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Tranny and rear differential fluids?


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After searching and reading of a quantuty of discussions regarding the most appropriate fluids for manual transmission and rear differential I am still indecided with which ones to go. I mostly use my LGT for commuting on a highway and it looks like in my case the Redline's 75W90NS for transmission and 75W90 for rear diff is the most recommended. Do you guys have any better ideas? Thanks a lot.

 

 

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Definitely a solid pic! You have a few other options as well. Specialty formulations Inc., & Silkolene Syntran5.

 

I personally use the SF MTL-R & HDS-5, for my trans & diff. I love them! All the oil's mentioned are about the same in price, so I guess availability or personal preference will decide what you get.

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  • 2 weeks later...
Just a little tid bit here. I ordered the SF trans fluid and rear diff oil. I went under my car to check out how to drain my trans oil, and there was the dreaded torx T70 bolt. I know of several industrial supply & auto stores in the area, but everybody acted like I was making something up about a T70 torx bit. Biggest they had across the board was a T60. Bottom line is, if you don't have the bit already, you might want to order one before or at the same time as the replacement fluid, don't count on your local auto parts store having it. NASIOC recommends Northern Tool, as I ordered their 19 pc. 1/2" drive kit, 29.99 plus shipping, and every bit you'll every need from Camcar Textron. ;)
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Anyone know what the stock, factory fill oil is for our manual trannys and diff?

 

Edit: Based on my search, it appears that the stock, factory fill for our trannys/diffs is *possibly* Valvoline. Anyone know for sure?

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More things to get before you mess with this: Fluid pump. The trans oil fill neck is underneath the IC and right next to the turbo/downpipe. You will need a fluid pump to get the oil in there. Didn't know where else to post this, and sorry is this is obvious to everyone but me.
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Keefe, do you use 75W90NS for your tranny? How often do you change your fluids?

 

Yes. every 15k miles or once a year (which ever comes first) cuz I drive that much harder. 30k miles is ok too if you just want to go by mileage, but I wouldnt go two years without changing it.

 

I also get the 75w90 with the differential additive for the rear diff.

 

Keefe

Keefe
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More things to get before you mess with this: Fluid pump. The trans oil fill neck is underneath the IC and right next to the turbo/downpipe. You will need a fluid pump to get the oil in there. Didn't know where else to post this, and sorry is this is obvious to everyone but me.

 

Fluid pump?!? :eek: what??! :confused: it's called a flexible hose funnel, you dont need a fluid pump.. Just pour it in and let gravity do the work.

 

As for the rear diff, just get a squeeze bottle or an oil gun.

 

 

 

Keefe

Keefe
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I changed over to Redline 75-90 NS a couple days ago. The feel is a little better while shifting (at 80 farenheit it's hard to tell), but what I noticed immediately was the reduced noise from the gearbox, particularly during low speeds through the neighborhood (2nd gear around 2500 rpm). What I'm looking for is easy shifting on winter mornings, and added protection for the transaxle/diff. Flexible tubing on the funnel works fine....just let things cool down before the refill.
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Yes. every 15k miles or once a year (which ever comes first) cuz I drive that much harder. 30k miles is ok too if you just want to go by mileage, but I wouldnt go two years without changing it.

 

I also get the 75w90 with the differential additive for the rear diff.

 

Keefe

 

What is the diff add? Does it come already in the redline product or does it need to be added after?

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The center diff is Viscous. The rear diff in our cars is Limited Slip... with clutches.

 

Wrong. The 2005 LGT with 5MT trans uses a sealed viscous clutch in both the center diff and the rear diff, as stated in the sales brochure and at Subaru's web site.

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Wrong. The 2005 LGT with 5MT trans uses a sealed viscous clutch in both the center diff and the rear diff, as stated in the sales brochure and at Subaru's web site.

 

I stand corrected. I saw limited slip and assumed clutches...my bad.

The Subie site confirms viscous limited slip rear.

 

Thanks for clarifying.

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I changed over to Redline 75-90 NS a couple days ago. The feel is a little better while shifting (at 80 farenheit it's hard to tell), but what I noticed immediately was the reduced noise from the gearbox, particularly during low speeds through the neighborhood (2nd gear around 2500 rpm). What I'm looking for is easy shifting on winter mornings, and added protection for the transaxle/diff. Flexible tubing on the funnel works fine....just let things cool down before the refill.

 

 

I noticed that shifting just got smoother (I feel that my revmatching and the syncros are working at a more efficient level).. I know stock fluids are 80w90 or something like, I doubt the 75w90 has something to do with it, it might it might not, but I doubt anyone can tell the difference of a difference in cold weight of 5.

 

 

Keefe

Keefe
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What is the diff add? Does it come already in the redline product or does it need to be added after?

 

You can buy it as an additive or you can buy the bottles that already have the addtive in there:

 

75w90:

http://www.redlineoil.com/products_gearlubricants.asp?pvID=81&prodID=60&subcatID=20

 

75w90NS (non-slip):

http://www.redlineoil.com/products_gearlubricants.asp?pvID=82&prodID=60&subcatID=20

 

and the Additive:

http://www.redlineoil.com/products_gearlubricants.asp?pvID=112&prodID=60&subcatID=20

 

I didnt get the 80w140 because my gears will never get that hot (so why need a gear oil that thick right?)

 

 

Keefe

Keefe
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You can buy it as an additive or you can buy the bottles that already have the addtive in there:

 

75w90:

http://www.redlineoil.com/products_gearlubricants.asp?pvID=81&prodID=60&subcatID=20

 

75w90NS (non-slip):

http://www.redlineoil.com/products_gearlubricants.asp?pvID=82&prodID=60&subcatID=20

 

and the Additive:

http://www.redlineoil.com/products_gearlubricants.asp?pvID=112&prodID=60&subcatID=20

 

I didnt get the 80w140 because my gears will never get that hot (so why need a gear oil that thick right?)

 

 

Keefe

 

From what I can see then buy the 75w90ns stuff for the tranny and the 75w90 for the diffs and you already get the additive in the bottle, correct?

 

No need to buy the additive then.

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You can buy it as an additive or you can buy the bottles that already have the addtive in there:

 

75w90:

http://www.redlineoil.com/products_gearlubricants.asp?pvID=81&prodID=60&subcatID=20

 

75w90NS (non-slip):

http://www.redlineoil.com/products_gearlubricants.asp?pvID=82&prodID=60&subcatID=20

 

and the Additive:

http://www.redlineoil.com/products_gearlubricants.asp?pvID=112&prodID=60&subcatID=20

 

I didnt get the 80w140 because my gears will never get that hot (so why need a gear oil that thick right?)

 

 

Keefe

 

Why are you using a "limited slip friction modifier" additive? I have used the Redline additive in the past, on a 4WD truck with a clutch type LSD in the rear end, and it worked well to reduce clutch-pack chatter. Since the Legacy does not use a clutch pack in the rear diff, it seems to me that the additive is totally unneccesary.

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It's just as a reference for those who wish to, especially the people that are thinking about using Cusco LSDs and the sort. But you dont have to add much of the additive to keep the stuff slippery enough. Some people even buy the non-added slip stuff and wish to add their own amount, to each their own.

 

Keefe

Keefe
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