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2016 Subaru Outback 2.5i Limited
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192 Posts
Discussion Starter #1
I just spoke to a Mobil 1 technical support person who reported that Mobil 1 does not recommend using their gear oils in any Subaru products! He reported that although it does meat the GL-5 requirements, Subaru uses softer metals in the manual transmission trans-axle, and the sulfur additives will eat the syncros. The Guy reported that Mobil has more claims than he can remember repairing or replacing Subaru manual transmissions. I find this out after spending $55 on refilling everything on my 2006 2.5i with Mobil 1!!!!! He said the use of engine oil is no problem, only the manual transmission. The dealership service department seconded this, and said Subaru uses a semi synthetic oil. Off to the dealership tomorrow for another drain and refill! I am really bummed, since I switched 1500 miles ago, I have been averaging 31.4 mpg.

Kona:8:
 

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Gallery Ninja, ,
2004 Outback "Bluebaru" & 2005 Outback XT
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5,195 Posts
Provided all this is legit, should we sticky this considering the repercussions?
 

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2016 Subaru Outback 2.5i Limited
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192 Posts
Discussion Starter #3
Verified!

I just verified this with another Subaru Dealership. I just feel sick, and hope nothing has been damaged. The Mobil 1 tech guy also said that the condition is made worse by heat such as racing. I believed all GL-5 oils were the same!

Great photography site, I am a "photo buff" myself.
 

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Gallery Ninja, ,
2004 Outback "Bluebaru" & 2005 Outback XT
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5,195 Posts
Hey Kona,

any chance you have any paperwork or statements made by Mobil?

and curious, is the issue due to the type of oil being used, specifically GL-5 ATF vrs. Type-F or some other standard? Er, let me rephrase.

What is type of oil does your Subaru require?


--------------------

As to Photo's, yah, come on over to our sister site. Lots of us Subarunuts are over there including the sites founder (FastSly on this board). Post up some photos and say hello :29:
 

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2016 Subaru Outback 2.5i Limited
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192 Posts
Discussion Starter #5
Mobil 1 Gear Oil

The person I spoke to at Mobil is Matt ([email protected] or 1-800-662-4525). My 06 OB MT and dif require API GL-5 gear oil, which is exactly what Mobil 1 gear oil is according to the web site and bottle. Matt even verified that it is the correct oil for this application, he just said the soft gears in Subaru Transmissions are damaged by the sulfur in the oil. From his report that Mobil is tired of funding repairs for Subaru transmissions. Again, he did say this occurs mostly under high heat situations, but was aware of trannys being damaged under normal driving conditions. I may contact Mobil to find out if they would be willing to cover the cost of the gear oil I had purchased, and the cost of the change out at the dealership tomorrow since it is posted no where about this.
 

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Premium Member
2004 Outback Wagon, Mystic Blue Pearl
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4,945 Posts
I am getting close to time for servicing all of those components, and I am wondering if there are problems with any other synthetics. I hear a lot of people using Redline, and I have wondered about Royal Purple, but it sounds like there is not a clear way to tell whether a particular oil might have the same problems.
 

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Superb Moderator, ,
MY12 WRX, MY07 FXT
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6,186 Posts
I was told to stay away from Mobil 1 for the tranny also. I love the M1 in the crankcase, but that's it.

I have Motul Gear 300 in the manual tranny and rear diff--great stuff.

Brian
 

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2002 WRX MBP
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1,105 Posts
Over on the Impreza site, many people say to avoid synthetics period in the 5MT. Several there have also posted about talking to Mobil and being told not to use Mobile 1 in Subaru transmissions. According to the threads I've read over there, it's mostly the 5MT that has trouble, the 6MT of the STi is apparantly OK with synthetic. He's a quote from over at NASIOC about tranny fluids.

The Subaru 5MT can be a picky about what fluid you should use. Popular fluids that have a large fan base are:

a. OEM fluid AKA non synthetic 75w90 gear oil
b. Uncle Scotty's Cocktail of 1qt Redline lightweight shockproof, 1qt Pennzoil or GM Synchromesh, 2qt Castrol HypoyC 80w-90.
c. Full Redline lightweight shockproof

While we are big fans of sticking to OEM fluids on NASIOC, this is one case where using something not SOA recommended has shown actual benefit, mainly in helping with synchro interaction.

You 6MT users can use whatever you like, though there is some benefit by using one of the above fluids as they do aid in synchro engagement.
A lot of people over there swear by Uncle Scotty's cocktail. I haven't tried it myself, yet, but I'm considering it whenever I get around to changing the fluid in my 5MT.
 

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2001 Outback 5 speed, 2000 Outback Automatic, 2002 Legacy Wagon Automatic. All 2.5L
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270 Posts
Good info here. I was going to use M1 on my last tranny oil change but it was out of stock. :D
 

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98 outback 5spd MT, the mighty Huc
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im runnning uncle scottys cocktail and its been great, after about 500miles things really got nice and this part winter cold shifting was so much easier.

however, my friend (username dj paulie around here) went to it in his '02 outback and didn't notice much difference.
 

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2016 Subaru Outback 2.5i Limited
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192 Posts
Discussion Starter #12
Happy ending

I had the dealership drain and refill the transaxle and diff yesterday at the cost of $90 which is better than the cost of a new tranny. Mobil has agreed to refund me the purchase price of the 5 quarts of gear oil I has put in the subaru so it ends well.
 

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Superb Moderator, ,
MY12 WRX, MY07 FXT
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6,186 Posts
And Mobil is paying you back? Wow. That's great.

Brian
 

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2002 Outback - 5 spd. all stock - for now.
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121 Posts
yessir, i'm runnin scotty's in the transmission, and mobil 1 in the engine, with no noticeable ill effects so far..

i know i'm one of the few whose car doesn't eat any oil between changes..

if it's broke don't fix it? or should i be worried?
 

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'02 H6 Sedan - gone :(
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169 Posts
being a user of synthetics, this is the first i have heard of this... i currently use M1 in the crank as well... i currently have amsoil in the tranny (auto) without any problems (35k miles... knock on wood)

definitely good info
 

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2001 Outback 2.5L Wagon
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255 Posts
In light of reading this..... none of it deals with auto tranny's.

Any recommendation on what to use in an auto tranny and differentials in a 2001 OB?
 

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01 H6, 04 2.5, 72 Sonnett
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90 Posts
Oil

I used Amsoil throughout on mine (257,000 miles) [AT] with no problems. on a previous Subaru I had a transmission seal problem when using Mobil 1.
 
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