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Discussion Starter · #1 ·
Through sheer inattentiveness, I filled up the GTO on mid-grade, 89-octane gasoline this morning.

I'm not sure how I managed this feat, except that the gas station I visited gave this grade some jazzy name that I must've mistaken for premium. My error dawned on me as I was standing there watching the numbers go by and noticed that the price per gallon was a dime cheaper than usual. The tank was almost full by that time, so I just finished up and told myself that, yes, I am a dork.

I guess it's no big deal. I only lost a couple octane points, and I saved myself a dime a gallon. There was no sign of pinging on my commute, either, so that's good. We'll see what happens as I go through the rest of the tank.
 

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I've run mine on mid-grade before with no pinging problems. You can save another dime a gallon with a Discover Platinum gas card. You get 5% back on all gas purchases. I combine that with a local discount I get by showing my work badge and I get premium for about .02 more than regular :cool
 

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Even the owners manual states that mid-grade is fine for the engine but you may lose peak power. Unlike the old days these cars shouldn't ping on lower octane, I'd imagine the knock sensors will retard the timing according and you'll probably not notice.

I myself run 89 octane every few times at the pump just because of gas prices. Unless you're planning on racing you're likely just wasting money for the good stuff. Maybe over the life of the car there could be a downside??
 

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I had this conversation with my father who has worked for GM as a mechanic for over 25 years. 92 octane is recommended but you can run as low as 87 without problems, even in turbo cars. The only thing is you may lose a slight amount of BHP, and if you hear any knocking, its time to go back to 92. Also, mid-grade can actually make the car run better in the cold winter months.

Personally, I only run 92 or higher when I can find. Running 89 will not hurt the car.
 

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filled up yesterday for 1.94 for super

I guess living in NJ has its advantages, I don't pump and pay less. I also read the owners manual on the first day. It said you could run regular if you wanted will no ill affects except accelleration loss. I did not notice a difference but then again I am not at a track comparing times. I do mostly fill with super because of the better quality of gas. Burns cleaner and has detergents in it. It is supposed to be better for your engine besides the higher octane.
 

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You should be fine. The PCM will sense knock and pull timing which will prevent pinging at the cost of power. I believe that if you put 87 in it, it will sense enough knock to go into a set of low octane timing tables, again, lowering power but causing no damage. :cheers
 

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Afterglow said:
I had this conversation with my father who has worked for GM as a mechanic for over 25 years. 92 octane is recommended but you can run as low as 87 without problems, even in turbo cars. The only thing is you may lose a slight amount of BHP, and if you hear any knocking, its time to go back to 92. Also, mid-grade can actually make the car run better in the cold winter months.

Personally, I only run 92 or higher when I can find. Running 89 will not hurt the car.
Thanks. I've seen the debate over 87/98/92 on other boards -- and never jumped in because people wouldn't believe me if I said it. There's actually a Federal law that says cars sold in the United States MUST operate on any grade of gasoline sold.
 

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With as mildly as this engine is tuned from the factory, even 87 is really not a problem. I've had no problems running 87, 89, 91 and 93.
 

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b_a_betterperson said:
Thanks. I've seen the debate over 87/98/92 on other boards -- and never jumped in because people wouldn't believe me if I said it. There's actually a Federal law that says cars sold in the United States MUST operate on any grade of gasoline sold.
That's believable, the manuals for every high end car I've ever seen, always says "Premium Recommended" not Required. Even my roommates 95' 840ci
 

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Discussion Starter · #10 ·
Follow-up

I've put quite a few miles on the car since my fill-up on mid-grade yesterday. I have to say that I don't notice a thing--no pinging, no discernable decrease in power, nothing. If anything's different, it's subtle enough that I can't tell.
 
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