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Trans(2 drain plugs) and Rear Diff Fluid Change

41K views 42 replies 30 participants last post by  JZeezSTi  
#1 · (Edited by Moderator)
ADMIN EDIT: Scroll down to see official Subaru documents and the IWS discussion pertaining to the two drain plugs.



Got the fluids to do my own transmission and rear diff change.

Just wondered if there was any additional parts I would need from the dealer like crush washers such as the engine drain plug has?

Also, are there 2 drain plugs for the tranny? A quick look underside and I saw one drain plug. Where is the second one?

Thanks...
 
#3 ·
bikerboy said:
No aditional parts needed.

Two plugs: one on the little pan on the bottom of the tranny. The other is twards the front o fthe car on the center diff housing. When your under there you cant miss it.


BB
awww darn.... i only saw one plug when i did mine.. think i should drain it again?
 
#5 ·
mcR - I would just make sure you didn't overfill it, however you may have just gotten a mix of dino and synthetic oil (if you put synthetic in), since it may not have all drained out ... heres a pic.

Image


Robert~
 
#8 ·
staticx313 said:
mcR - I would just make sure you didn't overfill it, however you may have just gotten a mix of dino and synthetic oil (if you put synthetic in), since it may not have all drained out ... heres a pic.

Image


Robert~
i didn't use synthetic.. i thought i was bad for our cars
 
#10 ·
You have to drain both to do it properly.

If you just drained one and got the same amount of oil out as draining both then you must have drained the lowest one, but I still don't see how that is possible.

Think about it as draining the oil and particulates out of the motor side and the center diff (clutch) side. You want to get the old oil and the microscopic contaminates fully out of the system right? Otherwise you'd never need to change oil. If you just drain one your just gonna mix old metallic particulates from either the engine, or the organic crap from the clutch into your new oil. So your robbing peter to pay paul in a sense. In other words do both or don't waste your time. Its kinda like changing oil without changing the oil filter. A complete waste of time.
 
#14 ·
How often would i have to do this, if i even have to do it at all? I thought in manual transmissions, you didnt have to change the oil, or something like that. I never changed any trans oil in my VW. I dont know much about trannys, so sorry in advance if this is a dumb question.
 
#15 ·
Can anyone post the same type of instructions for the rear diff fluid change. How doy you take the temp sensor off to get the full plug out without breaking the sensor? Is the stock fluid Valvoline Gear Oil 75W-90 dino? I was thinking of getting the Valvoline High Performance Gear Oil and sticking with the dino oil so it doesn't mess with the limited slip like some people are having problems with. Thanks for any help you can give.
 
#16 ·
Re: RE: Re: RE: Re: RE: Dual Engine Management = Best EM for

From what I can remember, I just sort of carefully pulled on the sensor/plug to un-plug it and then unscrewed the nut it was plugged into. I have seen a number of posts on here and other forums that most dealers use Valvoline gear oil so that is what I used in my diff and trans. Not sure if Valvoline comes from the factory in Japan in the diff though. BTW, the diff seems fine and the trans still shifts like butter regardless of temps outside.
 
#17 ·
TL-racer/STi-driver said:
Can anyone post the same type of instructions for the rear diff fluid change. How doy you take the temp sensor off to get the full plug out without breaking the sensor? Is the stock fluid Valvoline Gear Oil 75W-90 dino? I was thinking of getting the Valvoline High Performance Gear Oil and sticking with the dino oil so it doesn't mess with the limited slip like some people are having problems with. Thanks for any help you can give.
Just simply unplug the sensor, and unscrew the BIG bolt... the sensor can unscrew out of the big bolt, but do not do this. We did this to fill it and overfilled it somewhat and had to remove the big bolt in the end (allowing another .1L to drain out or so). I would ask the dealership what oil comes with the subaru, but i am sure its the valvoline and i think its 75w90.

Robert~
 
#22 ·
#23 ·
tealturbotwo said:
robert- does your manual have the page for the rear diff? I am still trying to get a straight answer on the type of fluid. the dealer claims it's regular 75w90, but i heard on here that it's different.

any ideas?
Dan
I just researched and did the rear diff fluid change. It uses different oil than the trans/front diff. The rear requires LSD oil. The Subaru stuff is KO305Y0900 LSD 1 Liter and costs around $20. You will also need part number 004403010 FUJI BOND C liquid gasket which comes in a tube of way more than you'll ever need for $12.

There are a couple of alternatives to the Subaru LSD oil, but they MUST be LSD oil. I don't know what they are, but if you search it's easy enough to find.

P.S. Some type of pump (a.k.a. fluid extractor) to get the fluid out of the can and into the diff makes the job much easier. $6 at Advance.
 
#25 ·
I just did the rear diff fluid change and it was very funny actually. Here some lessons I learned.

1. Don't drain the diff unless you have figured out a way to put fluid back into it. I didn't bring my fluid pump and though that I could use a small funnel. Nope. I ended up putting together 4 extensions from Auto Zone together to create a big enough pressure differential for the fluid to go into the diff.

2. Once you get in contact with the fluid it will stay there forever. My car still smells like it after a week. That stuff will get to you so if you like to wipe your hands on your shop pants or so think twice before you do it.

3. If I was to do this again, I would tilt the car slightly upwards, meaning front higher than rear. The fluid is really thick when its dirty hence not all of it comes out with just the drain plug loose.

Anyhow, it is a really quick job and for the drain plug you can use the 1/2 inch head on your torque wrench or breaker bar. It works fine and doesn't strip the drain plug. For the filler plug make sure you disconect the sensor and than use a 30mm socket. Don't use a wrench cause you might strip the plug.
 
#26 ·
Oh, I almost forgot. I bought the subaru LSD fluid and when I opened up the can the smell was so familiar that I sat down for 10 minutes trying to remeber what it is. It smells exactly like dextron III ATF fluid because i worked with quiet a bit when I revalved dampers. It is not red like the dextron but I think the stuff is almost the same.