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Old 02-23-2008, 07:09 AM   #1
Nicky B.
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Default 2.5i with 92 oct.

Many people have said do no use anything Higher than 87 oct. After reading the manual, we should not be afraid of higher octane. the manual states " the 2.5L non-turbo engine is designed to operate using unleaded gasoline with an octane rating of 87 AKI OR HIGHER. But obviously race gas and high 90 octane is absurd
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Old 02-23-2008, 08:29 AM   #2
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with gas prices the way they are, I don't know why you would want to put anything more than 87 octane in a n/a car that calls for 87 octane. I definitely wouldn't be afraid of it but i won't waste my money on it either. unless you have a chip or a cam or some other modification that requires you to boost your octane you're wasting your money.
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Old 02-23-2008, 10:25 AM   #3
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it might make it run smoother, but I've tried 89 and 91 longterm in the winter to see if I could improve winter mileage... it works... but you don't get the improvement that justifies the extra 10-15 bucks or more per tank.
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Old 02-23-2008, 11:10 AM   #4
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The only time I would use it is if it gave me more mileage than 87 but then I'd have to factor in how much I'm paying per tank.
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Old 02-23-2008, 12:42 PM   #5
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Quote:
Originally Posted by Sir-Knight View Post
it might make it run smoother, but I've tried 89 and 91 longterm in the winter to see if I could improve winter mileage... it works... but you don't get the improvement that justifies the extra 10-15 bucks or more per tank.
What are you filling up? No Subaru, that's for sure.

It's more like $1.20-$2.40.
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Old 02-23-2008, 01:02 PM   #6
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55 L on a fillup... 1.10$/L where I live for 87, 1.25/L for 94 octane
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Old 02-23-2008, 01:03 PM   #7
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okay, so it's closer to 6-7$ a tank, but you don't get 6-7$ in savings per tank with the increased efficency.

lulz the edit button broke
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Old 02-23-2008, 02:43 PM   #8
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Why WOULD you want to? That is one of the glory of a NA subie, 87 octane!

It isn't like raising the temperature for the gasoline to ignite is going to help your car out.
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Old 02-23-2008, 05:03 PM   #9
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i have used both 87 89 octane and i beleive that the car runs better on 87. so im not sure if just dumping 92 into a 2.5i would yeild any results, but if you TUNED to a higher octane, im sure there could be benifits.
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Old 02-23-2008, 05:55 PM   #10
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yea its definitely not a $15 dollar difference. For me, 6 bucks extra a tank is not a big deal. I just switched to 92, i'm going to give it 3-4 tanks then see if I can notice any difference, if not i'll go down to 89. I just can't justify putting 87 in my car when most of the world doesn't even sell gas with that low of octane. Its all personal preference thought.

Last edited by Nicky B.; 02-23-2008 at 06:02 PM.
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Old 02-23-2008, 07:26 PM   #11
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Recently I started getting 20 miles less a tank than I used to I raised the octane and I started getting 300 again.
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Old 02-23-2008, 07:34 PM   #12
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Quote:
Originally Posted by Nicky B. View Post
yea its definitely not a $15 dollar difference. For me, 6 bucks extra a tank is not a big deal. I just switched to 92, i'm going to give it 3-4 tanks then see if I can notice any difference, if not i'll go down to 89. I just can't justify putting 87 in my car when most of the world doesn't even sell gas with that low of octane. Its all personal preference thought.
I think you ought to look up octane on wikipedia.

North America uses the AKI (anti knock index) instead of a true octane rating(RON). In fact our 87 is the equivalent of the lowest grade fuels elsewhere.
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Old 02-23-2008, 10:20 PM   #13
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I use 89 and i think its a waste im just to stupid to go down to 87
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Old 02-24-2008, 01:48 AM   #14
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Unless you have some type of built N/A motor.. like a high compression frankenstein.. using anything over 87 octane is a total and complete waste of money. it is a proven fact that there is no gain.. If your N/A has some type of knock, ping detonation etc to make it run smoother on 91 than 87... and it is not a built motor.. something is wrong with you car..
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Old 02-24-2008, 12:44 PM   #15
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It would actually be hurting your motor unless you beat on it in the summer to use anything higher than 87.

High octane gases are designed to be used in motors than run hotter than your average toyota corolla. Thus they contain additives than allow it to resist igniting at low points in the cylinder. So if you use anything higher than 87 your cylinders are most likely firing more advanced than usual. In turn your motor is working harder along with the ecu freaking out.
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Old 02-24-2008, 01:22 PM   #16
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Let's do the math... Around here in New England, 89 is usually 8 cents more a gallon, and 91-93 is about 15 cents more. Let's round up our tanks to say... 16 gallons. By running 93 octane, even at dead low it would be only 2.40 cents a more to fill up. If you spend 35-40 anyway, what's an extra couple bucks??? If it means better gas mileage, then I say it's worth it. That's just my 2 cents.
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Old 02-24-2008, 02:06 PM   #17
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but it was proven that it does not help in added gas mileage ive seen people actually go from 89 to 87 and say they get better mileage from it
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Old 02-24-2008, 02:18 PM   #18
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^
I can back that one up...
When I use 89, I get a constant 15mpg. But as soon as I go back in 87, my gas mileage went up to 21mpg. Maybe my car wasn't meant to use 89 and the car is rejecting the 89. I'm going to stick with 87 from now onwards.
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Old 02-24-2008, 03:27 PM   #19
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ignorance is taking hold and digging in here.
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Old 02-24-2008, 05:04 PM   #20
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Can anyone credible respond to this???

Ive used 87 octane, and recently have been putting 93 octane in because ive heard it was cleaner

but i could be completely wrong
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Old 02-24-2008, 05:22 PM   #21
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the octane rating has nothing to do with the purity or cleanliness of the fuel. while 93 may be cleaner in the case of some brands, it is not cleaner because it is a higher octane. The octane rating is the fuels ability to resist detonation (burning violently due to a high temp/hotspot or when its not supposed to basically) instead of burning in a nice controlled even flame front in the cylinder. im not credible as far as fuel goes by any means but i promise you that octane has nothing to do with how clean the fuel is.. in fact high octanes are achieved by adding things to the fuel (lead used to be used until the late 70's). some brands may add detergents or a high level of purification when producing their higher octane fuels but i have never heard of that, personally.
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Old 02-25-2008, 01:21 PM   #22
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Hope this helps, please take the time to read this

http://chemistry.about.com/library/w...abyb100401.htm
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Old 02-25-2008, 03:21 PM   #23
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http://en.wikipedia.org/wiki/Octane_rating

Quote:
Regional variations
In many parts of Europe, 95 RON (90-91 AKI) is the minimum available standard (but is called Premium Unleaded), with 97/98 being higher specification (being called Super Unleaded) In Australia, "regular" unleaded fuel is RON 91, "premium" unleaded with RON 95 is widely available, and RON 98 fuel is also reasonably common. Shell sells RON 100 petrol from a small number of service stations, most of which are located in capital cities. In other countries "regular" unleaded gasoline, when available, is sometimes as low as 85 RON (still with the more regular fuel - 95 - and premium around 98 available). In Russia and CIS countries 80 RON (76 AKI) is the minimum available and the standard.


It should be noted that this higher rating seen in Europe is an artifact of a different underlying measuring procedure. In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2.
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Old 03-04-2008, 10:04 PM   #24
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the 07 2.5i ecu is set to run on 87 octane . only way to benifit from higher octane is to tune it in
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