different gas, different gas mileage

Discussion in 'General Motoring' started by Ashton Crusher, Mar 3, 2010.

  1. I've always liked chevron gas because it has techroline, which is one
    of the best fuel detergents. But I've noticed lately that when I buy
    Chevron my 2009 PT seems to get about 2 - 3 mpg worse gas mileage. My
    other typical fill up is some "FastGas" type place. This change has
    happened often enough that I'm pretty sure it's not completely my
    imagination. Anyone else noticed such a change from one brand to
    another? On the FastGas I usually get 24.5 on my typical driving
    cycle, 70% commute, on the Chevron it drops down to about 22.
     
    Ashton Crusher, Mar 3, 2010
    #1
  2. Ashton Crusher

    AZ Nomad Guest

    Brands have different additives, but nothing that should affect
    gas mileage given equal octane. Most likely it's just plecebo effect.
     
    AZ Nomad, Mar 3, 2010
    #2
  3. Ashton Crusher

    Bill Putney Guest

    Amount of alcohol added, seasonal blend formulations and accuracy of the
    blend, quality of gas as far as moisture/water due to condensation that
    collects in the tanks, particularly during th winter can be a factor.
     
    Bill Putney, Mar 3, 2010
    #3
  4. Ashton Crusher

    Rob Guest

    10% ethanol out here and that's not a seasonal thing.

    local techs recommend a small amount of amsoil 2 stroke in your gas tank but
    a very small amount, about 1 ounce per 10 gallons i think but i am checking
    on that now.
     
    Rob, Mar 3, 2010
    #4
  5. Ashton Crusher

    Scott Dorsey Guest

    Are these by any chance techs who make a large profit on replacing
    catalytic converters?
    --scott
     
    Scott Dorsey, Mar 3, 2010
    #5
  6. Ashton Crusher

    News Guest



    "Ah, you used a bit too much..."
     
    News, Mar 3, 2010
    #6
  7. Ashton Crusher

    m6onz5a Guest

    lol really


    Well.... maybe it's no different than putting Marvels Mystery Oil in
    the fuel???
     
    m6onz5a, Mar 3, 2010
    #7
  8. Ashton Crusher

    Vic Smith Guest

    Hard to get accurate mpg without controlled highway driving.
    Catching more red lights, more idling, and a few pedals to the metal
    could account for that difference.
    You need multiple tanks of the same stuff, then multiple tanks of the
    other, and careful attention to driving style.
    If there's a cold snap during one brand test but not the other, toss
    everything out, and start again.
    You might find a difference.
    But do you really want to do that?

    --Vic
     
    Vic Smith, Mar 3, 2010
    #8
  9. Ashton Crusher

    Don Stauffer Guest

    While I agree that different brands likely will have SOME difference in
    energy content and milage, that seems like a lot.

    You need to do a good milage test and compile statistics.

    You need to do about ten samples to get a real valid test, so this is
    ten tankfuls each. Then figure the milage individually for each of the
    ten tankfuls and use one of those "statistics" calculators. You need to
    determine the Probable Error of each set of tests.

    A number of years ago I bought a Dodge Neon that would run on either
    regular or premium but they recommended premium and said I would get
    better milage on premium.

    I ran ten tankfuls of each. The tests said I got about 0.3 mpg better
    on regular. But... the probable error on the testing calc'd out at 0.5
    mpg. It is very hard to measure mpg differences of about one mpg.

    But, two to three ought to show up well.
     
    Don Stauffer, Mar 3, 2010
    #9
  10. As I've posted before, my 2001 PT gets terrible milage.
    Here in Western PA and Eastern Ohio there's a huge supermarket chain,
    Giant Eagle.
    They have GetGo gas stations. For every $50 you spend at the market,
    you get 10¢
    off a gallon of gas. The only time I use GetGo gas is when I have a
    free tank coming.
    My cruiser on BB, Sunoco or Shell averages 16-17 mpg. My trips never
    change. I'm
    usually going to the same places the same number of times between fill
    ups.
    On the GetGo gas, I'm lucky if I come close to 13-14 mpg.
     
    Pete E. Kruzer, Mar 3, 2010
    #10
  11. Ashton Crusher

    Scott Dorsey Guest

    What have you done about it? Any codes in the ECM? Checked for vacuum
    leaks? Changed plugs, cap and rotor? Checked fuel pressure? Or just
    ignored it?
    --scott
     
    Scott Dorsey, Mar 3, 2010
    #11
  12. Ashton Crusher

    sctvguy1 Guest

    I get better than that with my 41 Windsor! 245.5 flathead 6.
    I had two PTs: a sedan and a convertible. Both got terrible mileage, the
    convertible with the 180hp turbo, got around 17-22 max. The sedan, with the
    base engine would get around 19-26. This is Florida with flat roads
    everywhere.
     
    sctvguy1, Mar 3, 2010
    #12
  13. Ashton Crusher

    Steve Guest


    The best I've ever done on my wife's 2005 PT (automatic) was 27.5 on the
    highway. More typical is 24-25, and around town is 20 to 21. I don't
    consider that particularly good since her 3.5L Vision TSi that
    out-weighed the PT by a few hundred pounds and out-powered it by almost
    100 horsepower got even better mileage (30 highway when it was in its
    prime). But what I really can't understand why your 2001 does so badly.
    I know other owners of early PTs which were similar to yours, though.
     
    Steve, Mar 3, 2010
    #13
  14. Ashton Crusher

    Bill Putney Guest

    Maybe it's different where you are, but here in VA, the decals on the
    pumps say something to the effect "May [ < key word] contain up to [ <
    more key words] 10% ethanol", so to me it is a real unknown, and who
    knows *what* determines from one batch to the next what the exact
    content is?

    --
    Bill Putney
    (To reply by e-mail, replace the last letter of the alphabet in my
    address with the letter 'x')
     
    Bill Putney, Mar 3, 2010
    #14
  15. Ashton Crusher

    Tegger Guest

    (Scott Dorsey) wrote in



    Notice "Rob" hasn't got back to us about the results of his "checking"?
     
    Tegger, Mar 3, 2010
    #15
  16. Ashton Crusher

    Tegger Guest



    I always record each and every fillup, writing down the odometer reading,
    how much went into the tank, and even the date and price.

    Over 19 years, with an average of almost 18,000 miles per year, I have yet
    to notice /any/ discernible difference in mileage from one brand to
    another.

    Because accurate results require very long-term measuring over many
    fillups, I run into seasonal temperature variation, which is a confounding
    factor.

    However, there /is/ considerable difference in mileage from summer to
    winter and back again. This difference appears to be unrelated to gasoline
    brand.

    There is also considerable difference in mileage when taking a single
    fillup against the others. I've seen as much as 15% variance in mileage
    between individual fillups. The variance is erased when many fillups are
    included in the calculation. This is true even when batches of fillups
    overlap.

    I used to think I had seen an approximately 2% drop in mileage between 87-
    octane and 91-octane, but now I'm not so sure. My test periods extend over
    two or more seasons, so that 2% could easily be explained by temperature
    variation.

    These are just my very careful observations. Take them as you will.
     
    Tegger, Mar 4, 2010
    #16
  17. Ashton Crusher

    Tegger Guest


    Clarification: the word "however" should not be in this paragraph. I
    ngelected to excise it while rearranging my previous post.
     
    Tegger, Mar 4, 2010
    #17
  18. Ashton Crusher

    Rob Guest

    that's because some of us have a job.......i cant sit on the web and surf
    all day
     
    Rob, Mar 4, 2010
    #18
  19. Ashton Crusher

    Rob Guest

    yeah same thing down here.......up to 10%.


     
    Rob, Mar 4, 2010
    #19
  20. Ashton Crusher

    Tegger Guest



    But you said you were "checking on that now". So you're admitting you were
    fibbing?
     
    Tegger, Mar 4, 2010
    #20
Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.