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Discussion Starter #1
Ok im back and yes this time with a minor (i hope) problem.

My dad has been barrowing my z and i forgot to let him know what gas to put in her. she has only had cheveron 91 octane gas since day 1.

he put in costco 87 octane gas in her. now i caught it half way through the first tank.

what kind of problems could this have caused, and what do i do now? just fill her up with the correct grade? put something supplemental in it?
 

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It's only an NA. If it were a TT, I'd say top it off with 100 octane, but since it's an NA, I'd baby it until that tank is gone, and resume your normal gas. You can probably notice a difference yourself, but being an NA, it's probably not going to hurt anything.
 

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I don't think it would be a noticeable difference in either car unless you're driving it hard. Its not like the car's gonna start detonating while cruising at 45 mph or sitting at a stoplight. Now when hard accelerating or WOT. . .then you will have issues.
 

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Hence why we have a detonation sensor and computer controlled ignition. Your car will retard timing accordingly, via the sensor sending det. information to the computer. It will compensate for the 87 in it, you shouldn't have a problem.
 

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Discussion Starter #5
cache thanks a lot, that answered my next question.

yesterday when starting (this is the only time it did this) the first turn of the key tried to start for a second, and then the second it started with out a problem.


should i use all of this gas up before putting in the higher octane or just put it in now?
 

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I'd run it down about half a tank, then fill it up with the highest you can buy in your area (I can get 104 down the road, but it's $$$$). Then run that down. But that's just me.

I like spoiling my cars.
 

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I don't know about going as high as 100+ octane. Just put in the highest premium gas you can get. Usually it's somewhere between 91-93 depending on your state and area. Just fill it up with some 91 and run the tank down to near empty. By doing this you'll get a mix between the 87 and 91 which should be somewhere about 89 octane assuming you have half a tank of 87 and fill up the rest of the tank with 91. At that point just go back to 91 and you'll be fine. As others mentioned it's a non turbo so it's not that big of a deal.
 

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ah ****, why not just buy some avgas at 110 octane, lol. Quit worrying about it, get gas when you need gas and go back to premium.
 

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sigh. An NA has a pretty high compression ration. I would not be as relaxed as the rest of the people on these forums. it's not "just an NA" it IS a car with a 10.5:1 compression ratio tuned for 91 octain with a detonation map that is not conservative enough IMO.

Your probably all right but just use as little throttle as possible especally at low RPM where detonation is more likely. Get some touline or racing fuel too, if you can.
 

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I'd say you'd be fine on the 87 if your running smooth and not pushing the car. Go until the tank is almost empty and then just fill it full with your 91 like you were running.

If you are that worried about it though while your running on the 87, you can throw in one of those octane boosters but I would say you would be fine without it and just go back to what you were running.
 

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just a question, how would it run with lower octane gas and running the car hard?
 

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Yes... it could make a difference, especially in the NA, if you are lugging the engine! Remember, the NA has a high compression ratio! Top the tank off with high octane.


-MAS
 

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Takahashi is right. the NA engine may predetonate with the cheaper gas in it.

i made that mistake when i first bought my Z.even driving easily,it would ping.
 

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Just top off now with the highest octane gas you can get. When you get to 1/2 tank again, then top it off again. Stay out of the throttle and don't lug the engine. Like it was stated before... The NA engine is just as prone, if not more so, to detonate as the TT using 87 octane. If you haven't noticed any problems so far, then I wouldn't worry about any "damage" that's been created. If there was any damage done, then you'd know it.
 

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Right after Katrina, I ran 87 and 89 due to shortages in NC, no problems if your knock sensor is working. The fuel map will adjust to low octane, you will feel the difference in performance.

Switch back to 91 it takes 2 or 3 starts to remap the fuel.

No ill effects.

Good luck,

Glen
78 280Z
94 300ZX 2+2
 

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I've known a couple people [older gentleman/women] that ran only 89 octane for the lifetime of their n/a z without problems. They also lived in coolor climates and didn't push their car very hard. I also knew a kid that drove the **** out of his car and though anything about 87 was a waste of money. He'd add a gallon or two of premium if he was going 'racing'. He also had no problems. However, as mentioned, the n/a engine with its higher compression ratio is at higher risk for detonation at lower rpms. Just drive the car easy and put in premium as you go.
 

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As mentioned, just get a can of Octane Boost at the local car store. My wife does this every so often (by accident) on her Maxima - I know the drill well!
 
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