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Is there such a thing as too much octane? '96 4.6L LX Seafoam

Discussion in '1967 - 1988 Ford Thunderbird' started by Leannadanna, Jul 5, 2017.

  1. Hi!

    I have a '96 4.6L LX. Despite using high quality (Chevron) premium octane (91) fuel, as well as checking the oil regularly, my car makes an audible tapping noise and gets a little sluggish when accelerating from 2nd to 3rd.

    I've been experimenting with octane booster, first with regular (87) unleaded, and more recently with premium. When added to the regular, it made no difference. But when I added it to the premium, it was like driving a different car... powerful with zero hesitation or knocking.

    I don't mind paying for the booster if it makes that much of a difference, but I can't help but wonder two things: 1) is there a bigger problem somewhere?
    2) is there such a thing as "too much" octane?

    Thanks for your time!

  2. tbird

    tbird Super Moderator Staff Member

    You should always use what octane your car calls for unless you have a custom tune for a higher octane. With that said, when you run tunes, they tell you that you have to use AT LEAST the octane your car is tuned for or HIGHER. Unless the car is tuned with a computer tuner, you are wasting money putting higher octane in it.
    sonnysixkiller and Leannadanna like this.
  3. Thank you so much. That makes perfect sense. Still, then, I have to wonder why it runs better with more...it isn't my imagination.
  4. captrick

    captrick Active Member Lifetime Donor

    There could be a number of reasons why it runs better with higher octane. One reason could be is that now you are getting a better air to fuel mixer, which translate to possible weak injectors or even a build up of carbon in the throttle body or in the cylinders. Try a good fuel system cleaner for a few tank full's. I always have had good luck with Seafoam fuel treatments. They have the spray for the throttle body and intake area and the liquid for the fuel tank. It might take a number of treatments but it will do the job. Good Luck Rick
    Leannadanna likes this.
  5. Rick...thank you. I will do as you advised and see what happens.

    Your suggestion leads me to 2 other questions.

    When I first started driving her, I ran a couple of bottles of fuel injector cleaner through and it actually seemed to make it worse. I mentioned it to a mechanic friend of mine and he said it's possible to do "too much" cleansing, as in I could be drudging up more "junk" than necessary. The car had been parked for 2 years without being started or driven. So my first question is this: Is there any validity to his theory? I assume there is a difference between straight "fuel injector cleaner" and "fuel system cleaner". Maybe that was part of the problem.

    My second question is this: Is it safe to run a bottle of system cleaner "good for up to 20 gallons" through a half-full tank? I can RARELY afford to fill her up. If that's a no-no, I could just use half a bottle but the stuff is flammable so I don't think I would want to hold on to the remainder. Would I? Lol...

    Thanks so much!
  6. captrick

    captrick Active Member Lifetime Donor

    You failed to mention that the car sat for two years. The ethanol in the gas collects water from the air and acts like condensation in the fuel system. Try the Seafoam I mentioned earlier on a fresh tank of gas. Also gas loses it octane rating as it sits in the tank and is subject to air. Bite the bullet and run the tank almost empty put the seafoam in for the next 3 tank fulls and you will see the difference. Good Luck Rick
    Leannadanna likes this.
  7. Hi Rick!

    I'm sorry it has been a while since you advised. I had not forgotten. Honestly, I can't usually afford to even come close to filling my tank, which is why it took so long >.< But I DID follow the directions on the Sea Foam carefully, made sure the product:fuel ratio was exact.

    Lol I ran it to the last drop. Also, you suggested driving fast for a distance while the stuff was in the tank. I did that, too...nothing spectacular but 75mph for a good 20 miles. She didn't start running better right away.

    I followed up with 3/4 of a tank of premium, no additives or octane booster, and about 30 miles in I could DEFINITELY tell a HUGE difference for the better. Literally...driving is pure joy...no hesitation, smooth power, no knocking. Now she purrs AND she has balls!

    I intend to do it again soon. Just want you to know your advice was solid and not received in vain. Greatly appreciated!

  8. captrick

    captrick Active Member Lifetime Donor

    I am glad it only took a good fuel additive to cure your problem. If you use Seafoam on a regular basis it keeps everything clean an running smooth. I am glad it worked out for you Rick...........
    Leannadanna likes this.
  9. tbird

    tbird Super Moderator Staff Member

    Leannadanna likes this.
  10. I have tried other fuel additives over the past year with no noticeable improvement. I am now a firm believer in SeaFoam!!!
    tbird likes this.

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