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Old 05-23-2008, 06:43 PM   #1
Ekeenan86
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Default Improve Your Gas Mileage!!

With the escalating fuel prices I believe a thread is needed on maintenance that can help improve or restore your fuel mileage. Now lets see what people have come up with outside of the obvious repairs (i.e. air filter, fuel filter, routinely changing your oil, ect..) Hopefully if this thread grows it can be put as a sticky, in how this is useful information to every Subaru driver out there.

Include any insight into smaller improvements such as adjusting your tire pressure, or even changing tires to a different tread in order to improve your mpg. Any small improvement will make a large impact over time.
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Old 05-23-2008, 07:21 PM   #2
wrxdrvr
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I have been putting in Acetone in my gas tank for 3 years experimenting how much works the best and came to the conclusion that 1 1/2 oz per tank works the best. Here are my mileage numbers for the last 6 years total average MPG per year;

'02; 21.8 MPG No additive in tank
'03; 22.1 MPG No additive in tank
'04; 21.4 MPG No additive in tank
'05; 22.5 MPG Experiment with 4oz Acetone per tank
'06; 22.8 MPG Experiment with 3oz Acetone per tank
'07; 23.8 MPG Experiment with 1 1/2oz Acetone per tank
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Old 05-23-2008, 07:33 PM   #3
Ekeenan86
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How much do you spend on the Acetone; have you noticed that it was more cost effective to use acetone with the resulting higher mpg?
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Old 05-23-2008, 08:08 PM   #4
wrxdrvr
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I spend about $20 for 3.78L which is about a gallon about 127 Fl oz/1 1/2 per tank equals 84 tanks works out about 23 cents per tank, if my math is right, And I get about 30 Miles better per tank for the 23 cents...
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Old 05-23-2008, 09:00 PM   #5
RoadTrippin
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Suggestions would be great....though honestly Im happy with the 25mpg mixed city/hwy I get along with 31-33 all hwy (all stock parts btw), big improvement over previous vehicles.
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Old 05-24-2008, 09:24 AM   #6
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i ruffly get 30+ on the highway and city i dont know but isnt canadia gas higher in octane? then U.S?
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Old 05-24-2008, 09:48 AM   #7
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Quote:
Originally Posted by wrxdrvr View Post
I have been putting in Acetone in my gas tank for 3 years experimenting how much works the best and came to the conclusion that 1 1/2 oz per tank works the best. Here are my mileage numbers for the last 6 years total average MPG per year;

'02; 21.8 MPG No additive in tank
'03; 22.1 MPG No additive in tank
'04; 21.4 MPG No additive in tank
'05; 22.5 MPG Experiment with 4oz Acetone per tank
'06; 22.8 MPG Experiment with 3oz Acetone per tank
'07; 23.8 MPG Experiment with 1 1/2oz Acetone per tank
that small of a variation could also be accounted for my wearing on the engine. tolerances loosen up, and the engine has lower internal drag.
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Old 05-24-2008, 10:56 AM   #8
wrxdrvr
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Quote:
Originally Posted by rkramer View Post
that small of a variation could also be accounted for my wearing on the engine. tolerances loosen up, and the engine has lower internal drag.
You have a point and I thought of that too. So I skipped the Acetone additive for a few tanks and my mileage went down... Is it scientific enough to pass as a fact, no, but as far as I'm able to determine it does help. A consistent 30 miles per tank more for 23 cents works for me.
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Old 05-24-2008, 11:19 AM   #9
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any negative harmful effects on the engine, injectors, etc with the use of acetone?
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Old 05-24-2008, 12:19 PM   #10
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Take off any roof rack bars / attachments if you're not using them. I see lots of Subarus tooling around with their ski attachments on in the middle of the summer. Sorry, you are not grass skiing, take it off.
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Old 05-24-2008, 12:25 PM   #11
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Originally Posted by nardvark View Post
Take off any roof rack bars / attachments if you're not using them. I see lots of Subarus tooling around with their ski attachments on in the middle of the summer. Sorry, you are not grass skiing, take it off.

Ricers
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Old 05-24-2008, 02:25 PM   #12
wrxdrvr
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Quote:
Originally Posted by SubieRon View Post
any negative harmful effects on the engine, injectors, etc with the use of acetone?
Not that I have found, Instead it seems to run better in the winter (starts easier) and summer (more power). At present my car has 278,000 kms/173,750 Miles with everything still stock nothing fixed or changed on engine and transmission.
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Old 05-24-2008, 06:15 PM   #13
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Quote:
Originally Posted by nardvark View Post
Take off any roof rack bars / attachments if you're not using them. I see lots of Subarus tooling around with their ski attachments on in the middle of the summer. Sorry, you are not grass skiing, take it off.
Truth. Any extra weight is gas saved.
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Old 05-24-2008, 07:09 PM   #14
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I drive a mix between city and freeway. For the last 6 months or so, I have been monitoring my gas mileage closely. When I "fill up" I usually put in half a tank rather than a full tank (less weight). For my half tank 'fill ups' I usually get about 100-110 mi with normal driving.

One thing I was noticing though was that my gas guage was very erratic. For example, if I would take a right turn quickly or apply my brakes down a hill, my gas guage would dip about 1/8 of a tank. So I figured it was buildup on my gas tank floater after 90,000 miles of so cal 91 peewater. I looked for a gas additive that would help to clean my system.

I came upon Lucas Upper Cylinder Lubricant. At first I was skeptical but I was limited in my options for fuel system cleaners. Techron is good, but it is like $15 a bottle and treats 20 gallons of gas.

So I have been using the Lucas product for about 7 'fill ups' and I love it. The bottle costs $10 and treats 100 gallons of fuel. My gas guage problem ceases to exist. The best part by far though, is that I have been consistently getting 125-150 mi out of the same amount of gas I used to get 100-110 out of. All this and I need an oil change badly. Cheers!
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Old 05-25-2008, 12:26 AM   #15
magnum2066
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One trick I use is to only fill halfway. Thats about 80lbs saved in liquid weight.
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Old 05-25-2008, 10:24 AM   #16
mikeythejew
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Have a manual transmission? If so, flooring your car methodically while accelerating can improve mileage. I tried it and got 24 MPG city flooring my car. I'll explain it later on to leave you in disbelief for now.
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Old 05-25-2008, 12:20 PM   #17
magnum2066
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No that doesn't help fuel mileage. The only thing that would give you better mpgs is if you shift early and keep your rpms low. When you step on the gas the turbo tosses more air in which your ecu then injects more fuel to keep the air/fuel ratio correct. Staying out of boost will help you significantly along with shifting at or below 2.5k rpms and staying above 1.5
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Old 05-25-2008, 12:47 PM   #18
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Actually, you would at least theoretically get better mpg by keeping rpms low and opening the throttle wide open or nearly wide open. This is because to do so improves the cycle efficiency of the engine. Computer-controlled engines often don't see this happen because the ECU richens the mixture at high throttle openings. Also, this is called lugging and is generally considered to be bad for an engine.
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Old 05-25-2008, 01:09 PM   #19
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Quote:
Originally Posted by bulwnkl View Post
Also, this is called lugging and is generally considered to be bad for an engine.
What is called lugging? Opening up the throttle to run the engine hard, rather than gradually accelerating?
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Old 05-25-2008, 01:10 PM   #20
wrxdrvr
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Quote:
Originally Posted by mikeythejew View Post
Have a manual transmission? If so, flooring your car methodically while accelerating can improve mileage. I tried it and got 24 MPG city flooring my car. I'll explain it later on to leave you in disbelief for now.
I kind of doubt this, When I step on the gas hard, my ScanGauge shows me my mileage. It can be as low as .5 miles per Liter and when I speed up normally my gauge shows me about 3.5 Miles per Liter. Now I do have an auto, but I don't realy see why there would be a difference doing the same thing with a manual.
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Old 05-25-2008, 01:10 PM   #21
neko
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Full throttle/low rpm only works well for n/a engines as well. Like bulwnkl mentioned about fuel injection/ecu control, the amount of fuel you toss in in a turbo car when the throttle opens wide is huge compared to part throttle/off-boost. When you "lug" a turbo car, you'll load up on fuel and spool up the turbo to get the car going. not what you want.

Best way to add gas mileage on a turbo car like out WRX/STi's? Stick a wood block under the gas pedal... (figuratively) Drive it like a Vette, and you'll be lucky to break 20mpg. Drive it like a 100hp econobox, and it will act more like one at the pump. It may not be what you bought it for, but thats your call...

Easiest solution to me for getting better gas mileage, and also keeping wear and tear off your baby at the same time? buy a cheap little car that gets good mileage for you to-and-from-work driving and trips. Take your suby out on sundays (or in the winter). Before i sold my little 160hp mr2, even that un-aerodynamic house-brick would make 37mpg on the hwy. 27 around town all day running it like a bat outta hell. I'm lucky to get 27 in my STi, on the hwy.
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Old 05-25-2008, 01:44 PM   #22
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I'm talking about real world results I achieved with a five speed and piston cracking low RPM's. I do not plan on accelerating 0-35 in 13 seconds in the future. I did use sunoco 94 in an attempt to keep the engine from letting me kill it off.


I will go off topic now. I liked to experiment and do stupid things from time to time. My next experiment is to put 5w20 oil in my air cooled motorcycle and see what happens.
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Old 05-26-2008, 01:22 AM   #23
suub07
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Quote:
Originally Posted by wrxdrvr View Post
I have been putting in Acetone in my gas tank for 3 years experimenting how much works the best and came to the conclusion that 1 1/2 oz per tank works the best. Here are my mileage numbers for the last 6 years total average MPG per year;

'02; 21.8 MPG No additive in tank
'03; 22.1 MPG No additive in tank
'04; 21.4 MPG No additive in tank
'05; 22.5 MPG Experiment with 4oz Acetone per tank
'06; 22.8 MPG Experiment with 3oz Acetone per tank
'07; 23.8 MPG Experiment with 1 1/2oz Acetone per tank

http://www.pureenergysystems.com/new...00069_Acetone/
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Old 05-26-2008, 01:34 AM   #24
Ekeenan86
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Default Flooring the gas

With a manual transmission, are you implying you will receive better mpg by flooring it between gears? This makes sense because you are constantly keeping your rpms up, let me know if I'm wrong here, but letting the rpm's fall between gears kills you mpg more so than goosing it (love that term) to keep the rpm's up?
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Old 05-26-2008, 01:35 AM   #25
Ekeenan86
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Also, has anyone here found a good set of spark plugs that have yielded them improved mpg? I'm looking for a new set of NGK's and wondering if platinum would yield any improvements here.
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