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07-24-2010, 08:40 PM | #26 |
Scooby Newbie
Member#: 252281
Join Date: Jul 2010
Chapter/Region:
E. Canada
Location: Montreal Quebec Canadaland
Vehicle:2007 Impreza |
Used 87 when I drove it home and it was terrible. Even my friend who was in the car could hear it. I filled up with 91 and I swear about 3km's later not only did the car sound better but it felt smoother and had a tad more kick.
I checked the owners manual expecting to find a min rating of 89 but it was listed at 87..
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07-24-2010, 08:57 PM | #27 | |
Scooby Guru
Member#: 134005
Join Date: Dec 2006
Chapter/Region:
MAIC
Location: Pittsburgh, PA
Vehicle:2004 WRX Premium PSM |
Quote:
It's 10 cents more. I don't like hearing it, so it's worth it for me. Still interested in where to get the 'best' gas at. We had Sheetz all over the place here and only a few Sunoco. I know Sheetz offers the best prices by buying from whoever's cheapest at the time. That's probably a bad thing, but I haven't had a problem with their product... knock on wood. |
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07-24-2010, 10:44 PM | #28 |
Scooby Specialist
Member#: 94299
Join Date: Aug 2005
Chapter/Region:
Tri-State
Vehicle:2000 2.5 RS Sedan SRP |
In my area on LI, NY I feel HESS and MOBILE have the best gas but yet again, how can we truly know.
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07-24-2010, 11:58 PM | #29 |
Scooby Newbie
Member#: 220808
Join Date: Aug 2009
Chapter/Region:
AKIC
Location: SoCal
Vehicle:2005 WRX Wagon Silver |
i have an 06' 2.5i and put 91 octane in it. runs perfectly. someone said earlier about the risk of deposits building using the higher octane, and i wonder if this is the case of a whistling sound out the tail pipe of my car during medium heavy load in direct correlation to a turbo spooling. Definitely sounds like a dirty exhaust system to me and can almost feel the restriction anyone have any ideas on that?. However, to respond to the actual topic of this thread, i definitely notice the difference between say "Thrifty Gas Stations" and Chevron. I dont feel any difference in performance, but the thrifty gas would burn much quickly or something cause i would be filling up more often than using chevron gas. that was also when i drove a pontiac grand am gt that couldnt pass a smog test lol
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07-25-2010, 12:09 PM | #30 | |
Scooby Specialist
Member#: 192599
Join Date: Oct 2008
Chapter/Region:
MAIC
Location: Reading, PA
Vehicle:2004 STI 2007 Outback Wagon |
Quote:
(does anyone else have a Turkey Hill minimart in their state? i found it humorous they are on the list, but not Sunoco USA) I use 89 in my Outback. When I run 87 I get 23 mpg. And when I run 89 I get 27mpg. Price paid to miles saves me roughly $5+ a tank. Never tried running anything higher. Maybe one day when the prices are a bit low I'll try it. |
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07-25-2010, 03:05 PM | #31 | |
Scooby Guru
Member#: 134005
Join Date: Dec 2006
Chapter/Region:
MAIC
Location: Pittsburgh, PA
Vehicle:2004 WRX Premium PSM |
Quote:
Ditto... on the gas mileage increase too. I've tested using the same pump in various conditions and 89 is the best bang for the buck for me. Roughly +2 or +3 MPG more with 89. Anything higher, like 93 is 40 cents more than 87. 89 is only 10 cents more. I can't justify 40 cents more... but I haven't done the testing. I'd find it hard to believe it would net comparable gains for the extra cost. |
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07-25-2010, 06:48 PM | #32 |
Scooby Guru
Member#: 137398
Join Date: Jan 2007
Chapter/Region:
E. Canada
Location: Toronto
Vehicle:2004 Impreza |
I've always used Sunoco or Shell whenever I needed gas. I only run 87 although I did experiment with 89, 91, and 94 and found any difference that would justify spending more for the premium octanes.
The Sunocos are being converted to Petro Canadas due to a merger or whatever but I typically fill up at the station near my house. |
07-25-2010, 07:15 PM | #33 | |
Scooby Newbie
Member#: 141433
Join Date: Feb 2007
Chapter/Region:
MAIC
Location: Rochester, NY
Vehicle:2006 Impreza 2.5i Obsidian Black |
Quote:
Agreed. The recommended octane for our cars are what Subaru designs them to use. A 2.5i is tuned for using 87 octane fuel. |
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07-25-2010, 07:23 PM | #34 |
Scooby Newbie
Member#: 141433
Join Date: Feb 2007
Chapter/Region:
MAIC
Location: Rochester, NY
Vehicle:2006 Impreza 2.5i Obsidian Black |
I always track my gas mileage and I have made the decision to stick with Sunoco. I used to fill up with Hess for 2-1/2 years because of the convenience of location, but when I moved last year and Sunoco became my fill up spot I noticed a 1-2 mpg increase on a consistent basis. With my old 99 legacy GT I went from 22-23 summer to 24-25. My 06 2.5i was getting 24-25 when I first got it, but now since I have completely switched to Sunoco I am averaging over 26 for the last 4 months.
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07-26-2010, 08:08 PM | #35 |
Scooby Specialist
Member#: 168129
Join Date: Jan 2008
Chapter/Region:
SCIC
Location: High Desert
Vehicle:2013 WRX WRBP |
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07-26-2010, 09:45 PM | #36 |
Scooby Specialist
Member#: 220259
Join Date: Aug 2009
Chapter/Region:
MAIC
Location: HoCo & College Park
Vehicle:09 2.5i SSM |
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07-26-2010, 10:37 PM | #37 |
Scooby Specialist
Member#: 168129
Join Date: Jan 2008
Chapter/Region:
SCIC
Location: High Desert
Vehicle:2013 WRX WRBP |
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07-26-2010, 11:00 PM | #38 | |
Scooby Newbie
Member#: 212003
Join Date: May 2009
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Quote:
It's not a limitation of the gasoline, it is however a limitation of the tuning. We can probably get an open tune map that would take better advantage of higher octane fuel. Subaru doesn't recommend it on THIS tune. And thus that is what is 'best' for our car at this time. I'm still obliged to think that running higher octane gas on our cars with our factory map won't do us any good, if not cause carbon build up. No one has directly evidenced how my mechanics suggestion was incorrect. Not that I take it as a fact, but right now I'm trusting the guy who works on subarus for a living for over 20 years, over you lot. |
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07-26-2010, 11:53 PM | #39 |
Scooby Specialist
Member#: 220259
Join Date: Aug 2009
Chapter/Region:
MAIC
Location: HoCo & College Park
Vehicle:09 2.5i SSM |
You keep on running 93 octane on your stock car and experience your false placebo effects (I swear it runs smoother!), I'll keep to my 87 and save myself money.
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07-27-2010, 12:27 AM | #40 |
Scooby Guru
Member#: 60082
Join Date: Apr 2004
Chapter/Region:
MWSOC
Location: Minnesota
Vehicle:2004 Forester STI Silver |
The tune is designed to run on 87 octane. You put 87 octane in and it drives exactly as designed. You can put in whatever octane you want. If the ECU is tuned and is not very adaptive, it will not do anything useful with the higher octane. If you want to run 91 octane and actually see an advantage (a) the ECU needs to be designed to advance timing...a lot...stock or (b) retune the ECU to take advantage of the slower burn and resistance to knock. Not many cars are designed to tune excessively automatically because they don't expect you to run higher octane in the car. I'll give an example. I've run both I-Speed's SRS-10 and SRS-20 flashes. The SRS-20 tune runs just about double the timing of the SRS-10 flash making use of the change from 87 to 91 octane. The gain for this yields around 5 ft-lbs. One, do you think a completely stock ECU will advance timing that much if you just toss in higher octane on a bone stock engine? Two, how much gains do you really expect from the change?
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07-27-2010, 12:56 AM | #41 | ||
Scooby Specialist
Member#: 168129
Join Date: Jan 2008
Chapter/Region:
SCIC
Location: High Desert
Vehicle:2013 WRX WRBP |
Quote:
Our ECU's go through a process of learning where they can advance the timing, and where it has to pull the timing. Depending on conditions, it adjusts timing using course adjustments (the infamous IAM value which effects ALL RPM's), a somewhat middle of the road adjustment, and a fine adjustment. If atmospheric conditions change, and the knock sensor starts sending **** tons of knock signal to the ECU, it will change the IAM, which throws ALL of the other adjustments out the window, and it has to relearn them. It also constantly plays with the fine adjustment, slightly advancing the timing here and there to see if it will get knock, to keep the engine on the very edge of knock - for emissions and power. ____________________________ _______________ Exhibit A: Quote:
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07-27-2010, 02:31 AM | #42 | |
Scooby Newbie
Member#: 212003
Join Date: May 2009
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Quote:
I wasn't really debating that it couldn't be 'good' in some cases anyway. (I will debate that it's good in 'every case' however.) I posted mostly to insert what my mechanic said in light of the 'higher octane is always better' argument that came along. Everyone has seemed to ignore it for the higher octane love in. /whatever, it's your car, your money, ruin it however you like. |
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07-27-2010, 04:23 AM | #43 |
Scooby Newbie
Member#: 149724
Join Date: May 2007
Chapter/Region:
W. Canada
Location: Calgary Alberta, Canada
Vehicle:1999 leggy gt 5speed Blood red |
(now where is the big one of those)
Anyways : With a stock motor and after putting in 91 octane shell v power, in Calgary (3500 ft above sea level, it would therefor = about 94 octane at sea level) I still see knock. So it is not a "Hardware issue" and I can direct you to the tuner and logger I use, it is also not a problem for the "software" to compensate for the higher octane. The problem then becomes ??? Cheap ass bastards who refuse to log, dyno tune or have a uncalibrated butt dyno and just can't tell the difference. I am not recommending anything other then what ever you want to put in your car, but for me I get 42mpg with 91 octane, and 31ish with 87. Ps. To all you carbon buildup fanbois. When was the last time you pulled apart some heads and can prove high octane gas caused more carbon buildup then regular ( I want pictures) And who is to say it isn't anyone of a 100 other factors like lugging or babying or cold weather or old plugs or winter gas or clogged air filters or oil blow by or... |
07-27-2010, 07:02 AM | #44 |
Scooby Specialist
Member#: 192599
Join Date: Oct 2008
Chapter/Region:
MAIC
Location: Reading, PA
Vehicle:2004 STI 2007 Outback Wagon |
Yea, my manual says MINIMUM 87. Also on 87 my OBW has a stupid hiccup on a quick launch. 89 and it's gone. Motor is healthy, tune up parts are new. (Maybe the dumb DBW?) It just likes 89 better. But whatever.
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07-27-2010, 08:20 AM | #45 |
Scooby Specialist
Member#: 38222
Join Date: Jun 2003
Chapter/Region:
Tri-State
Location: Cicero, NY
Vehicle:'10 &'12 Foresters another Miata convert |
What does "Minimum 87" mean, exactly?
It obviously says that 85 is out of the question, but what does it say about 89+? Is it just also safe to use? Does it imply that there's more of any sort of performance if you prefer filet mignon over PB&J? Actually, NO. Let's not read words that aren't written. We're certain of the reason to not use less than a given octane, but a lot of posts here seem to follow a lot of hearsay and hypotheses. Science shouldn't be so polarized. Thanks to everybody who does legitimate testing (datalogging, tracking fuel economy over a number of tanks rather than quoting their best or worst, real dynos instead of butt dynos, etc.) |
07-27-2010, 09:58 AM | #46 | ||
Scooby Guru
Member#: 141373
Join Date: Feb 2007
Chapter/Region:
E. Canada
Location: Quebec, QC
Vehicle:2022 Crosstrek Sport 6MT |
Quote:
Quote:
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07-27-2010, 10:19 AM | #47 | |
Scooby Specialist
Member#: 134262
Join Date: Dec 2006
Location: Hoenix
Vehicle:-1 centrifugal bumble-puppy |
Quote:
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07-27-2010, 11:45 AM | #48 | |
Scooby Newbie
Member#: 212003
Join Date: May 2009
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Quote:
Post your logs, your graphs, your dynos, your regimented logged gas mileage (more than just one tank worth of data) yourself and quit being daft. Hey everyone, apparently the Mechanic that's been servicing Subaru's for 20+ years professionally is just full of crap and has absolutely no clue what he's talking about when he told me that higher octane has been found to lead to carbon build up *in some cases* in otherwise normally operating engines designed for 87. I don't normally trust mechanics as far as I could throw them, but trusting him or trusting the butt dyno subject matter experts after 2 pages of some random thread on this site.. - I'm picking him. And if you want butt dyno results to count - I ran 89 octane in my '03 legacy for half of the 3 years I owned it. My mileage did not increase, the car did not run better, have more power or any of that. When I got my Impreza I tried it again, to the exact same result. My mileage did not increase, there was no more power. It ran pretty much exactly the same. *SHRUG* It reminds me of one of those idiot labels you see on some products advertised to make you stronger / lose more weight etc etc... "RESULTS MAY VARY" For me, the only result was making my wallet lighter. Sorry if that shatters the reality you've built for yourselves but like I said, Your car, your money, ruin it however you want. Last edited by Imp-RS; 07-27-2010 at 11:50 AM. |
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07-27-2010, 12:08 PM | #49 |
Scooby Specialist
Member#: 38222
Join Date: Jun 2003
Chapter/Region:
Tri-State
Location: Cicero, NY
Vehicle:'10 &'12 Foresters another Miata convert |
Holy crap! That's exactly what I said in the next few lines of my post! C'mon, don't be that guy.
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07-27-2010, 12:10 PM | #50 | |
Scooby Newbie
Member#: 194081
Join Date: Nov 2008
Chapter/Region:
W. Canada
Location: Winnipeg, MB
Vehicle:2005 Legacy Ltd. Wag Royal Blue Pearl |
Quote:
That being said, I agree that higher octane will offer zero benefit if the engine doesn't need it. |
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