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Thread: Premium gas vs regular

  1. #16
    Dr. Design is offline Banned
    Automobile(s): STS, XLR, STS V-Series, CTS V-Series, XTS....
    Join Date
    Aug 2003
    Design Center

    Re: Premium gas vs regular

    You should certainly try to run 91 or better. If you run 87 in case of emergency it wouldn’t be the end of the world as the computer would compensate for that by pulling timing. However you SHOULD RUN 91 (minimum) at all times if you can do so. Most newer cars have (2) different fuel maps and can change the timing as need be if they sense lower grade fuel. But since you have a high performance vehicle you shouldn’t use anything but premium fuel.

    JenRPh92 -

    You could add an Octane booster of sorts to increase the octane rating. You do not have to drain the gas tank. You can also just be light on the gas pedal and burn up what you have. Again this is not a Major issue for you. Just take caution.

    Thank you,

    Dr. Design
    D3 Cadillac

  2. #17
    CIWS's Avatar
    CIWS is offline Cadillac Owners 10000+ Posts
    Automobile(s): 2015 BMUU 335i MSport, 2006 STS-V--2005 CTS-V ( traded in)
    Join Date
    Dec 2005
    D/FW Tejas

    Re: Premium gas vs regular

    Quote Originally Posted by JenRPh92 View Post
    My husband (who never drives my STS-V) went to the gas station to fill it up for me today and the station was out of premium and was close to being out of regular unleaded due to a gas shortage/panic in our area. He fills it up with regular unleaded and sees no problem with that. I on the other hand had a come apart about it!

    My questions are:
    Would kicking him in the balls be a little too much ?

    From the owner's manual.

    "if your vehicle has the 4.4L V8 engine (VIN Code D),
    use premium unleaded gasoline with a posted
    octane rating of 91 or higher. For best performance, use
    premium unleaded gasoline with a posted octane
    rating of 93. In an emergency, you can use regular
    unleaded gasoline with an octane rating of 87 or higher.
    If 87 octane fuel is used, do not perform any aggressive
    driving maneuvers such as wide open throttle
    applications. You may also hear audible spark knock
    during acceleration. Refill your tank with premium fuel as
    soon as possible to avoid damaging your engine. If
    you are using gasoline rated at 91 octane or higher and
    you hear heavy knocking, your engine needs service."

  3. #18
    JenRPh92's Avatar
    JenRPh92 is offline Cadillac Owners Member
    Automobile(s): '06 STS-V, '87 Grand National, '87 T-Type
    Join Date
    Apr 2008
    Warrior, AL

    Re: Premium gas vs regular

    "Would kicking him in the balls be a little too much ?"

    Ha! That thought did cross my mind! Thanks for the advice/suggestions guys. I think I will stick to getting the octane booster and taking it easy til this tank is used up!

  4. #19
    parttimer is offline Cadillac Owners Member
    Automobile(s): Cadillac
    Join Date
    Sep 2008

    Re: Premium gas vs regular

    Octane boosters really aren't worth what you spend on them. You see the high numbers the bottle say but read the fine print. If you need to use an additive run to the paint store or Lowes and pick up a can of toluene or xylene. When I used to race my Grand Prix GTP I would mix my own race gas with Toluene. Toluene carries an octane rating of 114 and xylen is 117, you would need many many bottles of the off the shelf stuff to equal a gallon of this good stuff!! Do not run this all the time , but if you like to race it may be wise to look into it. I used to mix one gallon of toluene with 4 gallons of gas and some marvel mystery oil for drag days.

  5. #20
    Slo-Mo-Shun's Avatar
    Slo-Mo-Shun is offline Cadillac Owners Fanatic
    Automobile(s): 2006 STS-V; TopKart Flash 125 Shifter
    Join Date
    Jan 2008

    Re: Premium gas vs regular

    If this original poster is getting 21.9 mpg as she stated originally, then she probably does not have a V model and is confused about what car she has. The label on the inside of the fuel cap cover says "premium fuel only." If it doesn't, she's on the wrong forum.

    If it does, then who the heck thinks "only" means "optional"? Tell you hubby that he's risking voiding the warranty and the motor in this car is HAND MADE at the factory and will cost him over 10 grand to replace after he puts holes in the pistons in his short-sighted attempt to save ten bucks. Maybe that will get his attention.
    Last edited by Slo-Mo-Shun; 09-18-08 at 04:44 PM.

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