Transmission Fluid for 04 STi

chaddeus · 07-17-2006, 10:22 PM

I had been reading a lot regarding the transmission fluid for the STi. The Uncle Scotty's mixture is somehow confusing.

It seems that people are happy with it are not driving STi and there are some post that says the the Redline LightWeight Shockproof is not suitable for Sycros Manual Transmission.

"Samurai Jack" from NASIOC said

In a non-STigearbox, the gear oil splashes around to lubricate the gears.

In an STi gearbox, the gear oil is pumped around to lubricate the gears.

Redline's concern is that, due to the properties of Shockproof to ahdere to metal, the shockproof may actually either reduce the size of, or completely block, the tubing that the gear lube is being pumped through.

So what fluid is recommended for the STi?

- Charles

Xman · 07-18-2006, 08:07 AM

Most people experiment with semi or full synthetics and many end up back with plain old "Subaru" brand oil sourced from a dealer. I've never heard of issues with this plain Jane oil but it's not very "sexy".

If you have a particular application you are using the car for (rally, rallyX, autoX, trackdays, etc) more specific info might be easier to offer.

jph · 07-18-2006, 08:56 AM

after doing a lot of reading, i decided to go with "Motul Gear 300"
so far, i'm pretty damn pleased with it

J.

WolfPlayer · 07-18-2006, 11:09 AM

Motul Gear 300 here also. So far so good.

t

Mykl · 07-18-2006, 11:43 AM

I don't see anything wrong with OEM, so that's what I'm going to stick to. If it works, why change it?

WolfPlayer · 07-18-2006, 12:02 PM

Quote:

Originally Posted by Mykl

I don't see anything wrong with OEM, so that's what I'm going to stick to. If it works, why change it?

Oh no he didn't! lol j/k

Ummm - why are we all here? Why do we install TBEs? Why do we get Engine Management? Why are we installing harder bushings?

ahhahahahaaha. Mo Powah! Betta Parts! Betta Feel! Etc, etc, etc.

t

Mykl · 07-18-2006, 12:16 PM

Quote:

Originally Posted by WolfPlayer

Oh no he didn't! lol j/k

Ummm - why are we all here? Why do we install TBEs? Why do we get Engine Management? Why are we installing harder bushings?

ahhahahahaaha. Mo Powah! Betta Parts! Betta Feel! Etc, etc, etc.

t

Well, I agree... but this is one of those things that seems better off left alone. Our gearboxes aren't exactly cheap and I'm sure a team of engineers in Japan spent quite a bit of time coming up with the best solution for lubrication.

I'm willing to change something if there's a noticeable or measurable benefit to doing so, but I'm not the type that's going to change something simply for the sake of change.

I also like to have an understanding for why something is the way it is on my car before I change it to something else. I know why Subaru used the exhaust parts and engine management that they did, and I know what I'm doing to the car by changing them. I have no idea why Subaru went with the specific gear oil they did, and I have no idea what it's going to do to the gearbox if I change it.

WolfPlayer · 07-18-2006, 01:05 PM

Quote:

Originally Posted by Mykl

I know why Subaru used the ... engine management that they did

Please do tell.

I mostly agree with what you said. However, let's take this a step further. If you want to stick with stock fluid then you need to buy this ...

https://www.subarugenuineparts.com/p...oducts_id=1073

I don't know of any smaller containers and I don't even know of many people even using this. Shipping will be a bear on this item. Probably looking at $180+. The nice thing is that it should give you about 3-4 oil changes

t

ValvetrainEngineer · 07-19-2006, 07:36 PM

There's many threads on this...but in my experience, first 'upgraded' to Redline...then had tons of gear grinds when shifting. Then went to Valvoline 80w-90 and the grinds went way down, but not away. Now I found Valvoline 75W-90 (same weight as stock) and my tranny is very happy. That's all I would use now...

I would say for engine oil Fuji avoided synthetic to save $, since synthetic is proven many times over to be superior. For tranny...I'd say not necessarily so...

MGizzle · 09-05-2006, 08:16 AM

I heard that Synthetic oil for the STi sucks because our synchros use friction to work properly but with the synthetic it is more slippery and you damage them a lot faster. I don't remeber where I found this forum but ever since I have been trying to stay away from synthetic oil for my tranny.

klaymon · 09-05-2006, 08:23 AM

I used to have Motul 300 in mine and got lots of 3rd gear grinding. Went back to Valvoline 80w-90 (dino) and it went away.

Delaware Subaru · 09-05-2006, 08:39 AM

I use what Andrew@Andrewtech reccomends. 1 qt. Motul and the rest is Redline LW. Works great for me.

kinger · 09-05-2006, 09:18 AM

I used Valvoline dino 75w90 then switched to royal purple max gear and didn't notice any difference. Probably will go back to the dino.

Rear diff I use subaru fluid and valvoline and again noticed no difference but will stay with the subaru specfic stuff now.

**abdi** · 09-05-2006, 01:03 PM

Silkolene or Motul. I would not buy anything else.

I tried Redline back when I bought the car in 03 and I had a horrible experience.

Silkolene has worked as expected in all conditions.

Here is a bit from the Silkolene distributor in the U.S:

"Silktran Syn 5 75W-90 fully synthetic gear oil is a new generation multifunction product designed primarily for use in manual transmissions and final drive units, including road and competition limited-slip differentials. Race proven in sequential gearboxes and active transmissions, Silktran SYN 5 gear oil utilizes the latest and most thermally stable components available and may be used in equipment subjected to the most arduous duties. Components used incorporate the latest chemistry designed to meet the most recently defined and most stringent gear oil performance criteria. Full synthetic base stock gives vastly improved thermal stability compared to mineral oil based products. Improved lubricity gives better load carrying, lower wear rates and reduced power loss compared with conventional gear oils.

* Very wide operating temperature range down to -40 °F.
* May be used with confidence where conventional SAE90, 85W-90 or 80W-90 lubricants are commonly recommended.
* Ensures proper lubrication of highly stressed components even at extremes of temperature.
* Contains no components which can shear down in use and therefore can be described as a true stay-in-grade product.
* Lower viscosity than conventional gear oils gives potential for fuel economy.
* Suitable for use in most synchromesh gearboxes and final drives—embraces traditional synchromesh gear oil performance (API GL4) and hypoid axle performance (API GL5) in one product."

Be sure to get SilkTran 5, for the transmission and BOA 90 for the rear diff, while you are at it. This stuff is not cheap.
Motul 300 and 90PA are similar to the Silkolene.

Pick your prefered brand of the two.

Also... You can use the Subaru specific fluids of course.

Edited. To add Subaru specific fluids.

***Neanderthal Racing*** · 09-05-2006, 01:25 PM

motul gear ff competition. in fact, it's about time to change it.

07-17-2006, 10:22 PM	#1
chaddeus STI Driver Car: 04 Subaru WRX STi Location: Milpitas, CA Posts: 227 Join Date: May 2004 Trader Rating: (0)	Transmission Fluid for 04 STi I had been reading a lot regarding the transmission fluid for the STi. The Uncle Scotty's mixture is somehow confusing. It seems that people are happy with it are not driving STi and there are some post that says the the Redline LightWeight Shockproof is not suitable for Sycros Manual Transmission. "Samurai Jack" from NASIOC said In a non-STigearbox, the gear oil splashes around to lubricate the gears. In an STi gearbox, the gear oil is pumped around to lubricate the gears. Redline's concern is that, due to the properties of Shockproof to ahdere to metal, the shockproof may actually either reduce the size of, or completely block, the tubing that the gear lube is being pumped through. So what fluid is recommended for the STi? - Charles This ad is not endorsed by this member. Please register or login to hide this ad.

09-05-2006, 01:03 PM	#14
abdi Gold Member Car: STi sold. F150 & race prepared Z06 now. Location: Western MA Posts: 236 Join Date: Aug 2003 Trader Rating: (3)	Silkolene or Motul. I would not buy anything else. I tried Redline back when I bought the car in 03 and I had a horrible experience. Silkolene has worked as expected in all conditions. Here is a bit from the Silkolene distributor in the U.S: "Silktran Syn 5 75W-90 fully synthetic gear oil is a new generation multifunction product designed primarily for use in manual transmissions and final drive units, including road and competition limited-slip differentials. Race proven in sequential gearboxes and active transmissions, Silktran SYN 5 gear oil utilizes the latest and most thermally stable components available and may be used in equipment subjected to the most arduous duties. Components used incorporate the latest chemistry designed to meet the most recently defined and most stringent gear oil performance criteria. Full synthetic base stock gives vastly improved thermal stability compared to mineral oil based products. Improved lubricity gives better load carrying, lower wear rates and reduced power loss compared with conventional gear oils. * Very wide operating temperature range down to -40 °F. * May be used with confidence where conventional SAE90, 85W-90 or 80W-90 lubricants are commonly recommended. * Ensures proper lubrication of highly stressed components even at extremes of temperature. * Contains no components which can shear down in use and therefore can be described as a true stay-in-grade product. * Lower viscosity than conventional gear oils gives potential for fuel economy. * Suitable for use in most synchromesh gearboxes and final drives—embraces traditional synchromesh gear oil performance (API GL4) and hypoid axle performance (API GL5) in one product." Be sure to get SilkTran 5, for the transmission and BOA 90 for the rear diff, while you are at it. This stuff is not cheap. Motul 300 and 90PA are similar to the Silkolene. Pick your prefered brand of the two. Also... You can use the Subaru specific fluids of course. Edited. To add Subaru specific fluids. Last edited by abdi : 09-05-2006 at 01:07 PM.

09-05-2006, 01:25 PM	#15
*Neanderthal Racing* GT R US Car: CUTN EDG project Fav Mod: $20. mudflaps from auto zone Location: my cave Posts: 5,844 Join Date: Dec 2003 Trader Rating: (1)	motul gear ff competition. in fact, it's about time to change it. This ad is not endorsed by this member. Please register or login to hide this ad.

07-18-2006, 08:07 AM	#2
Xman S204 Racer Car: 2004 STi Fav Mod: Momo fixed back seat, harness bar and Willans 6 point harness Location: Rancho Santa Margarita, C Posts: 2,827 Join Date: Apr 2003 Trader Rating: (3)	Most people experiment with semi or full synthetics and many end up back with plain old "Subaru" brand oil sourced from a dealer. I've never heard of issues with this plain Jane oil but it's not very "sexy". If you have a particular application you are using the car for (rally, rallyX, autoX, trackdays, etc) more specific info might be easier to offer.

07-18-2006, 08:56 AM	#3
jph S204 Racer Car: the wagon Location: San Jose, CA Posts: 2,950 Join Date: Apr 2004 Trader Rating: (9)	after doing a lot of reading, i decided to go with "Motul Gear 300" so far, i'm pretty damn pleased with it J.

07-18-2006, 11:09 AM	#4
WolfPlayer Moderator & ECU Tech Car: 05 CGM STI Fav Mod: mo boostaz Location: Fredneck, MD Posts: 3,703 Join Date: Jun 2004 Trader Rating: (6)	Motul Gear 300 here also. So far so good. t

07-18-2006, 11:43 AM	#5
Mykl S204 Racer Car: '04.5 STi Fav Mod: ZZYZX Location: Montgomery, Al Posts: 2,751 Join Date: Apr 2006 Trader Rating: (0)	I don't see anything wrong with OEM, so that's what I'm going to stick to. If it works, why change it?

07-19-2006, 07:36 PM	#9
ValvetrainEngineer Spec C Club Car: '04 WRB Fav Mod: A working ECU... Location: CT Posts: 1,486 Join Date: May 2003 Trader Rating: (7)	There's many threads on this...but in my experience, first 'upgraded' to Redline...then had tons of gear grinds when shifting. Then went to Valvoline 80w-90 and the grinds went way down, but not away. Now I found Valvoline 75W-90 (same weight as stock) and my tranny is very happy. That's all I would use now... I would say for engine oil Fuji avoided synthetic to save $, since synthetic is proven many times over to be superior. For tranny...I'd say not necessarily so...

09-05-2006, 08:16 AM	#10
MGizzle Professional STI Racer Car: 05 STi OBP Fav Mod: Data Acq System Location: Warren, Michigan Posts: 786 Join Date: Jul 2006 Trader Rating: (1)	I heard that Synthetic oil for the STi sucks because our synchros use friction to work properly but with the synthetic it is more slippery and you damage them a lot faster. I don't remeber where I found this forum but ever since I have been trying to stay away from synthetic oil for my tranny.

09-05-2006, 08:23 AM	#11
klaymon S204 Racer Posts: 3,083 Join Date: Jul 2004 Trader Rating: (1)	I used to have Motul 300 in mine and got lots of 3rd gear grinding. Went back to Valvoline 80w-90 (dino) and it went away.

09-05-2006, 08:39 AM	#12
Delaware Subaru Junior STI Driver Fav Mod: flushing toilets Posts: 170 Join Date: Oct 2005 Trader Rating: (2)	I use what Andrew@Andrewtech reccomends. 1 qt. Motul and the rest is Redline LW. Works great for me.

09-05-2006, 09:18 AM	#13
kinger Professional STI Driver Car: 04 STI Fav Mod: Koni shocks Location: BFE Iowa Posts: 497 Join Date: May 2004 Trader Rating: (1)	I used Valvoline dino 75w90 then switched to royal purple max gear and didn't notice any difference. Probably will go back to the dino. Rear diff I use subaru fluid and valvoline and again noticed no difference but will stay with the subaru specfic stuff now.