What you need for a rear differential fluid change

Singletrack · 11-06-2005, 03:51 PM

K0305Y0900 - LSD (75W-90 GLS), previously K0904AA080
004403010 - Three Bond 1105 (liquid gasket)
Large adjustable wrench or corresponding socket (not sure on size)
1/2" breaker bar
Hand Pump
Fluid Extractor (optional)
Torque spec on plugs: 49.0 N·m (5.0 kgf-m, 36.2 ft-lb)

I drove the car up on ramps in the front, jacked the rear diff until the car was about level, and put the back on stands under the side jack points. Clean off the area around the plugs to keep any debris out of the diff; it will also make it easier to find any leaks. I pulled the top plug first (pull the sensor harness first) to make sure it wouldn't give me any trouble. Use a large spanner, adjustable wrench, or properly sized socket (I didn't measure). Some oil poured out (probably wasn't a 100% level), but not much. Put the plug back in so the oil wouldn't run into the bottom plug. I pulled the bottom plug (1/2 drive breaker bar) and drained the fluid.

The fluid was BLACK (30k miles) and there was a fair amount of metal on the magnetic drain plug. I pulled a tiny bit more oil out of the bottom with the fluid extractor - not much though really. Replaced the bottom plug (with liquid gasket on the threads), pulled the top, and put the pump tube in. I got a pretty decent one that has some teeth to hold onto the threads in the diff. Pump like a madman. Mine took about .9liters before it started running out of the diff. Replaced the top plug (with liquid gasket).

NOTE: At least 2 people have broken their top plug with the sensor. I am not sure what the cause of these failures actually was, but make sure you do not over-apply the liquid gasket and then over torque the top plug. The gasket acts as a lubricant and WILL affect the torque wrench to some extent. Covering the threads from the halfway point to the head of the bolt is probably sufficient.

STi05' · 11-06-2005, 11:39 PM

Do you think it would be worth while to say run on that oil for a 100 miles or so, then change it again? That might make sure you flush out all the old oil and filings. Just a thought.

**jsh139** · 11-07-2005, 06:27 AM

Good call on loosening the filler plug first

Imagine draining out all the diff oil and then not being able to fill it because the filler plug is seized!

Singletrack · 11-07-2005, 08:02 AM

Quote:

Originally Posted by STi05'

Do you think it would be worth while to say run on that oil for a 100 miles or so, then change it again? That might make sure you flush out all the old oil and filings. Just a thought.

Yah it might, but at $19 a liter I'm not jumping to do it : )

MeoW71 · 11-19-2005, 11:41 AM

Quote:

Originally Posted by Singletrack

004403010 - Three Bond 1105 (liquid gasket)

Just wondering what else I could use instead of this. Something I could pick up at any autoparts store.

Singletrack · 11-19-2005, 12:23 PM

Quote:

Originally Posted by MeoW71

Just wondering what else I could use instead of this. Something I could pick up at any autoparts store.

Do a google for "three bond" and "substitute" and you should find some. Certain manufacturers list substitutes for competing products.

qingshan · 01-11-2006, 02:57 PM

Quote:

Originally Posted by jsh139

Good call on loosening the filler plug first

Imagine draining out all the diff oil and then not being able to fill it because the filler plug is seized!

Had that happen once

Very good to pull the fill first

qingshan · 01-11-2006, 04:23 PM

[quote=Singletrack]K0305Y0900 - LSD (75W-90 GLS), previously K0904AA080
004403010 - Three Bond 1105 (liquid gasket)
Large adjustable wrench or corresponding socket (not sure on size)
1/2" breaker bar
Hand Pump
Fluid Extractor (optional)
Torque spec on plugs: 49.0 N·m (5.0 kgf-m, 36.2 ft-lb)

I I pulled the top plug first (pull the sensor harness first) to make sure it wouldn't give me any trouble.

How does that sensor get pulled

qingshan · 01-11-2006, 07:20 PM

Thanks - I got it done Mobile Syn in the diff, trans lube next with my Kartbot ss install

solbergfan · 01-13-2006, 06:16 AM

Quote:

Originally Posted by qingshan

Thanks - I got it done Mobile Syn in the diff, trans lube next with my Kartbot ss install

The rear diff requires a 90 wt. LSD oil, which Mobil does not make, so it sounds like you put the wrong stuff in. You need to use Subaru 90 wt. LSD oil or Motul 90PA LSD oil which is an equivalent.

Horatio · 02-22-2006, 09:32 PM

Nice post Singletrack

I just got done reading this and the trans thread and wanted to say thanks for the heads-up on the gasketsfor the trans, along with pointing out the appropriate liguid gasket. I did some checking and was a bit surprised that the Three Bond Subaru recommends for the rear diff is not the same as Permatex ultra grey. Glad you brought it up otherwise I am certain I would have used the wrong stuff without having any clue.

I know there will be people saying no big deal, and they may be right, but why risk it when Subaru specifically endorses Permatex ultra grey as an appropriate substitute for a host of other applications, just not for the rear diff.

Thanks again. (no, I am not posting appreciation in both threads)

dareseven · 03-25-2006, 11:16 AM

Excellent write up. Much appreciated.

**abdi** · 03-25-2006, 06:06 PM

Quote:

Originally Posted by solbergfan

The rear diff requires a 90 wt. LSD oil, which Mobil does not make, so it sounds like you put the wrong stuff in. You need to use Subaru 90 wt. LSD oil or Motul 90PA LSD oil which is an equivalent.

Just to kind of piggy-back what you said. You can use Silkolene BOA90 LS as well. I like both Motul and Silkolene.

Arcticsun · 03-31-2006, 08:12 PM

Just a quick FYI. These "plugs" referenced here for torque specs is incorrect, there should only be ONE plug with that spec and its the 1/2" drive one (drain).

32.6 breaks the temp sensor plug. I dont know if this is common knowledge in this thread, but i certainly feel like an idiot now :/

**abdi** · 04-01-2006, 06:10 AM

Quote:

Originally Posted by Arcticsun

Just a quick FYI. These "plugs" referenced here for torque specs is incorrect, there should only be ONE plug with that spec and its the 1/2" drive one (drain).

32.6 breaks the temp sensor plug. I dont know if this is common knowledge in this thread, but i certainly feel like an idiot now :/

Good point! I hope you didn't break it.

11-06-2005, 03:51 PM	#1
Singletrack Spec C Club Car: 04 Impreza WRX STi Fav Mod: La Quarta Stella Location: Blitzburgh, PA Posts: 1,447 Join Date: Sep 2003 Trader Rating: (2)	What you need for a rear differential fluid change K0305Y0900 - LSD (75W-90 GLS), previously K0904AA080 004403010 - Three Bond 1105 (liquid gasket) Large adjustable wrench or corresponding socket (not sure on size) 1/2" breaker bar Hand Pump Fluid Extractor (optional) Torque spec on plugs: 49.0 N·m (5.0 kgf-m, 36.2 ft-lb) I drove the car up on ramps in the front, jacked the rear diff until the car was about level, and put the back on stands under the side jack points. Clean off the area around the plugs to keep any debris out of the diff; it will also make it easier to find any leaks. I pulled the top plug first (pull the sensor harness first) to make sure it wouldn't give me any trouble. Use a large spanner, adjustable wrench, or properly sized socket (I didn't measure). Some oil poured out (probably wasn't a 100% level), but not much. Put the plug back in so the oil wouldn't run into the bottom plug. I pulled the bottom plug (1/2 drive breaker bar) and drained the fluid. The fluid was BLACK (30k miles) and there was a fair amount of metal on the magnetic drain plug. I pulled a tiny bit more oil out of the bottom with the fluid extractor - not much though really. Replaced the bottom plug (with liquid gasket on the threads), pulled the top, and put the pump tube in. I got a pretty decent one that has some teeth to hold onto the threads in the diff. Pump like a madman. Mine took about .9liters before it started running out of the diff. Replaced the top plug (with liquid gasket). NOTE: At least 2 people have broken their top plug with the sensor. I am not sure what the cause of these failures actually was, but make sure you do not over-apply the liquid gasket and then over torque the top plug. The gasket acts as a lubricant and WILL affect the torque wrench to some extent. Covering the threads from the halfway point to the head of the bolt is probably sufficient. This ad is not endorsed by this member. Please register or login to hide this ad. Last edited by Singletrack : 09-20-2006 at 08:05 PM.

11-07-2005, 06:27 AM	#3
jsh139 How YOU Doin? Car: 2006 Audi S4 Fav Mod: OMGHI2U! Location: Philly 'burbs Posts: 7,719 Join Date: Apr 2004 Trader Rating: (8)	Good call on loosening the filler plug first Imagine draining out all the diff oil and then not being able to fill it because the filler plug is seized! Last edited by jsh139 : 11-07-2005 at 10:05 AM.

11-06-2005, 11:39 PM	#2
STi05' The Next Petter Solberg Car: 05' STi CGM/Silver Fav Mod: Recaro Sports Location: Mercer Island, Wa Posts: 976 Join Date: Oct 2004 Trader Rating: (1)	Do you think it would be worth while to say run on that oil for a 100 miles or so, then change it again? That might make sure you flush out all the old oil and filings. Just a thought.

01-11-2006, 04:23 PM	#8
qingshan Junior STI Driver Car: Fo/Sti 06/05 Fav Mod: autodim Location: SoCal Posts: 54 Join Date: Apr 2005 Trader Rating: (0)	[quote=Singletrack]K0305Y0900 - LSD (75W-90 GLS), previously K0904AA080 004403010 - Three Bond 1105 (liquid gasket) Large adjustable wrench or corresponding socket (not sure on size) 1/2" breaker bar Hand Pump Fluid Extractor (optional) Torque spec on plugs: 49.0 N·m (5.0 kgf-m, 36.2 ft-lb) I I pulled the top plug first (pull the sensor harness first) to make sure it wouldn't give me any trouble. How does that sensor get pulled

01-11-2006, 07:20 PM	#9
qingshan Junior STI Driver Car: Fo/Sti 06/05 Fav Mod: autodim Location: SoCal Posts: 54 Join Date: Apr 2005 Trader Rating: (0)	Thanks - I got it done Mobile Syn in the diff, trans lube next with my Kartbot ss install

02-22-2006, 09:32 PM	#11
Horatio Lurker Posts: 7 Join Date: Sep 2004 Trader Rating: (0)	Nice post Singletrack I just got done reading this and the trans thread and wanted to say thanks for the heads-up on the gasketsfor the trans, along with pointing out the appropriate liguid gasket. I did some checking and was a bit surprised that the Three Bond Subaru recommends for the rear diff is not the same as Permatex ultra grey. Glad you brought it up otherwise I am certain I would have used the wrong stuff without having any clue. I know there will be people saying no big deal, and they may be right, but why risk it when Subaru specifically endorses Permatex ultra grey as an appropriate substitute for a host of other applications, just not for the rear diff. Thanks again. (no, I am not posting appreciation in both threads)

03-25-2006, 11:16 AM	#12
dareseven Professional STI Driver Car: Sold 06 Aspen White/ Fav Mod: Meticulous Maintenance Location: AL Posts: 412 Join Date: Dec 2005 Trader Rating: (0)	Excellent write up. Much appreciated.

03-31-2006, 08:12 PM	#14
Arcticsun Junior STI Driver Car: 08 Aspen STi Location: Leesburg, VA Posts: 126 Join Date: Jan 2006 Trader Rating: (0)	Just a quick FYI. These "plugs" referenced here for torque specs is incorrect, there should only be ONE plug with that spec and its the 1/2" drive one (drain). 32.6 breaks the temp sensor plug. I dont know if this is common knowledge in this thread, but i certainly feel like an idiot now :/