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Old 12-16-2001, 09:03 PM   #1
Rabican
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Default Recomended Gas for 99 RS 2.5

What type of gas does a impreza 2.5 RS take, i dont have an impreza yet but i think an average of 22mpg is terrible... so i was wondering if it took the highest octain gas or average
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Old 12-16-2001, 10:08 PM   #2
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It's recommended that you put in 89 by Subrau IIRC. Higher octane gas does not necessarily equal better gas mileage however .

Brian
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Old 12-17-2001, 10:24 AM   #3
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I always run 93 octane. Your gas mileage just depends how you drive and where you drive. I only drive like 5 miles a day to work and get terrible mileage (around 22mpg). Last fall i went for a road trip down through NC on the blue ridge parkway,( 45 mph for 250 miles, and got close to 33 mpg IIRC.)

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Old 12-17-2001, 10:28 AM   #4
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Subaru recommends 87 octane.
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Old 12-17-2001, 12:26 PM   #5
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keep in mind, no subaru is a gas miser....... or any AWD car isn't a leader in this category.....

When I go on road trips, I always get over 30mpg.... around my home, I get 26-27mpg.....

Robin
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Old 12-17-2001, 12:44 PM   #6
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running race gas will do absolutely NOTHING for an impreza except superheat the cat. it doesn't matter what you do unless you drive VERY conservatively you are going to get between 18-22 MPG city driving....i get 30-33 on the highway. Well anyhow don't put race gas in it.
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Old 12-17-2001, 01:29 PM   #7
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I would be cautious of Race fuel. In HS my friend had a 1980 cutlas 6cyl, and he decided to fill up and add a whole bottle of ocatine addative (108 ocaatin I beleive for 22 gallons worth) to a 16 gallon tank. THe car went like hell at first you tap the gas it was like a rocket. hour later knock knock next day bam!!! no more engine. Be careful if you go for the super high stuff.


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Old 12-17-2001, 02:26 PM   #8
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I use 87 and get 19mpg around town and got 25mpg on my last road trip. Not very good.
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Old 12-17-2001, 03:42 PM   #9
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sorry thought i read race gas in there somewhere, wow was i tired this morning...just run 87or 89...i run 89 when i know i'll be beating on the car. Just keeps her from pinging and or knocking.

Jeremy
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Old 12-17-2001, 05:16 PM   #10
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for my 00 with 10 to 1 compression ratio

87 in the winter or 0-80F
89 in the summer or 80-110F (87 pings in bog when its hot)

as for a my 99 with 9.7 to 1 i would guess that it would be very simmilar

93 is a waste of $$
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Old 12-18-2001, 04:53 AM   #11
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i run sunoco 87 all the time and i get about 18 to 20 MPH in the city but as of late im getting horrible milage im at a little under a 1/4 tank and i have only gone 190 miles on the other 3/4!!!!!

Nate
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Old 12-18-2001, 10:53 AM   #12
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nate two things ... winter gas...and
is your gas gage screwed up?
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Old 12-18-2001, 11:10 AM   #13
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Heck, the Sube is rated by EPA at 21 city. Unless you put around like grandma you should be happy to see that figure. I know I don't get that in the city, and I don't rip every gear.

After various mileage posts, the average MPG for the RS is what the sticker says, give or take a gallon or two here or there. Commute I get 26-27, when I drive I get 23. It's not an economy car.
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Old 12-18-2001, 11:42 AM   #14
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* check your manual

* choose a gas and stick with it

i have run 89 since day one in my car and i get pretty decent gas mileage!

everyone has their own system tho.
good luck
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Old 12-18-2001, 07:56 PM   #15
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Quote:
Originally posted by Subie Gal
* check your manual

* choose a gas and stick with it

i have run 89 since day one in my car and i get pretty decent gas mileage!

everyone has their own system tho.
good luck
jamie
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I don't think he has the car yet, so it would be kind of hard to check the manual.

Anyway the manual says 87 or higher. Hopefully that will answer the question. So you can use 87, should be no problems.
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Old 12-18-2001, 08:51 PM   #16
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I ALWAYS run 92, since my car has been mysteriously pulling timing between 3400 and 4000 rpm since almost new (now with over 40k). I figure the extra few $s per tank might help.
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Old 12-18-2001, 10:27 PM   #17
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as far as the 2.5 NA block is concerned, it must be bliss to know that some of you are wasting your money on anything higher than 89 octane.

Unless you are running higher than 10:1 compression, you're chipped, or have a FI (or a combination of any of that), there is no need to run a higher octance..

Mileage is the same,
Performance is the same,
It even burns the same.

Save your money and use what the base stuff.
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Old 12-18-2001, 11:14 PM   #18
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I did a lot of sampling on the fuel and fuel mileage 1.5 years ago when I was hacking the stock ECU. Here is what I found.

87 octane in colder weather gives you the best fuel mileage.
89 octane in warmer weather gives you the best fuel mileage.
94 octane plus some 110 octane race gas does give you significant gains, especially if you reset the ECU. These gains are largest in the 5000rpm to redline range.

-Michael
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Old 12-19-2001, 01:09 AM   #19
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Quote:
Originally posted by d00f
I did a lot of sampling on the fuel and fuel mileage 1.5 years ago when I was hacking the stock ECU...These gains are largest in the 5000rpm to redline range.

please explain how you determined mileage for a specific rpm range.

alternatively, explain what you really meant
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Old 12-19-2001, 03:45 AM   #20
lethargicman
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Shell, 89 octane baby!

-Jason SDC
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