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2000 Subaru Outback Limited, Manual Transmission
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Discussion Starter #1
Time to do some changes I think....

The car has a new air filter, plugs, wires, grounding kit, voltage stabilizer kit. 162,000 miles and a manual transmission. I was expecting more around 25. I drive pretty conservatively as well. I even take it out of gear when going down hill.

I would like to eliminate all these resonators in the intake piping. I'll keep the stock airbox and scoop, I just want to replace all that extra junk for a little easier breathing. I assume all 3 of those chambers are for sound.

Is burning oil common as well? I haven't seen the level go down, I can just smell it.


Also, what the heck is this little clip thing that's in the cup holder next to the e-brake!? I just discovered it today and can't figure what it is.
 

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Meh.
I has wagons.
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12,323 Posts
If that is all city driving, that's about normal.

Check the passenger front CV boot, if it is leaking it'll hit the exhaust and smell awesome[b/].
 

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DIY-Turbo 2.2l OBS 12.89s 1/4mile @ 106.17MPH
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399 Posts
Smelling oil burn can be a sign of leaky headgaskets.

Check the head to block area under the car for signs of oil leakage - if you see oil the HGs are/have been leaking - clean & re-check for oil in a month or so of normal driving if you see oil.

I averaged 31+mpgs with my 280lb buddy riding shotgun & 5 Iron bodied W50 transmissions loaded in the back of my 2003 Legacy L-SE wagon on a 440+ mile roundtrip through 4 states (NY, CT, MA, NH).

Not sure why OB guys get such bad mileage - I'm gussing it may have something to do with the lifted stance & heavy tires (transmission's short final drive should even out with the big tires on a OB vs small tires & LONG final drive on a normal legacy)
 

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DIY-Turbo 2.2l OBS 12.89s 1/4mile @ 106.17MPH
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Engine at idle runs richer than you think.
Interesting observation is my 1999 Impreza OBS gets the best mileage coasting in gear, while my old '00 Legacy Brighton Wagon & my current '03 Legacy L- SE Wagon both get the best mileage when coasting in neutral as observed while monitering instant MPGs on my Scangauge...
 

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2000 Outback 5MT
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425 Posts
If that is all city driving, that's about normal.

Check the passenger front CV boot, if it is leaking it'll hit the exhaust and smell awesome[b/].


I. Love. That. Smell. :headshake:


Also, what the heck is this little clip thing that's in the cup holder next to the e-brake!? I just discovered it today and can't figure what it is.
It pops out to help put pressure on cups that are small. Basically just keeps the cup snug in there. The pop out cup holder has one too.
 

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06 Outback 2.5i, 06 BMW 325xi wagon, 02 2.5rs, 82 CB750, Polaris XC SP 500, and a single speed bike.
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876 Posts
One thing to keep in mind on the manual transmission - when coasting in gear, the ECU cuts the fuel injectors. You get better mileage leaving the car in gear when coasting as you're not using any gas. The rotation of the wheels, through the trans, in gear, turns the engine. That's where compression braking comes from -- the compression in the cylinders pushing back against the rotational force of the wheels turning.

Have you replaced wires? Fuel filter? o2 sensors? Just throwing out ideas.

Burning oil, in my case, was the driver's side head gasket leaking and dripping oil onto the exhaust. Could only smell it at a stop.
 

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I even take it out of gear when going down hill. QUOTE]

Despite logical thinking, you actually will get better mileage by leaving your car in gear while going down a hill. The reason is that when you go down a hill while in gear, the cars momentum is carrying it forward and the engine is holding it back (some, depending what gear you're in). While the engine is holding it back, the computer is not dumping hardly any fuel into the cylinders since there is no need to. Now, while coasting down a hill in neutral, your engine will be at idle which the computer is dumping fuel into the cylinders as it normally would, thus using more fuel. I know it's hard to wrap your mind around this, it took me awhile, but if you had a digital MPG display in your car, you would see the MPG skyrocket when going down a hill in gear, and there'd be little change to mpg when doing the same in neutral.

oops, CSFiend you beat me too it!
 

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When my 2001 2.5 hit 150-160K I started to see a decline in mileage. I spoke with a couple of other friends with the same engine and nearly as many or more miles and they all said that they saw the same thing. Around town lots of idling - stop lights etc your mileage will drop the OB back then was called the fuel efficient alternative to the Ford Explorer which posted 16-18mpg. Subaru was never viewed as a fuel efficiency leader. The first ever claim along those lines was just recently when the new Impreza with the CVT and new engine design hit the market.

21mpg in mixed driving and cold temps with your car is pretty normal. I wouldn't go crazy spending money replacing stuff.
 

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2014 Legacy 2.5i 6M
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That's about what I get in mixed driving with my car. Pretty much the same configuration with a lot of city driving and 176K.
 

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2000 Subaru Outback Limited, Manual Transmission
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Discussion Starter #13
One thing to keep in mind on the manual transmission - when coasting in gear, the ECU cuts the fuel injectors. You get better mileage leaving the car in gear when coasting as you're not using any gas. The rotation of the wheels, through the trans, in gear, turns the engine. That's where compression braking comes from -- the compression in the cylinders pushing back against the rotational force of the wheels turning.

Have you replaced wires? Fuel filter? o2 sensors? Just throwing out ideas.

Burning oil, in my case, was the driver's side head gasket leaking and dripping oil onto the exhaust. Could only smell it at a stop.
I'm not sure I fully understand this. The RPM's are lower when it is out of gear.

I replaced wires. I plan to do the fuel filter soon because I have no idea when it was last done. Wouldn't bad o2 sensors give me a CEL?
 

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2004 Outback Wagon, 2.5, 4EAT, All weather package.
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Yes but the fuel to air ratio is much richer at idle than it is while running. You are using more fuel sitting there and idling than you would be at a given higher RPM.
 

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I'm not sure I fully understand this. The RPM's are lower when it is out of gear.

I replaced wires. I plan to do the fuel filter soon because I have no idea when it was last done. Wouldn't bad o2 sensors give me a CEL?
Fuel cut feature wasn't used till Gen4 2010 in the Subarus. So you can ignore this.

11yrs 180K on my 2001 5spd MT. I drove it several months shifting it and keeping the RPM's as low as possible my mileage was worse than it was driving it normally shifting in the 2000rpm range. 180K I got 25mpg on road trips at 70mph and under and semi rural areas the average was 23mpg. In San Francisco I ran 20-21mpg.

Road trips where I ran 70-80mph or had head winds mileage dropped into the 23mpg range easily. All time best ever mileage was at about 40,000 miles just me with a duffel bag and 400 miles of tail wind at 68mph. 28mpg for the tank one direction. The new Gen4 2010 we have at 40,000 miles same trip returned 32mpg both directions.
 

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06 Outback 2.5i, 06 BMW 325xi wagon, 02 2.5rs, 82 CB750, Polaris XC SP 500, and a single speed bike.
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Fuel cut feature wasn't used till Gen4 2010 in the Subarus. So you can ignore this.
Politely disagree with you. I'm pretty certain that it even mentions it in the owner's manual, but I biked to work today and can't check that...
 

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Politely disagree with you. I'm pretty certain that it even mentions it in the owner's manual, but I biked to work today and can't check that...
Be my guest. Even the 09 did not offer this technology. I had the same car you have trust me no such thing existed in the Subaru line up unless you physically shut the car off your self while coasting down a hill.
 

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2014 Legacy 2.5i 6M
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It should still cut the amount of fuel going into the cylinder when engine braking, moreso than just coasting in neutral. Even my 85 Firebird did that and it even mentioned in the OM that you should never coast in neutral purely to save gas.

Here is a link I found from Popular Mechanics.

Coasting in Neutral or Gear to Save Gas - Coasting and Fuel Economy - Popular Mechanics
Yes correct however thats not to be confused with the fuel cut feature newer cars have where the engine free wheels via the transmission with no fuel being used. This only happens under certain conditions meaning speeds higher than X etc.

To top it off this OP has a Manual Transmission so not only does his older car not have this new fuel cut feature - if he puts the car in neutral the engine reverts back to the very inefficient idle which is one of the most inefficient fuel burn points that the engine has. Ever been stuck in a major jam for a few hours idling? I burned nearly a half tank of gas in my 2001 in just shy of two hours idling with the AC on. Had no choice old dog was having a hard time with the heat and I was clearly not going anywhere anytime soon. The reason hybrids shut off when they are not moving or under a certain speed is because that is the highest fuel waste point in the gas engine range of use.
 

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06 Outback 2.5i, 06 BMW 325xi wagon, 02 2.5rs, 82 CB750, Polaris XC SP 500, and a single speed bike.
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Be my guest. Even the 09 did not offer this technology. I had the same car you have trust me no such thing existed in the Subaru line up unless you physically shut the car off your self while coasting down a hill.
Okay, so it doesn't completely shut off the injectors. However, it does use less fuel when coasting in gear than in neutral. Is that a point we can all agree on? The link that DarkPhoenix posted talks about this point -- the injector pulse width drops to near zero when coasting in gear.
 
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