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2010 Subaru Outback 2.5i Premium (The Superoo), Graphite Gray Metallic, CVT, Yoko Geolandar G015 AT 225/65R-17
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Discussion Starter · #1 ·
I know this is probably just a "pick one" kind of choice, but I thought I would ask...

What power steering fluid do you use? I know besides the Subie brand fluid, my manual says Dexron III fluid is approved. But like most oil, there are synthetic and mineral (conventional?) Dextron III fluids. Am I correct then to assume that it doesn't matter which one I put in? I'm about to do a flush, so I want to make sure I'm not making any flawed assumptions.

I went to walmart and picked up some Castrol Import Multi-vehicle (ATF) fluid as that was the only thing that appeared to be compatible, but I'm thinking I'm going to swing by Advanced Auto and pick up something else instead.

Anyway, what's the recommendation?
 

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2012 OB , 2017 Impreza
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3,657 Posts
I have been running Valvoline MaxLife Synthetic in the red bottle from WallyMart in all my Subies.

I looked up the specifications at that Castrol Import Multi-vehicle (ATF) and it claims to be compatible for Subaru PS system.
 

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2013 Outback, 2.5i Limited w/ Moonroof
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I've been using Mobil 1 ATF. But I bought Castrol Transmax for the next change. Living in a climate with cold winters, I decided to go with a synthetic fluid for better flow in the cold weather.
 

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2012 OB , 2017 Impreza
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I've been using Mobil 1 ATF. But I bought Castrol Transmax for the next change. Living in a climate with cold winters, I decided to go with a synthetic fluid for better flow in the cold weather.
I fully agree with the use of synthetic to flow better in cold weather. I do not care for stiff steering during -10F mornings. Be aware that ALL modern ATF is synthetic-based. (DEXRON-VI (GM), ATF+4 (Chrysler)...etc)

Be careful with the Castrol Transmax: There are exactly 9 different types of Castrol Transmax... many of which are NOT comparable with Subaru Power-steering systems. If it does not clearly say "Dexron III" or above.... DO NOT USE IT.

You can see them all here ==> ATF, Automatic Transmission Fluid | Transmission Fluids (ATF), Brake Fluids, Greases and other lubricants for your Car | Castrol - Motor Oil, Engine Oils, Full Synthetic Oil, Transmission Fluid and Lubricants
 

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2013 Outback, 2.5i Limited w/ Moonroof
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I fully agree with the use of synthetic to flow better in cold weather. I do not care for stiff steering during -10F mornings. Be aware that ALL modern ATF is synthetic-based. (DEXRON-VI (GM), ATF+4 (Chrysler)...etc)

Be careful with the Castrol Transmax: There are exactly 9 different types of Castrol Transmax... many of which are NOT comparable with Subaru Power-steering systems. If it does not clearly say "Dexron III" or above.... DO NOT USE IT.

You can see them all here ==> ATF, Automatic Transmission Fluid | Transmission Fluids (ATF), Brake Fluids, Greases and other lubricants for your Car | Castrol - Motor Oil, Engine Oils, Full Synthetic Oil, Transmission Fluid and Lubricants
Yes, Brucep is correct. Specifically, I selected Transmax Dex/Merc. It meets Dexron III requirements, which is what Subaru specs out for P/S fluid. But this thread got me thinking, so I looked up the Product Data Sheet for both Transmax Dex/Merc and Mobil 1 Synthetic ATF, and there is a very significant difference in viscosity at -40° C and cold pour point. Mobil 1 is far superior with a -40° C viscosity of 10,040 vs 17,000 for the Castrol. Pour points are -51° and -43° C respectively. Both have very similar viscosity at 40° C and 100° C.

Based upon this data, I would not recommend the Castrol in a cold climate application. I will be returning the bottle of Castrol and staying with Mobil 1 Synthetic ATF for P/S fluid in my Outback.

https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/68D5435223A1FD148025814500665523/$File/BPXE-ANM933.pdf

https://www.mobil.com/english-us/passenger-vehicle-lube/pds/glxxmobil-1-synthetic-atf
 

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2010 Subaru Outback 2.5i Premium (The Superoo), Graphite Gray Metallic, CVT, Yoko Geolandar G015 AT 225/65R-17
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236 Posts
Discussion Starter · #6 ·
This is why I love this forum. Exactly what I needed to know!

The Valvoline Maxlife is probably what I'll get. It was actually what I was originally going to get but my closest wallyworld was out of it so I settled on the Castrol. I just wish the Valvoline didn't cost twice as much! I could get three bottles of Castrol though for what it takes to get a bottle of the Mobile1 fluid.

Thanks again for the help!


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2013 3.6R Limited
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We live in a relatively moderate climate. I keep a quart of plain ol' Dexron III simply as a power steering fluid supply for three of our four vehicles. We have owned our Outback since early November 2015 and I do not recall ever having to top up its power steering fluid tank. I will have no hesitation in adding a bit of my Dexron III to the Outback if necessary.
 

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This is why I love this forum. Exactly what I needed to know!

The Valvoline Maxlife is probably what I'll get. It was actually what I was originally going to get but my closest wallyworld was out of it so I settled on the Castrol. I just wish the Valvoline didn't cost twice as much! I could get three bottles of Castrol though for what it takes to get a bottle of the Mobile1 fluid.

Thanks again for the help!


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From the product data sheet, it looks like Valvoline Maxlife ATF is comparable to Mobil 1 ATF. Another great choice. I would use this in my P/S.

https://sharena21.springcm.com/Publ...2d889bd3/0c5d0ab2-1976-e711-9c10-ac162d889bd3
 

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2010 Subaru Outback 2.5i Premium (The Superoo), Graphite Gray Metallic, CVT, Yoko Geolandar G015 AT 225/65R-17
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Discussion Starter · #9 ·
Did it earlier today while I had the car jacked up for an LCA bushing swap. Silly me, I forgot to plug the fitting for the return line the first time I filled it up. Precious Valvoline max life puddle on the floor :p

I had some minor groans in the steering when I took my post maintenance "victory lap" around the block. It did seem to go away though.


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2009 OB 2.5i SE 4EAT
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A while ago I topped off the res with PS fluid, oops. Not much, but it's overdue for a flush anyway.

I went to Wally and forked over a whole $19.xx (tax incl.) for a gallon of Valv Max Life synthetic ATF dex/merc. Cheaper than Amazon (you can only buy a 3 pack of the same product gallons on Amazon and ranges from $70 up... at the time of this posting).

Can someone link to a video or detailed walkthrough with pics of how to pump as much of the PS fluid as possible up from the rack and out of the system?

My ride is the 2009 Outback 2.5N/A (3rd gen)

edit: YES

http://www.subaruoutback.org/forums...guides/182002-power-steering-fluid-flush.html

This is what I was looking for. :) Good ol' search function...

Also this post:

http://www.subaruoutback.org/forums/5582353-post6.html

And this one (for a 2012, but the exact same idea):

http://www.subaruoutback.org/forums/104-gen-4-2010-2014/260602-changing-power-steering-fluid.html
 
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