Author Topic: Rear-diff and Gearbox oil change  (Read 3326 times)

April 12, 2017, 10:41:16 PM
Read 3326 times


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For those attempting to do this DIY.
i did this a week ago, so I thought I would share.

It's an easy job, but you need some tricks and tools. The normal screwdriver and pliers and hammer are not sufficient.
A jack is meant to lift a car, not support it while you are underneath the car.

The description that follows is for the SG9 NA/ Pre facelift MT. I know the Facelift has a different exhaust routing. The turbos would also have a different routing, so the tin foil for the gearbox drain might not be required..............

Rear Diff:
This should be the same for all SG models. some might have a sensor connected to the bootom diff plug, which will need to be disconnected. I have no experience in this regard.
Jack, car stand, 1/2 drive power bar, extension pipe for power bar, if you have a short one (power bar  ;D ;D), some blocks of wood, or bricks, or sparewheel (don't use your head for the latter 3 items). And oil drain can/bucket.

Jack up the car at the rear, one side is ok, or under diff. Support with stand (bokkie/ ....), for safety sake.
Clean the areas around the plugs.

The power bar's 1/2" drive fits into the plugs on the diff.

Insert this into the top plug, support it with the wood/ bricks/sparewheel as shown in pic(shown for bottom plug).

Don't bother trying to undo the plugs by hand.
Lower the car, and let the weight of the car do the hard work of undoing the plug. You may hear something break, but that's just the plug coming loose.(hopefully nothing actually breaks)
I have used a Gedore power bar. Not sure if the "Fung-Yong-Hai" models will work. You know, those shiny "Chrome Vanadium" ones. They might be too weak.

Anyway, jack the car up again, repeat for the bottom plug.

Now you can procede with removing the plugs(top first), draining, and refilling the oil.
When re-fitting the plugs, add some "Loctite" thread sealer. Don't use PTFE tape, the oil will sweat through.
Obviously, insert the bottom plug first, fill via the top hole.

The reason for loosening the top plug first, is to ensure that you can actually refill the diff, once drained. No good you drain the oil, and then can't refill.
For those not having a manual, you refill untill the oil flows out of the filler(top) hole.

Gearbox (MT)

You'll need some additional tools: Torx T70 bit(borrow one somewhere, they do cost a few rand to buy), some tinfoil, a small funnel, 16mm tubing(Aquarium/Gardening, or even better, PVC or Perspex pipe), long enough to reach from the gearbox dipstick tube to above the airfilter/throttle body. (See pic)

Also make sure you have a new gasket for the drain plug. It's good practice to fit a new gasket. (The plug's thread OD = approx.25.5mm So, an Alu seal (like on sparkplugs), or a copper seal(washer), with ID 26 mm, should be OK. I actually got a new one from SSA (when I bought my new plug)).

The tin foil is needed to cover the exhaust pipe Y-piece (on the SG9 NA/ Pre facelift. Don't know about the others)
Form the tin foil so as to provide a path for the oil to run freely down into your oil drain pan. If you haven't got tin foil, you will probably suffer with the hot/burning oil smell for a week or so.

Jack up the car, and support on stand (again for safety).

Using the T70 bit, power bar and extension pipe, as well as all the anger over the neighbours screaming kids, and (if you have) the nagging missus, barking dog, pregnant GF, lossen the drain plug at the bottom of the gearbox, whilst pushing against a wheel with your foot/feet.....
Let the oil drain for an hour or so.

Refit the plug (+(new)gasket), tighten, and then a bit more.

Refill with 4lt of oil, thru the funnel contraption. Ensure hte level is fine.

After a week or so af driving, just make sure there are no leaks, check the gearbox oil level, and enjoy your car.

Before starting this job, make sure you have the oils. Duh. ::) ::)
You won't get them at Hypermarket/ Makro/ Checkers

Above all, work safe!!

No, you don't need to disconnect the battery, and loose all the radio presets..............

Subaru Forester 2005 2.5 Xsel
Always looking for a tar free "road"
Brackenfell, W'Cape

April 23, 2017, 07:32:26 PM
Reply #1


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Did you not struggle with the T70 plug? Gave up today, it would not budge and the "teeth" of the plug started getting damaged.  Also, I see you bought a new plug, did you get the same type or the FL hex type? Would like to kick the person who decided to use the Torx plug on the zip.
14 Subaru Forester XS Lineartronic
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04 Subaru Forester XSel

07 Subaru Forester XS
05 Subaru Forester XT

Richards Bay - KwaZulu Natal

May 17, 2017, 10:26:25 AM
Reply #2


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Edit 19/08/2018
Somehow the "pic" (for undoing the diff plugs) did not make it to this post before??

Here it is:


Hi Divan,
Somehow missed this reply.

I got the OEM plug from SSA. Didn't know the FL had a different plug.

I replaced mine because the teeth were stuffed, but good enough to get the plug out.

It does sit in a very stupid place. I think if you struggle too much, you can remove the exhaust, and then try removing it with a Bobbejaan spanner (Stilson).
Or, weld something to the plug head, to allow better grip (i.e. socket or something)
There are ways.
« Last Edit: August 19, 2018, 08:28:33 PM by berndp »
Subaru Forester 2005 2.5 Xsel
Always looking for a tar free "road"
Brackenfell, W'Cape