1. Offline

    k.s.c Junior Member

    Member Since:
    Mar 18, 2012
    Posts:
    75
    Likes Received:
    6
    Location:
    SW Florida
    Your Vehicle Year:
    2012 Prius
    Model:
    Five
    My wife never forgets anything (especially when I screw up) and when we went to get some gas today I naturally went for premium since that was what I was used to in my previous car (this was the first time at the pump with the prius). My wife quickly yelled at me and informed me that during the orientation that I got when I bought the prius, I was informed not to put in premium and only use regular. I honestly don't remember hearing that but then again I was also too excited about the new car that a lot of what was being said went through one ear and out the other. I believe that they said I had to use gas with no more than 10% ethanol but I never heard premium being bad.

    Can anyone shed some light on this. We ended up leaving the gas station without filling up due to the fact we couldn't agree on things. Who is right here? Can I use premium or does it have to be regular?
  2. Offline

    paycee Junior Member

    Member Since:
    Sep 26, 2008
    Posts:
    48
    Likes Received:
    3
    Location:
    USA
    Your Vehicle Year:
    Other Hybrid
    Model:
    N/A
    You can search from previous posts as this has been covered more than once but personally for me I'd go for a regular gas since its cheaper and prius engine is made to perform with a regular gas... but then again I have a gen II..
  3. Offline

    Mocmylov Junior Member

    Member Since:
    Mar 15, 2012
    Posts:
    18
    Likes Received:
    5
    Location:
    Escondido
    Your Vehicle Year:
    2012 Prius
    Model:
    Two
    Premium should be fine. The computer will adjust to the difference in octane. Just don't expect any better performance out of it or anything ;)
  4. Offline

    k.s.c Junior Member

    Member Since:
    Mar 18, 2012
    Posts:
    75
    Likes Received:
    6
    Location:
    SW Florida
    Your Vehicle Year:
    2012 Prius
    Model:
    Five
    so basically the car CAN use premium but in the sense of performance or longevity of the car, using premium does not "help" the car in any way and is basically paying a few dollars more and not getting anything more in return.

    So technically I was correct yet she was saving us money.
  5. Offline

    krazypriuslady New Member

    Member Since:
    Mar 17, 2012
    Posts:
    228
    Likes Received:
    10
    Location:
    metro Wash DC
    Your Vehicle Year:
    2011 Prius
    Model:
    Three
    my dealer told me regular gas only.
  6. Offline

    Michgal007 Senior Member

    Member Since:
    Aug 24, 2006
    Posts:
    1,319
    Likes Received:
    89
    Location:
    Macon, GA
    Your Vehicle Year:
    2006 Prius
    Model:
    N/A
    Use regular. Premium is a waste of money and some owners say it lowers the mpg.
  7. Offline

    MJFrog PHEV Disabled - cold weather

    Member Since:
    Jul 21, 2009
    Posts:
    762
    Likes Received:
    241
    Location:
    SE Michigan
    Your Vehicle Year:
    2004 Prius
    Model:
    N/A
    Yes, you were correct...it shouldn't hurt. Yes, she was correct...dealer recommendation and saves $$$$.

    Apologize immediately!
  8. Offline

    The Electric Me Go Speed Go!

    Member Since:
    May 22, 2009
    Posts:
    4,608
    Likes Received:
    1,492
    Location:
    Undisclosed Location
    Your Vehicle Year:
    2013 Prius
    Model:
    Two
    I wouldn't sweat it.

    I remember Pre-Generation 3 release, it actually took a long time for Toyota to confirm what grade of gasoline the Gen 3 Prius did take.

    Regular is recommended and cheaper, so that is what I would use. But if you accidently put a tank of higher octane in? It wouldn't be the end of the world.

    Infact, just a ritual I have gone through for decades with my vehicle, whatever it might be, is every Oil Change, I run a tank of premium with a treatment of Techron included. Usually take a highway drive. I don't know if it really helps but my logic is it keep the fuel injection system cleaner.

    Usually these vehicles are designed with a minimum required octane, but if you exceed it, by accidently or conciously choosing premium it won't do any damage. You'll just be paying more for the tank.

    If you think about it, if running a tank of premium through a vehicle that's requirement is regular could do any damage? The amount of times this would happen would create a total mess for everyone.

    I live in Oregon which is a State that doesn't allow self serve. It's attendant based. And usually at least once a year the attendant will grab the wrong nozzle and fill with premium even though I requested regular.

    Except for the extra $3.00? It's a no harm, no foul situation.

    So in short, Your Wife was right...use regular. If you accidently fill with a tank of Premium? Uh...don't tell your wife, and you'll be okay.
  9. Offline

    Mike500 Interessen-Gemeinschaft Prius

    Member Since:
    Mar 1, 2012
    Posts:
    1,851
    Likes Received:
    463
    Location:
    Upstate, SC
    Your Vehicle Year:
    2012 Prius v wagon
    Model:
    Two
    The myth about premum is that, because it costs more, it is better.

    Unless you need the "octane" rating for the particular vehicle to prevent "pinging," it is NOT better.

    Gasoline is composed of hydrocarbon chains of 6, 7, or 8 carbions linked together. Octane means the mix ratio contains more 8 chain carbion molicules. Higher octain means that it will not "pre-detonate" under higher pressures under higher compression ratios.

    It does nothing for lower compression engines.

    Under usual conditions, I do not purchase premium because;

    It is a lower seller, which means that it is less "fresh" than regular and has been in the underground tank longer to collect more water through condensation.

    To achieve higher octane, premium has a larger percentage of ethanol. If you look on the pump at the gas station, there is a sticker saying that it can contain up to 10% ethanol. Ethanol provides less mileage and collects condensation water more than gas without or with a lower precentage of ethanol in the mix.

    Ethanol must be used, since MTBE as an octane booster (methylbutyltertiaryether) was banned in 2005 in many states.

    So, regular is better functionally and financially in any model Prius.
  10. Online

    JimboPalmer Tsar of all the Rushers

    Member Since:
    Apr 14, 2009
    Posts:
    7,245
    Likes Received:
    2,146
    Location:
    Greenwood MS USA
    Your Vehicle Year:
    2012 Prius v wagon
    Model:
    Three
    Bob Wilson (we all miss Bob Wilson) did a great deal of actual testing and graphing of ideas and not just accepting conventional wisdom. He found no MPG difference between octane grades but did find that full throttle acceleration up extended hills showed more power. Should you plan to cross the Rockies, that might be the time to buy Premium. But you won't see better mileage anytime.
    DaveC2007 likes this.
  11. Offline

    Brett. Junior Member

    Member Since:
    Mar 15, 2012
    Posts:
    137
    Likes Received:
    22
    Location:
    NJ
    Your Vehicle Year:
    2011 Prius
    Model:
    Two
    Thee Prius engine is 13.0:1 that's hot roddin for a little 4 banger, haha.

    Doesn't need premium though, the engine hardly sees high enough RPM's to stay running let alone increased cylinder pressures. Detonation is virtually non-existent on vehicles without forced induction these days with modern fuel injection and cooling systems. Unless someone has been using crappy gas for 200K and the pistons are domed with carbon build up.

    Most vehicles these days are tuned for 87 octane fuel or thereabout and adding higher octane can lower gas mileage because of the 90+ octane fuels resistance to ignite. (As explained above me)
  12. Offline

    dustoff003 Blizzard Brigade #003

    Member Since:
    Dec 27, 2010
    Posts:
    1,328
    Likes Received:
    319
    Location:
    Waianae, HI (Oahu)
    Your Vehicle Year:
    2011 Prius
    Model:
    Five
    What does your owners manual say?


    Posted from my iPhone via the Tapatalk app.
  13. Offline

    kevinwhite Member

    Member Since:
    Jun 10, 2006
    Posts:
    139
    Likes Received:
    11
    Your Vehicle Year:
    2006 Prius
    Because of the Atkinson cycle the Prius uses, the effective compression is about 9.0:1 (about 1/3 of the mixture is blown out of the cylinder during the first part of the compression stroke.

    kevin
  14. Online

    JimboPalmer Tsar of all the Rushers

    Member Since:
    Apr 14, 2009
    Posts:
    7,245
    Likes Received:
    2,146
    Location:
    Greenwood MS USA
    Your Vehicle Year:
    2012 Prius v wagon
    Model:
    Three
    The Prius has an Atkinson Cycle engine, the expansion ratio is 13 to 1, but the compression ratio is about 30% lower as the intake valves do not close until the piston is about 30% up the cylinder.

    Measuring from Bottom Dead Center to Top Dead Center does not yield accurate compression info in a Atkinson Cycle engine.
  15. Offline

    kenoarto Member

    Member Since:
    Feb 7, 2006
    Posts:
    444
    Likes Received:
    62
    Location:
    Chicago, IL
    Using incorrect octane can do permanent and catastrophic damage to many cars. The owners' manual says to use regular gas. Consumer Reports has done a very good study on this. Why would you choose to take such a risk?
  16. Offline

    Mike500 Interessen-Gemeinschaft Prius

    Member Since:
    Mar 1, 2012
    Posts:
    1,851
    Likes Received:
    463
    Location:
    Upstate, SC
    Your Vehicle Year:
    2012 Prius v wagon
    Model:
    Two

    Using higher octane gas does no damage to an engine requiring lower octane gas. Since highe roctane gas cost more, the only dmage that you're doing is to your wallet.
  17. Offline

    V8Cobrakid Green Handyman

    Member Since:
    Jun 6, 2004
    Posts:
    3,778
    Likes Received:
    136
    Location:
    Park View, Los Angeles, CA. U.S.A
    Your Vehicle Year:
    2004 Prius
    Model:
    N/A
    running higher gas can harm the vehicle.. it's not the engine.. it's the catalytic converters. now... those cost a pretty penny and i wouldn't want to be gumming one up with unburnt fuel just because i tossed in premium that the car simply spit out as unburnt exhaust. (of course this would take a lot.. and i mean a lot of premium fill ups to do)

    point being.. anything outside of what they ask, and you can technically cause more harm than you need to (i say More harm because running it technically wears it too)


    running anything over 10% ethanol can harm the vehicle (rubber gas lines and such)... if someone is running a generation II, it can melt the gas bladder.. which can spit up pieces and destroy the rest of the engine.
  18. Offline

    Brett. Junior Member

    Member Since:
    Mar 15, 2012
    Posts:
    137
    Likes Received:
    22
    Location:
    NJ
    Your Vehicle Year:
    2011 Prius
    Model:
    Two
    Thank you for the engine info guys i gotta do some more research now, gives me something to do after work.
  19. Offline

    Mike500 Interessen-Gemeinschaft Prius

    Member Since:
    Mar 1, 2012
    Posts:
    1,851
    Likes Received:
    463
    Location:
    Upstate, SC
    Your Vehicle Year:
    2012 Prius v wagon
    Model:
    Two
    What premium gas has over 10% ethanol?


    E85 should be run only in cars designed for E85.
  20. Offline

    tach18k Member

    Member Since:
    Feb 21, 2012
    Posts:
    394
    Likes Received:
    35
    Location:
    SoCal Beach Area
    Your Vehicle Year:
    Other Hybrid
    On my 2012 II, I used regular 87 oct gas, got great milage, 47.5. I switched to mid grade 89 oct, my milage dropped to 44.2. I went back to 87 and i'm back at 47.5. go figure.....These figures are based on fillups and not Comps, also I saw my Comps drop too, about the same as I saw in milage.

Share This Page