Is it possible to disable (unplug rear differential?) the AWD option on a 2003 Outback without messing up with the system and put it back winter only? Would this improve MPG?
Yes, it is possible if you have a 4-cylinder model.
It is not possible on the 6-cylinder models because they have a different AWD system.
The process of disabling the AWD involves inserting a fuse into a special fuse receptacle placed (IIRC) just to the rear of the strut mount on the passenger side of the car. If you want details (including a graphic and the fuse specification), you should look in your Owner’s Manual, as this topic is covered in the manual. Have you taken the time to look at the manual?
As to whether it will improve your fuel mileage, it might make a very slight improvement.
Will this mess up the system? That I cannot answer.
Thank you VDCdriver. It is a 4cyl 2.5L. I’ll double check the manual as you mention. The idea behind disable the AWD was mainly to improve MPG, but I guess the car would still carry the same weight of all the components, so, you a re right, probably would not improve much… Let me ask you then, what would be the benefit of doing so, less tire wear? or no benefits at all? I am getting about 20.5 MPG, I believe it should go up to at least 22. I drive very softly, city and HWY (HWY 60MPH) Tune up was recently done, any idea in how to mimporve the gas millage?
The only ways to get better gas mileage are thus:
Remove any weight in the car you don’t need.
You can even remove the jack and the spare tire and jack if you feel like taking a risk, and/or having a good roadside assistance program.
Only idle the car for 30 seconds after starting it before you start driving.
You don’t need to let the car idle for several minutes to warm it up before driving.
Just start and go.
Use the thinnest engine oil Subaru recommends.
If you’re using 15W-40 when the car only needs 5W-30, you are wasting gas every mile that you drive.
Keep the rpms low.
If you can safely drive in traffic without accelerating past 2500, or even 2000 rpms, you will save more fuel (this is how I have been averaging 31 mpg in my Nissan Altima over the past year, instead of the typical 24 mpg that I was previously getting).
If your car has wide performance tires on it, if you can switch to the base model wheels and tires, that are a thinner width, you can save a bit of gas that way.
There are others also, but these are the easy ones.
thank you Bladecutter, good hints. My driving part is as you recommended. I’ll remove the jack and spare and test it that way with for a full tank. The tires are almost new (got the car with those) and will change them later on, maybe I’ll get a set for summertime and the one I already have on for the winter.
About the oil, I am using synthetic oil(for the first time) since the car has 150K already and my mechanic recommended it.What do you think? Should I go back to normal 5w-30 oil or semi-synthetic?
I got the Outback a month ago, the previous owner told me he was getting 19 MPG. I have done a full tune up and went up to 20.5, but I was sure I would be able to get 23 or 24! I’m losing the bet by now.
I doubt there would be any change at all. From what I understand from my ownership of a Subaru, the center differential varies the amount of torque between front and rear. Whether it’s 100% front if the fuse is disengaged or 50% each way as needed for example is of little consequence; your mileage won’t change. It doesn’t change in use when on a straight level road, as much as 90% front to 10% rear may be the norm. If it did significantly improve mileage, don’t you think they would give you a lock out feature, like truck based and the very early Subarus had ?
Besides, in all of my 3 awd cars, tire mileage was significantly better than fwd alone. What you may “think” you save on one end, you definitely loose on another.
Rather than dither about gas mileage and the possible impact of disabling the AWD of this car, I would suggest that you focus instead on possible lapses in maintenance by the previous owner. Prime on my list would be the timing belt.
Since your car is now at least 7 years old, if the timing belt has not been replaced, it is due very soon on the basis of elapsed time. It is supposed to be replaced at 105k miles or 8 years, whichever comes first.
When that belt snaps (not if it snaps), the engine will incur very heavy damage to valves and pistons. Assume about $1,500 over and above the cost of the timing belt for repair of this engine damage.
When you replace the timing belt, you should also replace the water pump, serpentine belt, and all belt tensioners.
Also, I hope that you were kidding about removing the jack and spare tire in order to reduce weight and (possibly) gain a tiny fraction of a gallon in fuel economy. Even fairly new tires can get a puncture, and driving around without a spare and a jack is…not wise. This would be a good illustration of being “penny wise and dollar foolish”.
One way to disable it would be to remove the actual AWD components such as the center differential, drive shaft, and any other parts associated with it, then pop in that FWD-only fuse. The weight saved by removing those parts should increase fuel economy a little bit. Though you will have to put the parts back in once winter hits, and if you aren’t mechanically inclined, the money you save in fuel will be lost 10 fold by paying a mechanic to install/remove these parts. In other words, you’re better off not worrying about this.
Also, I question why you’d buy an AWD vehicle then worry about fuel economy when an FWD vehicle will yield better fuel economy than AWD
The automatic and the stick have different AWD systems. Either way, the wheels will be turning most, if not all, of the disabled components anyway, so you’ll still have the mechanical drag. Remember also that, at around 3,400+ lbs., this is a fairly heavy car, and it is going to take some fuel to move it around. I think ditching the spare tire and the jack is kind of like taking a gallon of water out of Lake Erie. Not worth getting stranded over. 20-21 MPG isn’t bad for a car this size in the city. Highway you should get 27-28 or better.
removing the jack and spare tire ??? how much weight are you really saving? remember to drop off all your passengers and remove the rear seat, they weigh more than the jack and spare.