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Trans/Dif Oil Change and Issues


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Hello all. I have a 2006 LEgacy GT, manual trans. 5 speed. Have had it since 2008 with 20k miles, now have 180k miles. I havent done any work on it but recently got a Miata and started working on that so I have some confidence.


In the last month or so, the shifting has gotten really notchy and difficult, sometimes having to really push it into gear. Thought I would start with trans/dif fluid changes.


So question would be:

1. should that help my shifting issues?

2. What fluid (Redline, etc) have yall recommend

3. Anyone else have similar mileage and experience the same issues.




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Cold weather brings out the worst in old lubricants. Even though the fluid does not get dirty like engine oil, additives eventually wear out and bits of metal will be in it from normal wear and tear.


You should be changing your manual trans oil and rear diff oil more frequently, suggest 30K miles, some people stretch that out a bit.


Try Motul Gear 300 in the manual trans. Rear diff is less sensitive, any good synthetic 75W90 GL-5 gear oil will work OK. You can use Motul 300 there, also, though it is a bit expensive.

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  • 2 weeks later...
Warm weather brought out the initiative in me so I went to change the manual transmission fluid. A couple years ago I bought a case of Subaru Certified Performance 75W90 Gear Oil. Drawing the old fluid was no problem but the refill was. I have a funnel with a long flexible hose and a fine screen at the base of the funnel to trap any solid contaminants. The flow of the oil was slow to start with, and got slower and slower. When the funnel finally emptied, I noticed the screen was clogged with an orange colored grit which must have precipitated out of the fluid. You could also see traces of the grit on the bottom of the empty bottles. Has anyone else had this issue (fyi, the oil was stored in the basement where temperatures typically run around 60-75 degrees)? I doubt this stuff is harmful, but I'm going back to Redline NS next time around.
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I now only use Motul 300 gear. I've spent to much money on rebuilding tranny's to use anything else.


OP are you still around ?


The real Extra-S is no longer made, that is the only other fluid I would use, but I used up my 5 gallon can.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.


Engine Build - Click Here

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Between supertech, subaru extra-s, amsoil severe gear, and red line, red line 75w-90 NS is my favorite in the gearbox.


My mistake assuming the newer Subaru gear oil would be at least as good as extra-s. I had used Red Line in the past and was very happy with it. Seems like the transmission was quieter too.

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