #9 Mendel Leisk, Sep 6, 2013
  10. bisco

    bisco cookie crumbler

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    i don't know anything about octane, but my 3 pri have all run fine on 87. knocking was the only thing i ever heard about growing up.
     
    #10 bisco, Sep 6, 2013
  11. wjtracy

    wjtracy Senior Member

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    OK I was going to say 10.6 gal sounds high for USA 2005 but we have flexible fuel tank, I think you probably have a fixed volume gasoline tank which is nice you can get a little more in there than we can re: cruising range.
     
    #11 wjtracy, Sep 7, 2013
  12. 7Lowe

    7Lowe Junior Member

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    All those numbers are estimates from memory. I know my friend looked at the receipt and said 40 something liters, so I just went with 40. I remember the price on the pump was 1.6x, and he thought it was 1.64. Half the receipt tore off in the machine so we didn't see any price there. At any rate it's fairly accurate.

    Also, you are right that tank is fixed volume.
     
    #12 7Lowe, Sep 7, 2013
  13. cary1952

    cary1952 Member

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    I live at 4000 elevation and 85 octane is just fine at this level. 87 octane should be fine.
     
    #13 cary1952, Sep 8, 2013
  14. Jeffrey Jessup

    Jeffrey Jessup Member

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    Sure makes our $3.70/gal. sound like a bargain!
     
    #14 Jeffrey Jessup, Sep 10, 2013
  15. telmo744

    telmo744 HSD fanatic

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    Welcome to Priuschat.
    There are some european chatters here.
    Portuguese mode selected:
    Eu sou um deles. Chateio muitas vezes
    :p
    Bem vindo!
     
    #15 telmo744, Sep 10, 2013
  16. 7Lowe

    7Lowe Junior Member

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    Obrigado (that's most of the Portuguese I've learned so far), I'm glad to be here on the forum and especially glad to be here in your country. So far I've found it to be incredibly beautiful and am somewhat in awe of the age and history of the place.
     
    #16 7Lowe, Sep 10, 2013
  17. telmo744

    telmo744 HSD fanatic

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    #17 telmo744, Sep 11, 2013
  18. massparanoia

    massparanoia Active Member

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    US AKI is RON*0.95. So 95 RON would be 90.25 AKI. So with 91 US octane you're all set.
     
    #18 massparanoia, Sep 11, 2013
  19. ToyotaPrius2005

    ToyotaPrius2005 Junior Member

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    I have been using 87 octane for the last 189,000 miles and have seen no problems

    would be interesting to see if there is any gas mileage difference when using the different octane
     
    #19 ToyotaPrius2005, Oct 9, 2013
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