Not 100% sure, but I think the front and rear diff on the '15 is the same as the '13, and mine was fairly easy. The front diff is a little different from the rear though. There are just a couple important items to keep in mind.

First, make absolutely sure that you have the right drain plug. Many here have accidentally drained the CVT. On mine, it is clearly marked around the outside edge of the pan. Just take your time and look and you will be OK. The drain is on the bottom. The fill is up on the driver side close to the half axle. The second thing that's a little different on the front diff is that it has a fill overflow plug.

So, open the fill and the drain and drain the gear oil, then put the drain plug back in and torque it. Next remove the fill overflow plug. Now you fill with fresh gear oil through the fill plug until gear oil starts running out through the overflow. Wait until the gear oil running out of the overflow comes to just a small drizzle, or even just dripping, then put the overflow plug back in and torque it. Put the fill plug back in, torque it and you are done.

It is kind of tricky to fill with new oil while watching the overflow. I recommend getting a gear oil hand pump. Get one that has a plastic nozzle on the end with the little plastic springs on the side that holds it in the fill. Then you can pump the fluid from below and watch the overflow easier. I bent a piece of copper tubing and put it on the end of the pump hose. This hangs in the fill hole. I haven't used it yet, but it should make the job a lot easier when I do my 60k service.

 

Thanks a lot for that information. Yeah, the drain plug is a t70 that is pretty clearly marked. I was mainly looking on the passenger side for a fill as that's where it was located on some previous gens I have seen write ups about. Can anyone comment on where the fill plug and the overflow plug are located? Any pictures or diagrams?

Thanks.

 

Perhaps this correct. I am going to poke around tomorrow to confirm: http://www.subaruoutback.org/forums/66-problems-maintenance/50954-2013ob-2-5i-cvt-transfercase-frontdiff-oil-change.html#post489768

 

From the 2016 Subaru Outback Service Manual.

 

IME you can buy the services that are actually called for, in the maintenance schedule in the warranty booklet, as ala carte items for a lot less than the mileage label packages sold by the dealer.

Even with just an oil change they give me a sheet showing inspection items performed, at least where I go they always inspect I guess because this is a way to find problems and billable work whether the car is in warranty or not.

 

I dont disagree, but you are still paying an arm and a leg for their hourly rates - for something as simple as an oil or a diff fluid change, it's not worth it to me. For something more complicated, perhaps.

These are the same people that want to charge you like $75 to change a cabin air filter...

I dont hate them because they need to make money (and they make next to nothing selling new cars), but just my thoughts.

 

I did the front and rear differentials on my 2013 OB. Your right the rear is really simple. There are steel sealing washers that you can reuse. There's some crap about using some high temp sealant on the threads. You don't need to do that it seals just fine using the torque shown on the maintenance procedure.

I have a new take on the front however. After I went thru the trouble of changing my front differential I was in for my free oil change. I was talking to the tech and he told me they didn't use the fill hole. He said they pulled the plugs on the drain and then on the overflow hole on the bottom of the front Diff. After giving it some time to drain they reinstalled the drain plug and then filled thru the over flow hole. The tech told me they push a plastic tube up the overflow hole and then push several inches of tubing into the hole to get it away from the overflow hole. Pump it full and when it starts coming out the same hole you are filling it with they remove the tube and when it the flow starts slowing down they put the plug back in. I'm never going to use the fill hole again>

Also never replaced the washers on the front Diff. Sealed just fine using the torque listed. No sealant either

 

Interesting. Yeah, that could work. I have a hand pump but I am thinking the diameter is a bit large for the overflow hole. I can definitely see that being easier (and also if you are working under a lift, probably the better way)

 

What weight does Subaru recommended for Gear Oil? What's everyone's take on using synthetic and changing it less often?

How much does the front and rear diff take?

 

75w90 - needs to be GL-5 rated, which is just about any name brand. You need about .75 quarts in the rear and about 1.5 in the front. Not sure what's in there from the factory, but it's likely filled from the factory with synthetic. Folks will argue with Conventional vs Synth on different applications/cars but the main thing is following what the dealer recommends and change it often. Id rather have a car with a well changed dino oil than someone who just leaves synthetic in there and assumes that it's fine. Synthetic holds up to higher heats better and you can get a wider variety of weights (for instance, I dont think there is such thing as 0w20 weight conventional oil that the 2.5 runs on, at least readily available). That said, I am not a mechanic or a scientist. I do know that I use conventional oil on older engines as the synthetic seems to create more leaks and weeps.

 

GL-5 gear oil; 75W85 (or 75W90).

I have synthetic ready to be added.

Rear takes 0.8L and front takes 1.3L according to the service manual.

 

GL-5 gear oil; 75W85 (or 75W90).

75w90 - needs to be GL-5 rated ...

GL-5 (75W-90) is correct for the rear differential for all models.

But the 2015 Legacy/Outback FSM specifies SUBARU GEAR OIL EXTRA MT (or equivalent) for the front differential in all models. For the high-torque G1 (TR690) transmission mated to the 3.6 engine the FSM notes:

Recommended fluid: SUBARU GEAR OIL EXTRA MT
CAUTION:
If an alternative transmission oil is used, you may not have expected functionality and performance.
Alternative fluid: GL-5 (75W-90)
[emphasis in original]

In my experience, transmission and differential fluids are one place that it's wise to follow manufacturers' recommendations to the letter. These days a lot of modern transmissions and gear sets are designed around the characteristics of very specific lubricant formulations, and substituting generic fluids involves substantial risk.

 

Thanks for the replies, very helpful information. Would Extra-S 75W-90 be the same or equivalent? Subaru Extra-S 75W-90 High Performance Gear Lube | FastWRX.com I found the SUBARU GEAR OIL EXTRA MT but it only comes in 5 gallon increments which isn't the most friendly for individuals 2014 Subaru. #SOA748V0100: Gear Oil Extra MT 75W80. 5 Gallon Pail

 

They are both equivalent. Earlier, the quart version was not available and Subaru sold Extra-S oil only in 5 gallon pails.

 

I used GL-5 75W-90 for both front and rear. This is exactly what the Subaru manual recommends for the front differential on a '13 with the CVT. It does call for a different fluid in the front diff on a '13 with the MT. I don't know what the difference would be between the '13 and '15, as I thought the differentials were identical.

For me, the decision to go with synthetic has little to anything to do with extended service intervals, but much more to do with improved performance in cold weather conditions. I've done a lot of research on this subject, including watching videos of lab tests by leading lubrication manufacturers, and the evidence is overwhelming that using dino (conventional) gear oil in cold weather results in lack of proper lubrication, loss of fuel economy, and sluggish starts. If you live in the sun belt then perhaps conventional is a good call. But I would strongly recommend synthetic gear oil in the differentials for anyone who lives in a cold winter climate.

From the discussions I have read here, by far the most popular choice is Red Line followed by Mobil 1 and Valvoline Synpower. I chose Mobil 1 and I have had good luck with it. For a small SUV/wagon I don't see any purpose for a high performance lubricant like Red Line. Perhaps if you go off road weekly it would be worth the extra coin to go with Red Line. But under normal use, it isn't going to offer any more protection.

 

I'm not the one that needs to re-read this. Troll


11.FRONT DIFFERENTIAL GEAR OIL
















Recommended fluid: SUBARU GEAR OIL EXTRA MT
CAUTION:
If an alternative transmission oil is used, you may not have expected functionality
and performance.
Alternative fluid: GL-5 (75W-90)


When replacing a rear differential assembly, select the correct one according to the following table.


NOTE:


• Using a different rear differential assembly will cause the drive train and tires to drag or emit abnormal


noise.


• For option code, refer to “ID” section. <Ref. to ID-2, IDENTIFICATION, Identification.>




Model


Sedan OUTBACK


2.5 L 3.6 L 2.5 L 3.6 L


CVT 6MT CVT CVT 6MT CVT


Rear differential type VA1-type T-type VA2-type VA1-type T-type VA2-type


Identification Y2 B1 Y4 Y3 B4 Y4


LSD type —


Type of gear Hypoid gear


Gear ratio (number of gear teeth) 3.900 (39/10) 4.111 (37/9) 4.111 (37/9) 4.111 (37/9) 4.444 (40/9) 4.111 (37/9)


Oil capacity 0.8 L (0.8 US qt, 0.7 Imp qt)


Rear differential gear oil GL–5 (75W–90)

 

I'm not the one that needs to re-read this. Troll

Calm down.
Mis-reading something, or an omission, an oversight, incorrect info, having a differing opinion, etc does not make one a troll. Better to look up the definition of a word before using it lest one appear to not know what they're talking about.

BTW, posting in bold font and/or all caps is considered shouting and exhibits poor internet etiquette. On some sites, it's even against the rules.

Peace.

 

Some very interesting information in this thread. Having had the original front & rear diff oils in our Australian spec 2016 3.6R Liberty replaced with Castrol Syntrax Universal Plus 75W-90 I decided to look further into this.

USDM Vehicles:

To me the 2016 USDM Legacy & Outback Owner’s Handbook spells it out reasonably clear for the CVT models.

The below is taken from the USDM Legacy & Outback Owner’s Handbook.
Front Diff:
• Subaru Extra MT (The vehicle is filled at the factory with this type of manual transmission oil/front differential gear oil).
• API classification GL-5 (75W-90) (You may use this type of manual transmission oil/front differential gear oil. However, using this type of oil will detract from driveability and fuel efficiency).
Rear Diff:
• API classification GL-5 (75W-90 recommended).

It is interesting that the 2015 USDM Legacy & Outback FSM is worded differently for the front diff oil in the TR690 (HT) CVT models & the TR580 (Standard) CVT models. For the front diff oil in the TR580 CVT model is just states ‘SUBARU GEAR OIL EXTRA MT or equivalent’, whereas it goes into more detail for the front diff oil in the TR690 CVT models (see ammcinnis' previously posted links).

Australian spec Vehicles:

The Liberty & Outback Owner’s Handbook that came with our Australian spec 2016 3.6R Liberty indicates the following for the front & rear diff oils in the CVT models (no mention on that table about manual transmission). Note that it doesn’t give the preference or warnings that the USDM Legacy & Outback owner’s handbook gives.
Front Diff:
• Subaru Extra MT (Equivalent to factory-filled oil).
• API classification GL-5 (75W-90 recommended).
Rear Diff:
• API classification GL-5 (75W-90 recommended).

On the previous page to this it covers the manual transmission oil (obviously for the diesel manual) with no mention about the front & rear diff oils.
This indicates for the manual transmission oil (Note the preference & warning for the manual transmission oil).
Manual Transmission:
• Subaru Extra MT (Equivalent to factory-filled oil).
• API classification GL-5 (75W-90). (You may use this type of manual transmission oil. However, using this type of oil will detract from driveability and fuel efficiency).

Subaru Australia on their website recommends Castrol Professional oils for the engine (they don’t mention recommended brands for front or rear diff oils though).
On the Castrol Australia website, both the front & rear diff oils recommended for the 2015-2017 Liberty 3.6R CVT model are: CASTROL UNIVERSAL 80W-90 or CASTROL SYNTRAX UNIVERSAL PLUS 75W-90. This is on the Castrol retail oil selector guide & also on the Castrol trade oil selector guide.

After this I feel confident using Castrol Syntrax Universal Plus 75W-90 in both the front & rear diffs of our Liberty.

I'm not sure why the information for USDM Outbacks & Legacys is different (unfortunately I don't have an Australian spec FSM for further comparison). Perhaps the Subaru Extra MT oil being 75W-80 is more suitable for a colder climate, or perhaps it gets rid of the heat quicker – just a guess.

 

Not sure how this came about.... The factory uses their "own" gear oil, which I am told is conventional (I specifically asked the dealer if they used synthetic in diffs, no was the reply). If so, the viscosity is likely 80w-90.

Anyways, front diff of an auto transmission needs a GL-5 rated diff oil, either conventional 80w-90 or synthetic 75w90. Doesn't matter which. Same type for rear.

If I had a manual transmission, I would not stray from using Subaru extra-s gear oil (FSM states this, I think is is a synthetic oil), clearly it works well with the synchros. What I've read on manual trans and other gear oils is there may be some incompatibility, seems like an at own risk.

 

Does anyone have the Subaru part #s for the crush washers for the front & rear differential drain and fill plugs? I pretty sure the rear is # 80391860 for 2 each.

 

They are not crush washers, just steel washers. I reused mine, no leaks. Lots of people on here reuse them multiple times.

 

I have not been under my 17 yet but in the past with my 01 3.0 and 09 3.0 you just drained from the bottom of the differential and filled through the dipstick. I don’t have the service manual yet for my 17 but looking at the 16 service manual that was posted, I see there is a drain, fill and separate overflow. Sure seems silly, why change something that worked and gave an option to check with a dipstick. I can understand taking away the dipstick, most differentials don’t have one anyway but why not have the fill be the overflow as well.

 

Sure seems silly, why change something that worked and gave an option to check with a dipstick. I can understand taking away the dipstick, most differentials don’t have one anyway but why not have the fill be the overflow as well.

If you make servicing the part or even checking fluid levels more inconvenient, the idea might be that they'll fork over money at the dealer to have it done for them?

Same with the transmission, no dipstick and as a result I cannot easily check the level or condition of the fluid. It's a pain and a tight fit under the car to get to the fill hole.

 

Why can't people behaved like civilized adults? Why?

 

Am I missing something? My maintenance schedule doesn't even call for differential service at 30k miles. Is this being done early due to severe driving of some sort?

Andy

 

Not done for any reason other than some of us are anal about clean fluids and maybe have nothing better to do!

Ok, I'm convinced the front diff needs the special Subaru MT oil, but where do you get it in quart bottles? Is this something the dealer stocks?

If it's what you want, sure. I'm guessing you have a CVT trans, if so you don't need any special gear oil. It just needs to be a GL-5 diff oil, synthetic 75W90 or conventional 80W90. You'd have to call your local dealer. I know mine doesn't sell any fluids because they buy in bulk drums.


Word of caution for anyone who's going to do the front differential drain/fill, make sure you add new gear oil to the front differential and NOT the CVT. If for some reason it was put in the CVT, tow it to the dealer.

 

Ok, I'm convinced the front diff needs the special Subaru MT oil, but where do you get it in quart bottles? Is this something the dealer stocks?

 

As far as I can determine, Subaru Gear Oil Extra MT (SOA748V0100) is only available in 5-gallon pails. Some owners have reported that their dealer was willing to dispense it by the quart into customer-provided containers. Expect to pay about $25 per quart, though. (MSRP for the 5-gallon pail is $420.00.)

 

See attachment, direct from the 2015 Legacy/Outback Warranty and Maintenance Booklet:

 

FYI: Redline makes a 75w/80 synthetic MT lubricant, which most likely matches the Subaru Extra MT(not to be confused with Extra S)front diff fill.
https://www.amazon.com/Red-Line-Transmission-Transaxle-Lubricant/dp/B000CPCBEG

 

ammcinnis,

lloyd123,

Thank you both for the info. Makes more sense than what I had found online.

I feel better now. I was stressed. LOL! I was thinking I was due for something that I am incapable of taking care of the way I like to.

I'm probably a month away from being able to do my own work again.

Andy

 

So I've been away for a few days because this thread got sideways. In summary, can anyone answer the question definitively in a simple one-line sentence? I have a 2015 USA version Outback, 2.5L. What gear oil is called for in the front differential? Perhaps I missed it in the last 10 posts or so, if so please forgive. I just want to get the right stuff in my car.

Subaru MT or GL5 75w/90? I will call the dealership this week but I suspect the answer will be just as convoluted as a thread..... or I might get different answers depending on who I talk to, an actual technician, a Salesman in the parts department or a service manager.

Perhaps the fluid that they call MT is basically unavailable anywhere else. Knowing that, they make a secondary recommendation with the caveat that performance or gas mileage may be affected slightly. Every manufacturer is under big pressure to maximize gas mileage every way they can.

 

... can anyone answer the question definitively in a simple one-line sentence? I have a 2015 USA version Outback, 2.5L. What gear oil is called for in the front differential?

Previously asked and answered: "SUBARU GEAR OIL EXTRA MT or equivalent." Source: see attachment.

 

FWIW, my local dealer gave me a shrug when I asked for EXTRA MT! They didn't stock it and said they refill it with GL-5 gear oil. I used Redline when I did mine.

 

Yeah I just talked to the parts department at my local dealer. They say they use 75-90 and never use the MT fluid for anything.

I'm waiting for a call back from the service manager to see what he knows about this.

I cannot believe something so stupid simple can be so complicated. Next call will be to corporate headquarters and I'm sure they won't have a clue. I think the bottom line is everyone uses gl-5 but Subaru had to put a disclaimer in their manuals saying it might affect gas mileage and or performance simply because everything they do design and engineering wise is from the perspective of trying to eek out every mile per gallon. The gl5 is probably perfectly acceptable and probably is what goes in 90% of all the cars after the factory fill. You might lose a tenth of a mile per gallon who knows

 

I did the full service in mine at 25k for both diffs, trans, engine oil, oil filter and cabin filter, then took at 2500 mile trip to Texas and got the best mileage 29.6 mpg after the service. I agree they (SOA) put the foot note to cover their hindparts!

 

Okay, I'll ask the question. What gear oil did you put in the front differential haha

 

I used Redline MTL 75W-80 in front, Redline 75W-90 in the rear and Redline CVT fluid in the trans.

 

I used Redline MTL 75W-80 in front,.

And your car did not explode? [emoji33]