+ Reply to Thread
Results 1 to 12 of 12
  1. #1
    paolenz
    Guest
    Location
    , ,
    Member No: paolenz's Avatar


    Yes | No

    regular unleaded vs. premium gas ?

    I have seen conflicting issues about this from different manufacturers regarding premium vs. regular fuel. Honda says it is not a important but BMW says that all the cars they manufacture require premium gas.
    Is is possible to use regular unleaded gas on an engine that requires premium? What will happen, other than the on-board computer going bonkers? WIll it ruin the engine or run rough?


  2. #2
    Registered Member
    Location
    , ,
    Member No: 71563 kbud is on a distinguished road kbud's Avatar
    Join Date
    Apr 2003
    Posts
    20,679
    Rep Power
    34


    Yes | No

    not sure but if they advise it stick to the specs!

    wouldn\'t risk it in my opinion, if u can afford everything that comes with owning a BMW you can definetly afford the extra $.10 a gallon for gas each fill up whats that an extra $2-3.00 a fill up at maybe 52 fill ups a year thats an extra $150.00 a year premium costs. Just get the good stuff! thats my $.02



    K-Bud
    E39 - 1999 540iA Sp. Titanium Silver/Black
    BMWCCA Member #39061 est. 04/03
    Roadfly Member #1001 est. 06/03


    RevHigh CAI
    Breyton Fr. Lip Spoiler
    Clear Rear,Fr.,Sides
    19" RDSport S4's 19x9et18 fr. 19x10et20 bk.
    SO3's 245/35F 275/30R
    Rolled Fenders
    M5 Kidneys
    M5 Swaybar
    AC Schnitzer Alum. Pedals
    30% Tint
    Trunk Storage Bin
    Fr.& Bk. S/S BMW Logo Plates



  3. #3
    Registered Member
    Location
    Madisonville, LA, United States
    Member No: 10028 mdernst is an unknown quantity at this point mdernst's Avatar
    Join Date
    May 2001
    Posts
    2,032
    Rep Power
    0


    Yes | No

    Re: regular unleaded vs. premium gas ?

    I think most cars that recommend or require premium unleaded will run on regular unleaded without damaging the engine. However, I think the digital motor electronics will adjust the engine operating characteristics such that it will run with reduced power and probably worse fuel economy.

    Mike Ernst
    2003 M5 Jet Black


  4. #4
    Registered Member
    Location
    Harrison Township, MI, United States
    Member No: 32141 kowached is an unknown quantity at this point kowached's Avatar
    Join Date
    Apr 2002
    Posts
    11,713
    Rep Power
    0


    Yes | No

    Premium is required by High Compression engines.

    3 things can be traded off in the combustion process: Performance (Ignition timing) vs. Compression ratio (can't change) vs. Octane rating.

    Your BMW probably has a 10:1, or 10.2:1 compression ratio, set at the factory. Low is 8:1, some hot rods use 13.5:1 (require 110 octane fuel)

    Octane is a fuels resistance to combustion. Lower octane fuels will "knock" when run in high compression engines. Note: adding high ocane fuel to a low compression engine will NOT increase its performance, just as adding 110 octane fuel to your BMW will NOT increase its performance. People get confused because high octane fuels are required for powerful (high compression) engines to run properly, but its the compression that creates the power, the high octane fuel only allows it to happen.

    Octane Rating is the only decision that you can personally make. The car will dial back the Ignition Timing (performance) through the use of knock sensors when lower octane fuel is used, but this lowers performance, but does not damage the engine in any way. Its your decision, I also like the better additive package that most high octane fuels provide.



    Later,
    Dave

    For a great guide to E39 online resources, answers to many common questions, and help that will you get started out on the right foot here at Roadfly, check out the Unofficial Roadfly Welcome Package.

    E39 - 1998 540iA Sport (11/97 Production)
    E30 - 1989 M3 (44k miles)
    1979 Triumph TR7, still have my first car ;-)
    Past cars:
    E21 - 1980 320i (sold at 130k)
    E23 - 1986 735i
    Proud to be a Roadfly Inner Circle member (Member #32141).
    I am a BMW Car Club of America member (#111247), are you?



    Is it the new blues mobile or what? (original movie wav)

  5. #5
    User Level 8
    Location
    Everett, WA, United States
    Member No: 32419 gregory528iT is an unknown quantity at this point gregory528iT's Avatar
    Join Date
    Apr 2002
    Posts
    12,254
    Rep Power
    0


    Yes | No

    Definitions

    I agree with everything you said.. except on how the words might be interpreted. "Premium" = 91, 92 or 93 Octane gas (depending on your state) (WA = 92, CA = 91, IL =93) etc.
    10:1 or 10.5:1 compression engines are mid compression engines Generally speaking, "Premium would be required on "mid compression engines".. unless they have a computer smart enough to retard the timing far enough to reduce the knock. It's not that some engines do not try to reduce the ignition timing, it's just outside their range of opperation.. Thus premium only. BMW allows for down to 89 octane (the computer and timing range is there), but most Detroit iron, has not bothered to include such a range.
    Any gas available above 93 octane is generally considered "race" gas and has to be pumped out of 55 gallon drums in back, and at a increased price of near $5/ gallon. (unless you have access to an airport that has pump "aviation" gas. I have only found one unleaded "race" gas, that is at Union 76, it is 100 octane. The Union 76 station sold 105 and 110 octane gas, but it was leaded and therefore DO NOT put it in your BMW. Unless of course you like changing out your CATs.


  6. #6
    Registered Member
    Location
    Harrison Township, MI, United States
    Member No: 32141 kowached is an unknown quantity at this point kowached's Avatar
    Join Date
    Apr 2002
    Posts
    11,713
    Rep Power
    0


    Yes | No

    93 & 94 Octane is Premium in MI, $1.65ish/gal.



    Later,
    Dave

    For a great guide to E39 online resources, answers to many common questions, and help that will you get started out on the right foot here at Roadfly, check out the Unofficial Roadfly Welcome Package.

    E39 - 1998 540iA Sport (11/97 Production)
    E30 - 1989 M3 (44k miles)
    1979 Triumph TR7, still have my first car ;-)
    Past cars:
    E21 - 1980 320i (sold at 130k)
    E23 - 1986 735i
    Proud to be a Roadfly Inner Circle member (Member #32141).
    I am a BMW Car Club of America member (#111247), are you?



    Is it the new blues mobile or what? (original movie wav)

  7. #7
    Gregory528iT
    Guest
    Location
    , ,
    Member No: Gregory528iT's Avatar


    Yes | No

    Wow, you get 94....

    The guys in CA. SD. and other states will be jealous. They only have 91 max. Of course, each rating is the specific State's own number. So 92 WA, might be similar to 93-94 MI.
    Look at the octane rating sticker on the pump.. it's a state specific formulation and state signed off. Not a federal standard.

  8. #8
    Registered Member
    Location
    Harrison Township, MI, United States
    Member No: 32141 kowached is an unknown quantity at this point kowached's Avatar
    Join Date
    Apr 2002
    Posts
    11,713
    Rep Power
    0


    Yes | No

    I bet all stations use R+M/2 method

    Look at the sticker on the pump the next time that you fill up, I bet that the octane is calculated the same way as it is in the mid-west, I do not believe that the calculation varies by State. The pump octane is also referred to as the Anti-Knock Index (AKI). AKI is determined based on an average of the Research Octane Number (RON) and the Motor Octane Number (MON). The formula is RON+MON/2 normally abbreviated as R+M/2 on the pump.

    Sunoco is the only station that has 94 Octane premium around here, "Highest Octane Under The Sun" is their slogan. Everyone else pretty much has 93 octane.

    Later,
    Dave

    For a great guide to E39 online resources, answers to many common questions, and help that will you get started out on the right foot here at Roadfly, check out the Unofficial Roadfly Welcome Package.

    E39 - 1998 540iA Sport (11/97 Production)
    E30 - 1989 M3 (44k miles)
    1979 Triumph TR7, still have my first car ;-)
    Past cars:
    E21 - 1980 320i (sold at 130k)
    E23 - 1986 735i
    Proud to be a Roadfly Inner Circle member (Member #32141).
    I am a BMW Car Club of America member (#111247), are you?



    Is it the new blues mobile or what? (original movie wav)

  9. #9
    Registered Member
    Location
    , MA, United States
    Member No: 17124 MarkOC is an unknown quantity at this point MarkOC's Avatar
    Join Date
    Nov 2001
    Posts
    11,083
    Rep Power
    0


    Yes | No

    Same in Mass


  10. #10
    Bad Email Address on File
    Location
    Sterling, VA, United States
    Member No: 69172 johnodrake is an unknown quantity at this point johnodrake's Avatar
    Join Date
    Mar 2003
    Posts
    10,967
    Rep Power
    0


    Yes | No

    Minor technical point -

    The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites (as opposed to resistance to combustion). When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine

    2000 540iA Sport Titanium Silver/Gray Dinan CAI, AFM, TB Stage4 and Tranny Software
    1997 'Vette LPE SC Sebring Silver/Black
    1981 Mooney/ Red White and Blue

  11. #11
    Bad Email Address on File
    Location
    Sterling, VA, United States
    Member No: 69172 johnodrake is an unknown quantity at this point johnodrake's Avatar
    Join Date
    Mar 2003
    Posts
    10,967
    Rep Power
    0


    Yes | No

    Don\'t use AV GAS with Cat Converter

    100 and 100LL still has lead in it. (This leaded fuel will disappear in a few more years as there are only two refineries making it now. All Piston AC will then have to use unleaded fuel. It isn\'t so much an issue of compression but one of Valve Seat lubrication.)

    2000 540iA Sport Titanium Silver/Gray Dinan CAI, AFM, TB Stage4 and Tranny Software
    1997 'Vette LPE SC Sebring Silver/Black
    1981 Mooney/ Red White and Blue

  12. #12
    User Level 8
    Location
    Everett, WA, United States
    Member No: 32419 gregory528iT is an unknown quantity at this point gregory528iT's Avatar
    Join Date
    Apr 2002
    Posts
    12,254
    Rep Power
    0


    Yes | No

    Maybe it's just California?

    You are right. that is the calculation I remember seeing. I have heard of California having it's own special low emmsions blend.
    I did notice that is was a state certification, not a federal one.

    Yeah, I'd be stopping at the Sunoco all the time, if I could get 94 especially at $1.65/gal.




+ Reply to Thread


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

     

Bookmarks

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
1e2 Forum