Regular gas vs. premium gas
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HT4100 4.1, 4.5, 4.9 Discussion, Regular gas vs. premium gas in Cadillac Engine Technical Discussion; Ok ive heard a lot of people saying different things about it, but here it goes ive read that u ...
  1. #1
    Dew Barfer's Avatar
    Dew Barfer is offline Cadillac Owners Member
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    Regular gas vs. premium gas

    Ok ive heard a lot of people saying different things about it, but here it goes

    ive read that u have to use premium due to the lack of ping sensors and such
    so basiclly my question is, with out changing the timing to efficiently operate on regular gas would it do any long term damage to the engine if i run the lower octaine?? or even running premium every 2nd or 3rd fill-up!?!?!
    not to sound like im b*tching but gas prices r gettin high for workin at kfc taco bell n runnin a 94 sdv

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  3. #2
    peteski is offline Cadillac Owners Enthusiast
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    Re: Regular gas vs. premium gas

    Does your car have a Northstar engine? If yes, you should post this on the Northstar forum.

    I also don't recall seeing enywhere that other Caddy engines (like 4.1, 4.5 or 4.9) need premium gas.
    So, unless the gas gauge says "Premium Fuel Only", you're all set using Regular Gas.

    And if it says "premium", there might be some timing adjustments you can make at the cost of decreased preformance.

    Workin' at KFC, eh? Time to trade in that big-bad-Caddy for a Geo Metro or a Kia!


    Peteski

  4. #3
    N0DIH's Avatar
    N0DIH is offline Cadillac Owners Master
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    Re: Regular gas vs. premium gas

    All 4.9L engines are premium fuel engines.

    Although the FSM states that you can change the timing from 10 degrees to 6 degrees to run 87 octane. This "ability" was intended for people who might live in an area that cannot get premium fuel.

  5. #4
    Ralph's Avatar
    Ralph is offline Cadillac Owners 10000+ Posts
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    Re: Regular gas vs. premium gas

    Yup, there are no knock sensors on my 4.9 so if I use regular or even mid-grade I get knocking. Someone here (a knowledgeable man) once said that in summer it's more important to use the correct octane to prevent ping, but in the winter I might get away with using mid-grade. To play it safe I use premium even though it's almost 4 dollars a gallon!

  6. #5
    Dew Barfer's Avatar
    Dew Barfer is offline Cadillac Owners Member
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    Re: Regular gas vs. premium gas

    well dont see my self gettin rid of my babe any time soon so i guess im just gonna tough out the seas till the gas comes back down thanks guys for the info

  7. #6
    Dew Barfer's Avatar
    Dew Barfer is offline Cadillac Owners Member
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    Re: Regular gas vs. premium gas

    well dont see my self gettin rid of my babe any time soon so i guess im just gonna tough out the seas untill the gas comes back down thanks for the info
    i wanna save money but i dont wunna damage my car <=== this out weighs the other

    thanks guys


    sory bout the double post

  8. #7
    gdwriter's Avatar
    gdwriter is offline Cadillac Owners 10000+ Posts
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    Re: Regular gas vs. premium gas

    I've run both regular and premium in my '91 DeVille with 200K. Haven't heard any pinging or knocking with regular, even when I've had to step on it. On a couple of occasions, there's been a little dieseling when I first turn off the ignition. Considering I'm spending $40+ every time I fill up, I'm reluctant to spring for premium if my 4.9 liter is running fine on regular.

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