I'll try to help. I changed my gearbox fluid a few months ago. At 6,000 miles or so. The drain plug magnet had some serious metal sludge built up on it. I went with regular Motul Motyl Gear. I have about 2,000 miles with this oil and haven't had a problem. It shifts much better after the change.

Anyhow, I followed this existing forum how-to guide. http://www.iwsti.com/forums/how-install/96096-how-changing-6mt-trans-oil.html (very helpful write-up imo)

The whole job only took a few hours. I got some big time satisfaction from doing this job for some reason. Well worth it.

I didn't jack-up my car though. I made 4 cheap and dirty ramps from some new 2''x10'' lumber. With the car up an extra 4'' I had enough room to work under her.

Some small things.

- Warm up the fluid a bit

- IIRC, you will need a #50 Torx to drain the clutch side, Not the 21mm that is shown in the guide

- It should be a 10mm allen for the filler plug shown in the first pic

- The part numbers for teh crush washers are not the same. 2008's use a different size. (I did not write down the new part number)

- Might as well flush some new fluid through while your doing the job

- You will need a long neck funnel, no way around it.

- I kept the IC on

- Gear oil didn't smell as bad as everyone says it does

Pics related...

Hope this clears things up.

 

Thanks for the info. I actually went ahead and tackled the oil change yesterday. I initially thought the plug you have pictured was the fill plug pictured in the manual. But when another member said that fill plug is actually accessed from under the car and is on the left side of the tranny, the picture from the manual made sense. The worst part of it was filling the tranny back up. Spilled quite a bit and it took forever. That and waiting 2 hours for the oil to drain. Well worth it though. Ended up using Motul 300 and it definitely shifts better now.

 

Nice write up except that it suggest using the torque wrench to undo the plugs. You should never use a torque wrench to undo fasteners. Save them for proper tightening. Use a breaker bar or a simple ratchet when undoing fasteners to avoid damaging your torque wrench. If you look at his tools, he's doing it right by using a breaker bar but he's calling it a torque bar. It's not since it has no torque gauge.

 

I'll correct this asap. Thanks for pointing it out.

 

Is there a reason to change the trans. oil so soon?

 

What's the factory recommended time and mileage to change transmission and diff oil?

 

i changed mine after break in

 

since theres no dip stick, how do you measure how much is in? just peer through the hole?

 

should be just like when you do the rear diff, fill it up until it starts coming out the hole you're putting it in. *yay accurate measuring!*

pretty lame i know, i wish they had left the dipstick like on the 04-07s...

 

funny how in the 08MY manual, there are 2 diagrams for a dipstick. Turbo/non turbo engines. But yet on the 08MY there is no dipstick. :S

 

Sorry if I'm missing it and it was mentioned, but how much do you fill the tranny? In the past with my FWD cars you just fill it until it starts coming back out of the fill hole. Does that rule apply here as well?

 

You don't want to keep putting oil in until it comes out of the fill, you'll likely overfill the transmission and it would probably take quite a bit more than the recommended 4.7 quarts to do that (it's not like the rear diff or a box on a fwd car). Read your owner's manual to see how much oil you need; then simply put the amount it specifies in the transmission.

 

huh? never heard this before, its always fill until you pour out of the fill plug. ill check the manual, otherwise if you have some leak you have no way of knowing how much to put in as you basically eliminate any measure.

on top of this i just did my tranny, with the front end tilted up i put in just around 4.5, recommended was 4.3.

___

i changed mine at 5kish, gotta doo rear diff also. breakin period leaves alot of shavings around. i could see metal trail at the very end of the oil and thats with the magnet plug on. if you shift and drive hard, fast, and have shortshifter theres no reason to not have clean fresh oil in the tranny. plus it keeps your shifts f'in butter smooth if u change the oil in ur mazda speed i bet you see some improvement in shifting even though you dont recognize any poor shifting.

FYI: trucking companies (smart ones) also change their diff oils within first 5k miles, extended the life of the diffs by double.

 

I have never change the transmision oil on any of my manual cars... and so far no problems.... my 03 mazdaspeed has 200.000 an no problems.

 

ps you need a T70 for the clutch side drain plug on 08 sti. thats the proper size.
not t50

 

yep, i noticed this too when seeing is the 50 fit when i was under changing the oil.

where do you get the motul oil for tranny and rear dif?

i think the rear dif. actually is supposed to takes different oil than the trans, the trans takes Motul 75w90 GL-5, not sure where to get it though maybe super autobacs or your local shop that sells performance goods. and the rear dif oil get at the dealer, there is a special "STi rear dif oil"

What's the factory recommended time and mileage to change transmission and diff oil?

i think its something like every 15-20K miles. i saw it in the owners manual somewhere a while ago.


well i emailed subaru and asked if we put in a certain amount, or fill it till it over flows and here what they said back...

Thank you for taking the time to contact us. The information that you are seeking is found on page 12-4 in the owner's manual. The quantity of transmission oil for your 6-speed 2008 WRX STI is 4.3 quarts.
Thank you for the opportunity to be of assistance. If you need any future assistance, please let us know.
Sincerely,
John J. Mergen
Subaru of America, Inc.
Customer/Dealer Services Dept.

 

Are you saying you could feel or tell the oil level by sticking your finger in the fill hole after adding the transmission oil?

Please understand that I'm only trying to help prevent the spread of misinformation. If your sure about the method for checking the transmission fluid level on the 08/09's then please post some hard evidence of this. Again I don't know for certain, but I'm extremely doubtful that "add fluid until some poors out" method is correct, especially considering the fill hole's location.

Keep in mind that the fill hole is at the very top of the transmission - if you put oil in until it overflows it would be completely full of fluid (ie it would leave little or no air in the box).

 

ok well you can continue to be uncertain and doubtfull. but every car that hasnt had a dipstick uses this method of filling. same as the rear diff. the fill plug is not at the very top of the transmission, its in the middle, the exact location it needs to be for exact filling when level. if u read before i added 4.5 with my front end in the air, the spec is 4.3 i overfilled by .2 because of the tilt, it isnt gonna make any difference and never has for me before.

for some unknown reason your just guessing and pulling at straws on a car you dont even own that has a different method from your car.

 

Perhaps, but saying it's done like every other car that doesn't have a dipstick is a generalization not based on fact, so your argument is no better than mine. The only difference is I can admit I'm not certain. Your right, I don't own the car, but the transmission in both of our cars are almost the same.

Maybe the fill hole is in a different place on the 08-09 transmission (you said it's in the middle which doesn't tell me much), so where is it exactly? The gd's is under the ic on the passenger side on top of the transmission - I'd bet the 08-09s' is in the same place.

You say you need to fill until it overflows, or stick you finger in the hole to check the level, but you didn't even use this methed yourself so how do you really know? Again, please post some proof that your method is correct if you're so sure - if you're method is noted in the owner's manual or technical service manual I'll believe you.

So, are you going to try and continue to discredit me because of my uncertainty, or are you going to provide some actual proof to your claims?

Edit: The second post in this thread shows the location of the fill hole on the GD (circled in red). I'm assuming it's the same hole on the 08 considering it's circled in the picture. Is that where you added the transmission fluid?

 

where do you get the motul oil for tranny and rear dif?

 

its not noted in the manual, all it says is sti has no method for checking oil level, this is not correct either as the fill plug method is the correct way for checking tranny fluid level. and it does not mean i'm wrong. you jsut seem to have problem with numbers because if you car is level you will fill exactly 4.3 quarts as per specification until **** pours out of the hole. mine was not level but tilted as such i added 4.5 quarts until **** poured out. how difficult is that to comprehend? i didnt need to check the level because i just undid the bolts and drained everything, retightned it refilled 4.5 quarts till **** poured out of the hole, at which point sticking my finger in to see if theres fluid at the bottom of the fill hole is pointless.

again you assume wrong the fill plug is on the side of the transmission not on the top. the image is not correct representation of the gr 08, it is a good image to show what the bolt will generally look like. also the instruction to use a t50 is incorrect because t70 is the correct size, a t50 (i tried a t55 i had) will just spin in place or strip as that bolt is in rather tight from factory.

why do you insist on confusing people who could need real instructions on how to do this on their 08 gr, with pointless **** from what its like on you 06 which clearly doesn't apply to anyone reading this for information on how to do this on an 08. jeez........

 

Severe, please understand that my posts aren't an attack on you, and I'm not saying your wrong. I'm saying it's up to you prove that the transmission oil fill process is now different than on past model sti's. You haven't provided anything tangible (ie, real instructions as you put it) to back up your claim, only 'that's how it's done on other cars.' This is the first thread that anyone has mentioned "fill until the fluid comes out" in regards to the sti transmsmission. Are you really suprised that someone questioned it?

If the 08 transmission fill hole truely isn't the one circled in the second post I guess I believe you. Curious, if that's not it then where is it located in relation to that hole? The GR owner's may need to know that location so they have some "real instructions" to go from.

 

look i understand its not an attack on me. but you weren't giving appropriate info to people then arguing with me when i had just done this... its kinda silly and somewhat aggravating especially since you haven't dont this yourself on an 08 and are basically arguing for the hell of it... ill skim through the service manual for the gr once i have a quick moment and post a pic form there of the fill plug but if you crawl under the car its blatantly obvious to find the only plug half way up the tranny...

requesting proof is kinda funny though because no one that actually posts any kind of how-to, proof is hardly ever attached of anything its just how that person did a certain job.

 

I agree, there's not really a need for me to argue with you, but I thought it was necessary so people have some real info to go on. It would be great if someone could post the technical service manual procedure for the 08 so people will truly know if the process has changed.

How am I not giving appropriate info to people? The first description I gave for changing the transmission oil in this thread wasn't wrong (even if you used the circled plug int the second post for the fill hole); you even said yourself the manual doesn't list a way to check the fluid level. Again, knowone has mentioned there was a different fill hole location on the 08. Hell, there wasn't even a hint that the fill hole location was in a different spot until we started arguing, so this argument may not be so pointless afterall.

I admit that I did base my argument off an assumption - I assumed the fill hole on the 08/09 was in the same place as on past models. But this assumption isn't entirely unfounded because knowone has posted anything to contradict that assumption (until a few mentioned "fill until fluid flows out" in this thread). Even though people did mention the "fill until the fluid flows out" method, it's obvious they also came to that conclusion based on an assumption - all mt cars withough a dipstick 'should' follow the same drain fill rule.

I hope you got your info from the service manual. This whole time you haven't said where you got the info. You only arguments are: you don't even have this car, you aren't good with numbers, your not giving appropriate info, and also criticizing my request for proof. Your just attacking me and doing nothing to support your claims. Why should people believe you if you won't tell us where you sourced the info?

All you've had to do was say, "I found the new fill hole location in the technical service manual for the 08 and the new location is x." It's that simple.

 

^ i didnt, i just unbolted, drained and filled.

to me its really no different than doing a regular oil change. infact id be confused if i had a dipstick... and a fill plug on top of the tranny.

my entire point is that i filled nearly to exact spect using the 'fill till some pours out' method, but overfilled lightly because of the tilt since the front was the only side raised up. its clearly the correct method since if car was level it would be exact to spec.

anyway i found the filler plug on the tranny in the service manual #11:

 

so all 4.** quarts go into number 11? thats basically all ive been searching around for. all this time i thought you put the fluid in through the top plug which is #2 on the diagram.

instead you fill the tranny from underneath the car?

where do you fill the center diff from?

 

Thanks severe! I stand corrected.

 

yes you fill through #11 only bolt mid tranny on driver side, for me it was a pain in the ass because the tubing i had was too short to do it from the top, so i managed from the bottom but it was a royal pita.

basically you need something like this:

snake the tube down below into the fill plug, place something below it to catch overflow oil, and fill from the top. i had the same thing but with a screw on top for a bottle instead of a funnel. the tubing was 2x shorter than what i needed. i think 2-3ft would do it, ill buy 4ft and cut to length next time.

 

so i guess the diy is wrong since you cant replace the center diff fluid. was it like this on all model years or just the 08?

so confused. im a technician, but ive never worked on subarus before and this is my first symmetrical awd car

 

Correct, you should follow the diagram severe posted. The front/center diff and transmission share and use the same bath of oil - ie, when you add oil to the fill hole (#11 in the diagram severe posted) it goes in the transmission AND the front/center diff.

 

What happens if you fill tranny using bolt #2?

 

A better question is on my 04 STi, I had to fill from the top fill hole in the first picture in the OP's picture.

I just did a transmission drain and refill using the "Old style" bolt on the topside, think I caused any issues?

This would be great to know before morning when im suppose to drive the car! haha

 

you're car is different - thats a diagram from the 08, if you have a dipstick you might not have a side filler to begin with. regardless i doubt any issue would arise from either as long as it gets down to the gears

 

I filled from top hole, but used side hole to check level.

Also found out if you use the oil dipstick, the correct fill level for the trans ends up being between full and low, dead center. So you can just pull the top one and use that as a gauge as well. Your pick. Filling is really intended from the top hole I believe. The side hole is more of a level check.

 

i dont have a sti, but i do have an 09 wrx and my transmission comes with a dipstick, i was actually surprised when i first noticed it, i wonder if its something the my08 guys can buy and use.....