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Discussion Starter #1
im tryling to learn as much as possible about my car, and would appreciate if anyone can at least verify (or provide more info) on the following...

based on my research (Google, searches through forums, magazines, etc.), here is what i have found (I have a 2008 WRX STI):
  • Transmission Oil - This would be oil for both the Front and Center Differential, correct? The standard (default) for this would be a 75W-90 rating gear oil?
  • Diffential Oil - This would be a LSD-specific oil, right? And would usually applied to the Rear Differential? An OEM-oil would be good enough?
  • Brake Fluid/Clutch Fluid (??) - I would know the brake fluid, but would like to know if the Clutch Fluid/Oil uses the same oil/fluid as that for the brakes?
Thanks in advanced..!!!
 

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It's usually best to follow the owner's manual for the fluids you mentioned.

1. You want 75w-90. Do some research regarding the brand; unfortunately, you probably won't find a definitive answer regarding the brand.

2. I *think* the 08 has the same rear lsd as the 07 models (torsen diff) which means you use 75w-90 (same as the transmission). A torsen doesn't qualify as a "mechanical lsd" so you don't need the special lsd oil. Check the owner's manual to be sure.

3. Not sure on the grade but the clutch fluid is the same as the brake fluid.

Edit: I checked subaru.com and the 08 does have a torsen diff like the 07. FWIW, I just realized that you have a jdm model which means some parts could be different from the usdm model.
 

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Discussion Starter #3
It's usually best to follow the owner's manual for the fluids you mentioned.

1. You want 75w-90. Do some research regarding the brand; unfortunately, you probably won't find a definitive answer regarding the brand.

2. I *think* the 08 has the same rear lsd as the 07 models (torsen diff) which means you use 75w-90 (same as the transmission). A torsen doesn't qualify as a "mechanical lsd" so you don't need the special lsd oil. Check the owner's manual to be sure.

3. Not sure on the grade but the clutch fluid is the same as the brake fluid.

Edit: I checked subaru.com and the 08 does have a torsen diff like the 07. FWIW, I just realized that you have a jdm model which means some parts could be different from the usdm model.
hi Deuce Cam...

thanks for the reply - yes, i plan on doing more research... i just wanted to iron out some of my confusion before moving forward (and avoiding more uncertainties and confusion)...

as for a JDM and a USDM - yes, i realize that some parts could be different; and would do some due diligence... there is just no english forums on the STI here in Japan, so i have to rely more on the non-Japan based sites...

:D
 

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As far as the USDM 2004 STi for example, mine didn't like the Valvoline 75W-90 gear oil.....so in that case, either go with Motul 300 Gear or Subaru S gear oil.

The front diff in 2004 shares the fluid with the transmission.

Brake fluid, I changed mine to Motul 600 RBF when I switched to StopTech SS lines.

Haven't changed the clutch fluid.
 

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I also use RBF 600 brake fluid, it is great stuff! As far as the tranny goes I would be very careful about aftermarket fluids. There are many posts with horror stories about how aftermarket fluid ruined the tranny.
 

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Discussion Starter #7
thanks for the replies, guys...

i think im going with Motul 300 for the tranny/front and center diff

then with Motul 90PA for the rear diff (though going with the OEM fluid is a lot cheaper)

as for the brake fluid/clutch fluid (ive got issues when too much air bubbles get in due to heat) - im still doing some research
 

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Discussion Starter #8
thanks to all, guys...

had my tranny oil/diff oils changed last night - i used Motul Gear 300 all throughout...

however, specs for the 2008 STI says that 4.1L is required for the tranny/front diffs, and about 1.0L for the rear... im now left with about 0.9L of oil that i wont be using for some time... (T.T)
 
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