[subi4justin]

hey there guys and gals. So its that time for me to change my transmission oil, and rear diff oil. Since this is my first time changing the oil in both, i've been doing research on what the best oil is for my 05. The problem i keep running into is the second i see someone saying one product is good, somebody else chimes in and gives there .02 on why that product is bad. I just recently picked up some Valvoline High Perfomance Gear oil 75w90, and i am a little hesitant to put it in. Is this the proper oil i should be replacing everything with?? If its not, can someone please point me in the right direction. Thank you all in advance
justin

[V8Huntr]

You're going to get the same kind of responses in here. The Valvoline oil is the OEM fluid so you can't go wrong with that. I've heard more pros than cons for Motul. I'm running Motul in my rear diff and plan to change my trans fluid soon to Motul 300.

[Cr8zyJAP07]

how often do you guys change transmission and diff fluid?

[subi4justin]

Originally Posted by V8Huntr

You're going to get the same kind of responses in here. The Valvoline oil is the OEM fluid so you can't go wrong with that. I've heard more pros than cons for Motul. I'm running Motul in my rear diff and plan to change my trans fluid soon to Motul 300.

thank you for your response and i figure i will get the same responses on this topic. I had read that valvoline was our OEM, so that makes me feel a little better. Are you running Motul Synthetic??

[subi4justin]

Originally Posted by Cr8zyJAP07

how often do you guys change transmission and diff fluid?

this will be my first time and i have had the car for a year now. My odometer say 43,xxx and i have no clue when it was changed before. I have heard every 30,000 miles??? give or take i think

[Mykl]

When I change the gear fluid I call a dealership and have them send me a jug of OEM fluid. IMO it's the best you can do. Very good stuff.


....and ever 30k miles is right.

[sujak]

Originally Posted by Cr8zyJAP07

how often do you guys change transmission and diff fluid?

manual says every 30,000

[r12rex]

Just changed mine yesterday.

Motul Gear300 75w90 Tranny/Diff
OEM Rear LSD Subaru Fluid

I changed my fluid at 16k...the rear diff was pretty filthy and tranny fluid was fairly clean...figured I'd change it since the the diffs and tranny were "breaking" in...I'll do it again at 30k then 60k etc. etc.

Kind Regards,
Ryan

[Deuce Cam]

Originally Posted by V8Huntr

You're going to get the same kind of responses in here. The Valvoline oil is the OEM fluid so you can't go wrong with that. I've heard more pros than cons for Motul. I'm running Motul in my rear diff and plan to change my trans fluid soon to Motul 300.

The oem transmission fluid is Subaru extra gear oil s 75W-90. I recently contacted SOA regarding what transmission oll they put in the USDM STi from the factory and I received this response:

The gear oil used by Subaru is SUBARU EXTRA GEAR OIL S 75W-90. The manufacturer is SHOWA SHELL SEKIYU.

The problem is it's nearly impossible to find a dealership that uses this fluid or even knows what it is. Subarugenuineparts.com sells it in a 5 gallon drum for $135 + shipping, hardly practicle.

Mykl, I'm assuming you found a dealerships that will repackage and ship this oil in smaller quantites? If so, would you mind posting or pming my details on the dealership?

As for the rear diff oil Subaru offers a Subaru brand rear lsd oil which can be purchased at any dealer; although, I believe Subarugenuineparts.com will have a better price.

[Deuce Cam]

Originally Posted by sujak

manual says every 30,000

I agree that this is roughly a good interval to change the transmission/rear diff. fluid, but where in the manual does it say this? Everyone on this forum says to change the transmission/rear diff fluid at 30K per the manual/Subaru, but the manual doesn't actually state this. Where is this infor coming from? I guess it's possible the 06 manual is different from the 04/05?

Anyway, I checked the maintanence interval schedule in the manual for these fluids and an (I) "inspect" is listed every 30k; no (P) "perform" or (R) "replace" are listed. However, there is a linked note for these fluids which says they should be replaced every 15k if the car is used in extreme driving conditions (hot weather, dusty, etc.)

So basically, according to the manual, it says you don't need to change the transmission/rear diff fluid at all unless the car is driven in extreme conditions , in which case it should be changed every 15k . I think its safe to assume all STIs are driven under "extreme conditions" and I would recommend changing it every 15-20k.

to Subaru for such a vague description in the manual. I actually wrote to SOA and complained, this is the response I received:

"I researched previously with our Technical Services Department as to when these fluids need to be replaced. They advised: The transmission fluid in your Subaru should be replaced if it is really black and smells burnt."

I couldn't believe this response, friggin morons.

[Cr8zyJAP07]

every 30k so im still good.

[jays05]

I changed my tranny + rear diff fluid at 15k miles, then did the tranny again at 30k. Now at ~48k I am changing the tranny + rear diff fluid again. Motul 90pa in the rear diff and Motul 300 + a little Syncromesh in the tranny. A half quart of syncromesh seems to help with my grindy 2nd/5th syncros.

[JuSTin05Impreza]

how would mobil 1 75w90 do in the tranny and rear diff?

[XxSCAxX]

^ it should.

i put valvoline 80w-90 in my tranny and diff two days ago. i wanted the 75w-90 but the local store was out and i didnt feel like ordering some.

to help ya out the rear diff takes 1 qt, and the tranny takes 4.3.

[Turninconcepts.com]

Originally Posted by JuSTin05Impreza

how would mobil 1 75w90 do in the tranny and rear diff?

We tried the MObil 1 in the trans and hated it. Shifts were much more notchy than before and grinding eventually became common.

We are partial to the Gear 300, but are working on a project to get Subaru Extra S to people.

Tony