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  1. #1

    Premium vs. Regular Unleaded

    I'll be picking up my JX in a couple of weeks, and I noticed the manual says "premium fuel recommended". The manual for our current vehicle says "for optimum performance, use premium fuel", but we have been using 87 octane exclusively for the last two years with no issues. I already found out it won't void the warranty by using regular unleaded, but I'd like to get some thoughts from any current owners if they are using regular or premium and if they notice any difference in performance. Obviously, the way gas prices are right now, I'd like to get away with using regular if I can, But I will bite the bullet and use premium if I find that it is measurably better for the vehicle. Thanks

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  3. #2
    I use the premium, if your spending over a $50,000 for a car might as well put the best possible fuel in it! I personally don't want to take a chance by the regular fuel doing any damage so I use the premium.

  4. #3
    The high performance of Nissan engines used in Infiniti have a high compression ratio. Using premium (high octane) fuel allows it to operate in its mid-bell curve. The fuels sensors once detecting a lower octane fuel will set its computer setting to retard-delay the timing of ignition to prevent knocking at that compression ratio. Hence, at that setting, the operation is not at its mid-bell curve. I just don't know at what level of engine running demands will that "outside-of-the-mid-bell-curve" show knocking, lower output, etc. when regular 87 octane fuel is used. I would strongly opine to use premuim high octane fuel for this reason.

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  6. #4
    It'll work with a lower grade but it's not healthy for the engine. If the engine was tuned for premium then it should be using premium. It can use regular in an emergency but it's not recommended. Use premium and your car will last longer.

  7. #5
    Dealer said you can use regular instead of premium. You lose 6 horsepower.

    Mine is a 36 month lease so I could give a sh$t about lasting longer. I guess this is for a different thread but with over 60 % residual I don't understand why you would purchase instead of lease? But I always lease.

  8. #6
    Use the fuel in between. If recommended is 91 octane then you can try using 89. 87 might be too low, car will run shitty.

  9. #7
    When I test drove the JX, we had to stop off at a gas station for more gas. I was surprised to see that the salesman used 87. He said that it was corporate policy for their Infiniti dealerships to use 87 on all of the Infinitis on their lot!

  10. #8
    Anyone read the manual? Talks about using 87 in the rare occasion you can't get 91. And that too, it advises you to fill upto half a tank for emergency.

  11. #9
    As G37X-JX35 stated above, the engine will automatically compensate for the fuel grade you buy. High octane does NOT equate to quality. It's one of the biggest myths running, right up there with the 3k/3m oil change.

    The ONLY change you'll see is a small hit to economy. There is no harm to the engine.

  12. #10
    Only reason for premium is to minimize detonation given the high compression. If the sensors detect any detonation, it automatically pulls timing thus losing some HP (minimal). There's no octane sensor on the vehicle btw, if it makes you feel more comfortable use premium during hotter months (if in hot climate region).

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