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Pictoral Guide to Changing Transmission and Rear Diff Fluids- 5MT 05+ Legacy GT

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This post will be the full guide for all of you out there with 5MT 05+ Legacy GT/Outback XTs.


The job itself is pretty simple, and should take you about an hour if you are not rushing.


I would give this a difficulty of 1.5 stars out of 5, only because of finding all the supplies.


Tools and Supplies:


1 T70 Torx Bit (eBayed mine)

1 1/2" Ratchet

2 short 1/2" extensions for the ratchet

Screwdriver for the pop-its on the engine cover

Drain Pan

Jackstands and ramps to get the car at level when up in the air

Fluid Pump for the rear end

Funnel and 3/8" inner diameter clear vinyl tubing

Lots of paper towels




I used:

4 QT Redline 75W90NS for the Front Transmission

1 QT Redline 75W90 Gear Oil for the Rear End


But other options exist





Thanks to PSUcaptiankickass for these next numbers:


Oil Drain Plug: 33 ft-lb

Transmission Drain Plug (T70): 50.6 ft-lb

Now the Rear Diff is different depending on what car you have. (This info comes from the 2005 service manual as well, keep in mind)

Legacy 2.5 L Non-Turbo

MT has the T-type Diff: 36.2 ft-lb (both Drain and Filler Plugs)

AT has the VA1-type Diff: 25.3 ft-lb (both Drain and Filler Plugs)

Legacy 2.5 L Turbo

MT has the T-type Diff: 36.2 ft-lb (both Drain and Filler Plugs)

AT has the VA2-type Diff: 21.4 ft-lb (both Drain and Filler Plugs)


Outback 2.5 L Non-Turbo, and MT 2.5 L Turbo

has the T-type Diff: 36.2 ft-lb (both Drain and Filler Plugs)

AT 2.5 L Turbo

has the VA2-type Diff: 21.4 ft-lb (both Drain and Filler Plugs)


And capacities:


4AT = 1.2 - 1.4 qt

5AT = 1.4 - 1.6 qt

5MT = 3.7 qt


0.8 qt all models.



Step 1


Turn on the stereo and put on your hat and gloves




Good, This is where I jacked up the car on the front end, the rear I just use the differential itself:



Car in the air:


This car has room for my Dubs I ordered right? :spin:


Get under the front to undo the drain plug, here is where you need the T70 Torx Bit





Its on there tight, but you should be able to get it. Have the pan ready, it does tend to gush towards the passenger side of the car:



Let it drain for awhile, in the mean time clean up the plug, it is magnetic so it should have fine particles on it. This is normal.



All Cleaned Up:




So clean and fast is is blurry.


Reinsert the drain plug, there is a copper crush washer here you can replace. I did not do that with no ill effects so far, but it is your car, and Subaru does say to replace it.



All clean and re-installed


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Up Top under the engine bay now.


Remove the engine cover, this means pop-its, I already had my cover off from another project, so sorry no pics of this, there are four pop-its and they love to break off, so be careful. You need a standard phillips screwdriver I believe.


Now look on the passanger side of the engine bay, just where the turbo is mounted.




I have no heatshield after going stage 2, so it may be a bit more hidden for you.


A bit further out:



Now is when you get the funnel and tubing: remove the metal dipstick, and the tubing will actually slide into the fill tube.






Fill with 4 QTs of fluid, the NS version:





Tidy everything up front, you are done. Don't forget to put back in the dipstick.

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On to the rear diff.


Look under the car, you will see on the rear diff there are two plugs. Looking at the plugs, what size is that? Just having a 1/2 Ratchet works fine, not an exact fit but good enough. The bottom one just use the ratchet by itself, the top one we will need extensions.


Edited: top plug can be done first if you are worried about the plugs being 'frozen' this way you can still have fluid in the diff.




And here is why you cannot do this from straight on, hello exhaust!



OK, now for the bottom one:




This stuff really stinks, so beware:






Here is how I got the top one out:




And comparing the two plugs, Magnet on the bottom FTW!




Ready for fluids good sir!




And this is where the pump comes in handy. I usually pump a bit of fluid into the diff with both plugs out, it can only hold about .7 QT anyway and it can help get out the last of the old fluid.


Then when ready go ahead and re-install the bottom plug and put the pump into the top.




Filling the Diff:




And achieving overflow.




Finally button everything up-




And congratulate yourself, you just save hundreds on your next service by doing the work yourself.


Oh, and be glad that you are not in Arizona in the summer, this is in my garage, in the morning:



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You can do that, but looking at other threads on the forum there is an additive in the NS that is supposed to be designed for the manual transmission. I know that for the past 30K things have been great in my car, so I just went with what I knew. I contemplated royal purple, but did not do enough research before I needed to get the change done.
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Grist for the mill ... I have a buddy who is a certified mechanic,

with lots of experience on Subaru's, and he claims several things

that may be controversial here.


First, that he's talked to Subaru tech folks and they say the factory

fill is regular Valvoline 75W90. Second, he's tried many other

products, including the Redline touted here, and none shift as well

as the Valvoline. Third, I asked about my tranny oil looking really

clean, so why should I change it. Fourth, he says Sube tranny is

pretty wimpy so to "baby" it. See below. FWIW. YMMV. ETC ...


> > No. I change tranny and diff oil, esp tranny. Tranny and diff

> > oil always looks clean, in everything. What wears out are the EP

> > (extreme pressure) additives in gear lubes. Plus, they get

> > micrscopic metal shavings suspended in it (tiny parts of your

> > gears, yikes.) You are used to seeing combustion byproducts in

> > motor oil, none of that in gear lubes. Subaru tranny was

> > designed 35+ years ago, they are a small volume maker with

> > limited R&D budget, they took a long time to design a new

> > tranny, that is the 6 speed, and it's not in everything yet. The

> > 6 speed is a great box, beefy, pressure lubed. The 5 speeds is

> > the 35 yo box periodically beefed up (with moderate success) to

> > meet increased powr and weight rwequirements. 1970 Subaru

> > weighed prolly 2000 lbs, had 90 bhp, ones now with 5 speed prolly

> > weigh 3500 (if not more) and have as much as 250 bhp. Much like

> > pre 1994 Saab 900s in that respect (another car famous for having

> > a "glass tranny".) I beleive in babying that

> > gearbox. Valvoline 75/90 is factory fill, I have tried all kinds

> > of magic elixirs, none shift as well as the Valvoline. The ones

> > with better friction coefficients make the synchros (which require

> > a certain amount of friction to do their thing) all confused. I

> > believe in changing it a lot b/c it's probably not the "best" oil

> > out there.

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On to the rear diff.


Look under the car, you will see on the rear diff there are two plugs. You will want to do the bottom one first for the fluid to drain properly.......


The smart thing to do is to remove the top plug first. Because if you remove the bottom plug first, and the top plug is frozen, you are SOL.


And the bottom plug does not need to be removed first for the fluid to "drain properly".

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Not a bad idea, I am not in an area that sees any sort of snow/ice ect so have never dealt with frozen bolts.


As for the use of redline, I guess it is your perrogative, I am happy with is in my other cars, so used it in this one as well. When I did the first change it did feel better with the redline and engages 3rd and reverse much easier for me.


The guide was not supposed to be an opinion of the fluids used, more of a "where the heck is the drain located" post

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I did mine at 30k on a 5MT.


Regarding the NS versus Non-NS redline fluid:


Exactly, which is why my post #105 in this thread quotes Redline's site:

Regarding 75W-90

"Our most popular gear oil, this is the preferred product in nearly all car and light truck differentials, both conventional and limited-slip. 75W90 is preferred for most racing applications. It contains friction modifier which is recommended for limited-slip units. 75W90 Gear Oil can be used in many transmissions and transaxles; however, other Red Line lubricants have better frictional properties for rapid synchronization. Exceeds API GL-5."



"This GL-5-type gear oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin."


Based on this information, I used 75W-90NS (no friction modifiers) in the transmission and rear diff, since the VC type diffs do not rely on the gear oil to achieve limited-slip properties.

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To the whole valvoline vs. redline thing:

Factory fill feels like molassas in the winter time.

The redline is much smoother at startup in the cold.

At any other temperature, I probably would rock the valvoline. Just for the cold though, I use Redline.


Interesting. NC is a fairly warm climate, as is NM where friend

(who loves Valvoline) lives. Maybe for those who live in northeast

or Rocky Mtns the choice is different.

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