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Discussion Starter #1
Has anyone else noticed this same thing? Have a 2008 Outback 2.5 and I have recently noticed that my gas mileage has not been the same. Over the last month and a half I seem to only be getting an average of 135 mpg from a full tank to half a tank. I've been using the trip/fuel/outside temp gage as a reference which now will read anywhere from 22.4 mpg to 19.8 mpg. A great majority of my driving is freeway driving, prior to this it would normally read 26.8 to 27.4 mpg. Could this big difference be due to we are now using Winter Grade fuel or is the above gage not a true source to use? When I was or thought I was getting better mileage, I could go approximately 300 miles from a full tank to a half tank, not anymore:( I have even taken the car to the dealer for their thoughts and they say it is normal mpg's and even had them do a 90,000 maintenance service on it.
 

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I have noticed it since about mid-late October in Montana. I am getting about 26 highway and 20 in town now vs. 30/23ish
From your reply it looks as though it may be the Winter grade fuel though I'll keep monitoring my mpg's up through the time it's time for the summer grade fuel. By the way, you may know the answer to this other question if you yourself use snow chains, are they placed in the rear or up front?
 

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2011 Tacoma TRD Sport Double Cab Long Box
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I dropped about 2 MPG from my usual sometime in November and other than a tank or two that had a lot more highway driving, it hasn't really gone up. I assumed it was winter fuel then.
 

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^What he said.

Its the antigel and oxygenated additives in the fuels. It doesn't burn well and your car adjust to get the same stoichiometric equation and power output by adding to the injector timing/latency. Run with higher octane gasoline. Its better for the car anyway.
 

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2013 Outback 3.6L Limited with EyeSight
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Run with higher octane gasoline. Its better for the car anyway.
I agree with cardoc; well said!

My 2013 6-cylinder Outback is 7 weeks old with 3,900 miles and has been averaging 23.8 on the MPG Display (22.8 actual) with a lot of short trips (50% city / 50% highway).

Have recently upgraded engine, trans, and differential fluids to Group IV & V synthetic fluids and run 38 psi in front tires and 35 psi in the rear with 87 Octane Mid-grade fuel from Chevron. Average temperatures range from 30*F to 15*F.


Merry Christmas! :D
 

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2011 Tacoma TRD Sport Double Cab Long Box
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^What he said.

Its the antigel and oxygenated additives in the fuels. It doesn't burn well and your car adjust to get the same stoichiometric equation and power output by adding to the injector timing/latency. Run with higher octane gasoline. Its better for the car anyway.
I always run 93 in my H6 (recommends 91 or better anyway)...maybe that's why I didn't see as big a drop as some.

I agree with cardoc; well said!

My 2013 6-cylinder Outback is 7 weeks old with 3,900 miles and has been averaging 23.8 on the MPG Display (22.8 actual) with a lot of short trips (50% city / 50% highway).

Have recently upgraded engine, trans, and differential fluids to Group IV & V synthetic fluids and run 38 psi in front tires and 35 psi in the rear with 87 Octane Mid-grade fuel from Chevron. Average temperatures range from 30*F to 15*F.


Merry Christmas! :D
87 Midgrade? You must live at a high elevation. 87 is "regular" here...never seen a station with anything lower.
 

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Before the Supercharger installation, I ran a test on the car to see how it would perform with regular, 87 octane vs premium, 93 octane. Higher octane fuel resulted in more power and higher mpg. Its reduced in carbon deposits in the combustion chamber and burns cleaner and more complete. Which means getting all the power available from the burn. The calculated load on the engine was lower. The detergent additives in higher grade fuels also keep the injectors and valves cleaner. With the top tier gas, longer interval between fuel filter replacement, throttle cleaning and intake services. In the long run, better running engine, more performance, and lowered maintenance cost.

I tell all my customers, Run what ever you like, its your car. I can only tell you from testing and experience what results I've seen. Temperature and altitude also make up a large portion of the fuel's ability. Winter = highest octane available.
 

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Before the Supercharger installation, I ran a test on the car to see how it would perform with regular, 87 octane vs premium, 93 octane. Higher octane fuel resulted in more power and higher mpg. Its reduced in carbon deposits in the combustion chamber and burns cleaner and more complete. Which means getting all the power available from the burn. The calculated load on the engine was lower. The detergent additives in higher grade fuels also keep the injectors and valves cleaner. With the top tier gas, longer interval between fuel filter replacement, throttle cleaning and intake services. In the long run, better running engine, more performance, and lowered maintenance cost.

I tell all my customers, Run what ever you like, its your car. I can only tell you from testing and experience what results I've seen. Temperature and altitude also make up a large portion of the fuel's ability. Winter = highest octane available.
Good info...thanks!

When I bought my '04, the previous owner had been running 87 octane in it and it had about half a tank. After the second fillup of 93, I could have sworn it had a bit more power. Hard to judge MPG because my drive back from buying it was all highway and my next couple tanks weren't. Haven't run less than 91 in it since (and I've only run 91 when I've been in upper Maine where there's no higher fuel available).

The fuel filter thing is definitely worth thinking about--in '04, they eliminated the filter under the hood, so it's not as easy to swap. Apparently the in-tank filter is a life-long part :rolleyes:.

If I buy the '09 3.0R I'm looking at, it will certainly get high octane fuel all the time anyway. It's amazing how shocked people are that I use 93 when it's only "recommended." On the rare occasions that I go to a full service station the attendant looks at me like I have two heads. The price difference isn't THAT huge. I can afford a few bucks a fillup.
 

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04 began a new era for California emissions standards. All CE vehicles have the filter in the tank.

When you calculate the cost and time to keep the engine's induction system clean, valves clean and fuel system clean, using the premium unleaded is about the same cost and in some cases cheaper. Enough carbon builds on the valves and performance suffers upto the point a valve job is needed due to heavy build up or valves not closing proper. Which can also cause oil consumption.

Preventative does not mean "if you want to". It's to prevent abnormal wear and keep the performance level where it is intended.

High octane is the way to go to keep cost down. And better running engines in colder climates.
 

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04 began a new era for California emissions standards. All CE vehicles have the filter in the tank.

When you calculate the cost and time to keep the engine's induction system clean, valves clean and fuel system clean, using the premium unleaded is about the same cost and in some cases cheaper. Enough carbon builds on the valves and performance suffers upto the point a valve job is needed due to heavy build up or valves not closing proper. Which can also cause oil consumption.

Preventative does not mean "if you want to". It's to prevent abnormal wear and keep the performance level where it is intended.

High octane is the way to go to keep cost down. And better running engines in colder climates.
I think all '04+ Outbacks come sans under-the-hood fuel filter, but mine is probably a Cali-spec car anyway since it was sold new by a MA dealer. Interestingly enough, I think mine even has the bracket to hold the filter, just no filter.
 

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2013 Outback 3.6L Limited with EyeSight
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Preventative does not mean "if you want to". It's to prevent abnormal wear and keep the performance level where it is intended.

High octane is the way to go to keep cost down. And better running engines in colder climates.
Great advice!

"Prevention is much better than redemption!"
 

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From your reply it looks as though it may be the Winter grade fuel though I'll keep monitoring my mpg's up through the time it's time for the summer grade fuel. By the way, you may know the answer to this other question if you yourself use snow chains, are they placed in the rear or up front?
I'm pretty sure they go on the front, but I would suggest reading the manual as I have never used chains on the subie. My tires are trash, if it's bad out I just try not to go anywhere ;)
 

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I keep insisting to my wife that she should use 93 octane whenever it is 30 cents or less more per gallon than regular piss. I keep telling her with more power, the car won't need to downshift as often on the long interstate hills and the car will get better gas mileage, be a bit more peppy and basically pay for itself, and then some.

Some people you just can't tell.
She thinks cheap is cheap. She doesn't want to hear the rest of it.
 

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2012 Outback 2.5 i Premium
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It's not that much more per tank to run premium. It's less than a fancy cup of coffee in most cases.
 

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Snow chains: older Subies, front. Newer, rear. I've never used chains on any of my Subarus. Even when I lived where it snowed heavy. They've always treked (lawsuit? :gasp: ) right through.
 
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