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>>Tranny Fluid Info and Experimenting Thread<< (Amsoil, Redline, USC, etc.)

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#1 · (Edited by Moderator)
>>Tranny Fluid Info and Experimenting Thread<< (Amsoil, Redline, USC, etc.)

UPDATE:

To start off, a link to " MEMBER TESTIMONIALS (on page 2 of this thread)" where there are tons of testimonials and lots to read.

What I ended up running and install pics. >>>>HERE on page 4<<<<


MY Blackstone analysis of my USC fluid that I replaced. >>>HERE<<<

Also started a "What fluid was your car running when it blew?" thread.

One more link to the Uncle Scotty's Cocktail Thread on Nasioc.

With that said where I started at 1-30-08:

So it is once again tranny fluid time in my car, or getting close anyways. Last time I used a synthetic version of USC or "Uncle Scottys Cocktail" I came up with. It works great, but in my quest to not leave well enough alone and brand homogeneity, I wanna try an all Amsoil formulation. Specifically, replace the Frankenstein colored Redline Lightweight shockproof with something, but we'll see where the research and findings take me.

What I am currently running:
I mixed up a batch of "Uncle Scottys Cocktail" but a full synthetic version in my 06 TR at 15k miles.

1 qt Redline lightweight shockproof
1 qt Amsoil syncromesh
2 qt Amsoil 75w90 gear oil.
What I am thinking about going with:

4 0z Amsoil slip lock
1
qt Amsoil MTG
1 qt Amsoil syncromesh
1.5 qt Amsoil 75w90 gear oil.

The bold is what I am thinking about to replace the Lightweight shockproof. They have a lower kinematic viscosity at 40 deg which should lead to improved shift at cold temps. Using all Amsoil products also guarantees (through Amsoil) that I can up the service interval considerably.



Discuss.

Here are the results:

Now at page 24 we have come to some conclusions:

* We've decided Uncle Scotty's cocktail shifts nice for a while but breaks down really fast and needs really short change intervals.
--Also don't think syncromesh needs to be in the blend
--There is also concern it may cause extra wear

* Redline Lightweight Shockproof works well in the 5MT but not the STI trans (slinger lubrication versus pump)
--Seems to work just as well straight as mixed

* Straight Severe Gear 75w90 from Amsoil is not good in cold weather, but works well when mixed with shockproof

* SD_GR still loves his Valvoline conventional 75w90

* Subaru Extra S is the greatest gear oil to put in a stock Subaru
--It works well for a long time, shifts great, but is not sold in the quart. Its sold in the 5 gal drum, but many Subi tuners and dealer have it

FWIW Redline 75w90NS is what you'd run in the 5MT, but in non-mixed form it hasn't netted near the result of the Extra-S. Don't use MT90.
 
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#2 ·
This is interesting. I don't know much about the demands of a gearbox on lubes, but it seems the wear items will be mainly the syncros and gears themselves (let's leave any other components aside unless someone sees a disaster coming). You should be able to tell how the syncros like it just by shifting.

Assuming you go for it, you'd have no way to know the effect on the gears themselves unless you stuck with it and looked for bits or sent off a sample (I don't know if Blackstone does gear lube analysis). Plus, what's a "normal" sludge after a gear oil change vs. an abnormal sludge due to increased wear? I don't know.

Given all that, if you do try it, my advice is to pay attention to shifting and also to whine, and either way I'd actually not listen to Amsoil, I'd keep shorter intervals than they recommend just to be safe.

Amsoil are good with questions. Have you considered using whatever product combination they recommend instead of the Uncle's mix with substitutes?

BTW, how may miles on the previous full-synth cocktail?
 
#3 · (Edited)
I have not contacted Amsoil, but now that you mention it I think I will, although I fear I will get an android on the phone who replies with only "Use 75w90 Severe Gear." Hopefully i can talk to a lubrication engineer.

I have just over 17k miles on the previous cocktail, and while the "color " seems to be fine, based on "Uncle Scotty's" recommendations and my own OCD habit of shorter maintenance intervals, I'm considering a routine fluid swap.

The transmission has loved the old concoction and still shifts more smoothly than stock.

My main reasons for wanting to stray from the USC:

1. is for research for Subi members benefit (buying all ingrediants from one MFG is a lot easier, as currently you need to hunt all over town to find them)

2. Possibly further improve on the cocktail.

3. Help dispel the "glass tranny" rumor by making mine live at elevated power levels.

4. Get rid of the dead warranty voiding giveaway of the Frankenstein blue fluid color.

5. Further improve shifting/reduce whine at start up temps over USC. (Redline Lightweight shockproof has a kinematic viscosity similar to 75w140.)
 
#4 · (Edited)
I spoke with a lubrication engineer over at Amsoil after getting the typical drone canned corporate response from the technician. The Engineer was very knowledgeable and helpful. He had concerns about mixing different fluids, even those within their catalog. After explaining the USC cocktail to him and my take on it and its performance, he explained that a 20k-30k mile service interval would be recommended for it maximum. The reason being is that specifically the Syncromesh fluid (5w30) is Engine oil based as are its additives and they conflict with the SVG 75w90 additives and cause them to degrade quicker. After explaining to him the above results I wanted to achieve, we came up with a formulation that he believes will be very effective and its simple.

3 qts MTG 75w 90 gear oil
8 oz Amsoil slip lock

The MTG has the same high heat protection as the SVG 75w90, but has less friction additives so requires more slip lock. The MTG is also 30% thinner than the SVG in cold weather despite their similar rating.

He also urged I test the USC (have it analyzed) for Science sake. Both Amsoil and Blackstone labs offer testing services for a fee.

Amsoil kit/testing fee is $26. Blackstones fee is $22.50.

Blackstone it is.

Before I swap the fluid I believe I will give Redline a call and see what their take on the situation is.
 
#6 · (Edited)
He had concerns about mixing different fluids, even those within their catalog.
Not surprising. Many gearbox makers warn against mixing, including Subaru in my 02 user's manual.

After explaining the USC cocktail to him and my take on it and its performance, he explained that a 20k-30k mile service interval would be recommended for it minimum.
Do you mean maximum -- as in, don't let it go past 20K or 30K? That'd match what Uncle posted at one point too. Very interesting!

I'm heading over to Amsoil's site to look at their verbage. Nice detective work there, great info you've uncovered!

EDIT: I see the MTG is listed as GL4 and MT-1. I thought MT-1 was a GL5 that's safe for yellow metals in manual transmissions (hence the MT). I did not know a GL4 could be MT-1. Did he mention whether it's GL5? (I'm assuming he knew you "need" a GL5).
 
#7 · (Edited)
My car came with Dino 75w 90 and shifted mediocre at best. Other than my worry of mixing, I have nothing but great things to say about the USC.

Do you mean maximum -- as in, don't let it go past 20K or 30K? That'd match what Uncle posted at one point too. Very interesting!
Yes no more than 20k-30k miles. Of which I am getting close to 20k miles.

EDIT: I see the MTG is listed as GL4 and MT-1. I thought MT-1 was a GL5 that's safe for yellow metals in manual transmissions (hence the MT). I did not know a GL4 could be MT-1. Did he mention whether it's GL5? (I'm assuming he knew you "need" a GL5).
Yes he said even though its rated at a GL4 it technically could be a GL5 but for some reason (maybe time of release) has not been upgraded to a GL5 rating, and he elaborated on rating scales and further explained why it met Gl5 of which I can't remember off hand. But yes I told him it needed GL5 and he also knew from experience (he was a gearhead too and spoke of his Factory 5 MK3 Cobra kit car) and assured me it was the right stuff.
 
#9 · (Edited)
Swapover table

Amsoil = Redline = Mobil1 = Valvoline = Royal Purple

MTG 75w90 = 75w90NS

SVG 75w90 = 75w90 = LS75w90 = Synpower 75w90 = Max Gear

Slip Lock = Limited slip friction modifier



I still dunno what Redline Lightweight Shockproof = ? And without fluid property listings similar to amsoil, its hard to find out. It appears from what little literature they have available that it performs slightly better than their 75w90 under normal circumstances but really outperforms it in a shock load situation. * see pdf on redlines website for graph. Edit: on page 2 of the PDF it shows Lightweight shockproof as being GL5

Edit: After extensive web testimonials (Nasioc, Forrester forums, random DSM sites) it appears most people rave about running solely the lightweight shockproof in the Subaru 5MT. The Redline website seems to be rather vague or with holding on applications or crossovers for the Shockproof. I see no OEM or API ratings listed anywhere.

Verbage that intrigues me
From redlineoil.com:

ShockProof® products work in a variety of differential and transmissions...-these fluids are designed wet sump or splash type lubrication.

A unique gear oil designed to lubricate racing transmissions and transaxles which see serious loads (not recommended for most syncro-type transmissions). It has excellent low-temperature flow which allows easier shifting when cold.

Red Line Synthetic ShockProof™ Gear Oil provides
unequalled protection for high-performance differentials
and transmissions which are heavily loaded or which see
shock-loading.

Red Line ShockProof™ can be
used in conventional, limited-slip, or locker differentials.
Red Line ShockProof™ is designed for use in
competition differentials and transmissions.
I shall call Redline tomorrow and get their advice.
 
#13 ·
Edit: After extensive web testimonials (Nasioc, Forrester forums, random DSM sites) it appears most people rave about running solely the lightweight shockproof in the Subaru 5MT. The Redline website seems to be rather vague or with holding on applications or crossovers for the Shockproof. I see no OEM or API raings listed anywhere.
I've seen talk of this too. What's made me hesitate is that some of the recommendations come from rallyists, and their needs are quite different than road car drivers. I've also seen mention of 50:50 lightweight shockproof and 75W90 (NS, I believe). The mixture seems more reasonable to me but there's no rational reason for it, just a feeling.
 
#10 ·
so which one are you using right now ?

1 qt Redline lightweight shockproof
1 qt Amsoil syncromesh
2 qt Amsoil 75w90 gear oil.

or

4 0z Amsoil slip lock
1 qt Amsoil MTG
1 qt Amsoil syncromesh
1.5 qt Amsoil 75w90 gear oil.
 
#16 ·
I'll share my experience w/ gear oil. I've owned a WRX since 2001 (a 2002 sedan and currently a 2004 wagon). Very quickly into my first car I swapped in M1 synthetic in both the tranny/rear lsd. At first it was lovely and I patted myself on the back. Not too shortly afterward I was headed to Portland for a driving school at PIR. When we arrived in Portland (1200 miles later) I was having SERIOUS trouble downshifting. With the driving school the next day I knew I was in trouble. I had read some anecdotal evidence of Shockproof working, found a race shop and bought some lightweight Shockproof (got some funny looks in the motel parking lot w/ my car up on ramps and me in my coveralls :)). Took it for a spin- butter. Track day when great, downshifting like a dream. Ran Shockproof w/ very good success until I sold the sedan and bought the wagon.

I knew w/ the wagon M1 was not an option (and found lots and lots of evidence w/ other syns that folks weren't having good luck either). I thought about going Shockproof again, but w/ a brand new car (and it's Hulk green color-shockproof not my car :)) that Shockproof would not be warranty friendly. The oe gear oil was mediocre as far as downshifting, as the weeks went by I knew I needed to swap it out. I stumbled onto Subaru Extra S (listening to the likes of Gary Sheehan of USTCC fame)- it's a dino oil, 75W90, Subaru labeled (lots of Japanese writing) and only available in 5 gallon (actually 20 liters) pails unfortunately. My experience has been very positive w/ this fluid, this is w/ dozens of arduous track days (and lots and lots of autoxing). It's nice to know that there is something that works and very warranty friendly.

https://www.subarugenuineparts.com/product_info.php?cPath=33_92&products_id=1073
 
#18 ·
lightweight (not super lightweight)

I've had several guys pm me about selling them some extra S (I haven't because it's a pain and will likely end up using it all), me thinks if you happened to have left over you could easily get rid of it. Might check your local forums, maybe a couple of local guys could go in on it together????
 
#19 ·
Do you happen to recall how long (miles or time) you kept the lightweight shockproof in the 02 gearbox with good results in donwshifting? I know you tend to change fluids more frequently than I do since your use pattern is heavier but it'd help gauge how long the good feel is maintained with the shockproof.
 
#20 ·
someone in the other thread asked me about longevity on the extra S and can't really answer that or your question either. I got in the habit of swapping out gear oil every spring (roughly 12-15k miles)- so it lasts at least that long :)
 
#21 · (Edited)
Redline

Just got off the phone with the Redline lubrication engineer and his recommendations seem counterintuitive at best and conflicting with the info received from Amsoil.

The Redline lubrication Engineer recommends straight 75w90NS (equivalent to Amsoil MTG) with no additives or friction modifiers. He explained that in order to have proper smooth syncro operation you must not use a friction modifier as they are "too slippery" and the syncros "need friction" to work. He explained that the 75w90 (Amsoil SVG 75w90) has too high a modifier content and will cause notchy shifting and propagate the Wrx shifting issue.

On Redline Shockproof:

Despite Web testimonials, the lubrication engineer said they didn't recommend the Shockproof in the Impreza for a number of reasons.

1. Not GL5 rated--(listed as GL5 in .pdf on page 1)
2. Freak Blue color (no joke he actually said this)
3. Too high of a friction modifier content, too slippery for proper syncro operation.
4. Worse cold flow characteristics than the 75w90NS.

To me it seems his recommendations go against even my real world experience.

I expected to get off the phone with a definite and confident direction when in reality it had the opposite effect. Frankly I felt like :bill: :confused:
 
#22 · (Edited)
More Research:

Analyzing the websites:

Amsoil:

From:
https://www.amsoil.com/storefront/svg.aspx

MTG

MTG excels in hot and cold temperature extremes that exceed the limits of conventional mineral oils. It protects against rust, keeps seals soft for long life, and is compatible with brass synchros for smooth synchromesh shift quality.
SVG

AMSOIL SEVERE GEAR® is compatible with most limited slip differentials. If limited slip differential chatter occurs, add AMSOIL Slip-Lock™ friction modifier additive.
Recommended for use in differentials, manual transmissions and other gear applications requiring any of the following specifications: API GL-5, MT-1,

Applications
AMSOIL SEVERE GEAR® Synthetic EP Lubricants are excellent for severe applications, such as towing, hauling, steep hill driving, commercial use, plowing, racing, off-road use, rapid acceleration, frequent stop-and-go operation and high ambient temperatures.
Higher horsepower, towing and hauling capabilities of modern vehicles make turbo diesel pick-ups, SUVs, vans and delivery/utility vehicles especially prone to severe service. Other severe duty vehicles include light, medium and heavy-duty trucks, buses, heavy equipment, 4X4s, tow trucks, race cars, tractors, and motorhomes.
For product service life in differentials, consult your owner’s manual or the Original Equipment Manufacturer (OEM) to establish the application, NORMAL or SEVERE.

Redline:

From: http://www.redlineoil.com/products_gearlubricants.asp

75w90

Our most popular gear oil, this is the preferred product in nearly all car and light truck differentials, both conventional and limited-slip. 75W90 is preferred for most racing applications. It contains friction modifier which is recommended for limited-slip units. 75W90 Gear Oil can be used in many transmissions and transaxles; however, other Red Line lubricants have better frictional properties for rapid synchronization. Exceeds API GL-5.
75w90NS
This GL-5-type geal oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin.


Lightweight shockproof


ShockProof® products work in a variety of differential and transmissions...-these fluids are designed wet sump or splash type lubrication.

A unique gear oil designed to lubricate racing transmissions and transaxles which see serious loads (not recommended for most syncro-type transmissions). It has excellent low-temperature flow which allows easier shifting when cold.

Red Line Synthetic ShockProof™ Gear Oil provides
unequalled protection for high-performance differentials
and transmissions which are heavily loaded or which see
shock-loading.

Red Line ShockProof™ can be
used in conventional, limited-slip, or locker differentials.
Red Line ShockProof™ is designed for use in
competition differentials and transmissions.

Seems to support Redline engineers recommendations.

MOBIL1:

from: http://www.mobiloil.com/USA-English...bil_1_Fully_Synthetic_Gear_Lube_75W-90LS.aspx

LS 75w90

Mobil 1® Synthetic Gear Lube LS 75W-90 is a supreme performance, synthetic, multi-purpose, SAE 75W-90 automotive gear lubricant designed to meet the highest level of performance requirements of modern passenger vehicles in all types of operating conditions, including limited slip applications, as well as delivering outstanding power transfer performance.

Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required. For axles requiring the highest level of limited-slip performance, OEM specific LS additives can be added to this fluid.
VALVOLINE:

from:http://www.valvoline.com/pages/products/product_detail.asp?product=58

Synpower 75w90

Valvoline SynPower Gear Oil is a full synthetic, thermally stable, extreme-pressure gear lubricant designed to operate and protect in both high and low extreme-temperature conditions. SynPower Gear Oil is specially recommended for limited-slip hypoid differentials.
  • Contains additives to assist in protecting gear teeth
  • Maintains excellent low temperature fluid protection down to -50°F (-46°C)
  • Provides outstanding thermal stability for cleanliness and longer service life
  • Contains special additives to reduce chattering in limited-slip differentials
  • Recommended for (conventional and limited slip) manual transmissions where an API GL-5 or MT-1 fluid is specified
  • Protects parts from rust and corrosion
  • Compatible with conventional gear lubricants
Royal Purple

from: http://www.royalpurple.com/gear-oil.html

Maxgear


Max-Gear is an ultra-tough automotive gear oil. It’s designed to maximize power and provide unsurpassed protection to heavily loaded gears. It makes gears run smoother, quieter, cooler and longer without overhauls.
Max-Gear outperforms other gear oils because it combines the highest quality synthetic oils with Royal Purple’s proprietary Synslide additive technology.
Max-Gear is recommended for use in truck, motor home / RV, and automotive front or rear differentials, manual transmissions, and lower gear units of marine engines that specify use of an API GL-5 or GL-4 fluid. All viscosities of Max-Gear are formulated with hypoid friction modifiers necessary for use in clutch or cone type differentials. No additional additives are necessary.
 
#23 ·
I read the first page and think ok Shockproof Lightweight should be perfect for my tranny, with my light duty driving. I get to second page and Redline says not for me:confused1....

I dont care about color:confused: I have no warranty. I just want something that shifts well and is not only available by the barrel.

This thread is great though Jeremy the results should be quite helpfull

i am still:confused1:confused1
 
#25 · (Edited)
Well the results of this thread are still pending more research. I happily endorse USC currently (listed in first post), but am researching all other options.

Member Testimonials are listed in the link in the first post of this thread.

Redline recommends straight 3.8 qts of 75w90NS.
Amsoil recommends MTG with sliplock additive or straight SVG.

If you switch before I do and try either of the above, please post results. Currently, I am undecided which route to go (stay USC, Amsoil or Redline)

I'm thinking of getting a 5 gallon bucket of the Extra S if someone is interested in going partners or buying a gallon off me let me know.

Where are you located?
 
#24 · (Edited by Moderator)
I was asking more on longevity of the transmission with the Extra S... Someone mentioned that the snychromesh eats away at the wrx's tranny, so I'm looking for something to help with good shifting and good for the tranny...

thanks.

I'm thinking of getting a 5 gallon bucket of the Extra S if someone is interested in going partners or buying a gallon off me let me know.

I'm in PA
 
#27 · (Edited)
Analyzing Syncromesh Fluid

Lets Compare Syncromesh fluid to see if their are noticeable difference between them as they are an ingredient in the USC.

Pennzoil

Pennzoil® Synchromesh Fluid
Pennzoil® Synchromesh Fluid is a synchromesh transmission fluid designed for certain manual transaxles and manual transmissions used by General Motors or Chrysler. Pennzoil® Synchromesh Fluid is formulated with high quality paraffinic base stocks, a fluidity modifier, multifunctional performance additives, corrosion inhibitors, a foam suppressor and a shear stable viscosity index improver additive. It provides excellent oxidation stability, low temperature performance, excellent synchronizer performance and compatibility with yellow metals, such as bronze, brass and copper components found in manual transaxles and transmissions. This product will satisfactorily lubricate General Motors or Chrysler manual transaxles and transmissions from -40°C to +150°C.
Benefits:
  • Exhibits excellent low temperature performance
  • Meets GM Specification 9985648 and Chrylser Specification MS-9224
  • Suitable for use in GM manual transaxles and transmissions requiring GM Part No. 12345349 or 12345577
  • Suitable for use in Chrylser transaxles and transmissions requiring Part No. 4874464
  • Excellent synchronizer performance
  • Excellent yellow metal compatibility
Amsoil

Synthetic Manual Synchromesh
Transmission Fluid (MTF)
SAE 5W-30



PRODUCT DESCRIPTION
AMSOIL Synthetic Synchromesh Transmission Fluid (MTF) is a premium quality synthetic lubricant designed to surpass the most demanding lubrication requirements of manual transmissions and transaxles where non-extreme pressure fluids are used.
It protects against rust, keeps seals soft for long life, and is compatible with brass synchros for smooth synchromesh shift quality.
 
#28 · (Edited)
Testimonials for products in this thread

A running tally for reviews of different combinations of NON-OE tranny fluid:

(link to: "+ review" = positive review, "- review" = bad review, "= review" = neutral)


Amsoil:
+ review + review
- review

USC:
+ review + review + review + review + review + review + review + review + review + review + review + review + review

Redline Gear oil only:
- review - review - review - review - review - review - review
= review

MT90
+ review + review + review
- review

Redline shockproof:
+ review + review + review + review + review + review + review + review + review + review

Redline shockproof + gear oil:
+ review + review + review + review + review + review + review

Royal Purple:
+ review

Mobil 1:
+ review
= review
- review - review - review - review - review - review

Syncromesh straight:
+ review + review + review + review
- review

Syncromesh + gear oil:

+ review + review + review + review + review + review + review + review

Subaru Extra S:
+ review + review + review
 
#29 ·
To add to this I have over 10k on my Redline mixture and it is still as wonderful as the day I put it in. I have absolutely zero intention of switching to something else as IMO there is simply no need. The transmission just works exactly as it should.

I also intend on running a few SCCA ProSolo events this year and having the Shockproof in the trans should be helpful for the standing starts.
 
#85 ·
Redline Mix question



I was thinking of trying the redline mix in my 04 WRX. I have been using USC for about 10K with the synchromesh and Hypoy and its much better than the stock oil but am worried about people now saying the Synchromesh might not be a good longterm fluid to use in the tranny.

I live in Boston so we get frequent cold temperatures in the winter here. Using a mix of 2Q's LW Shockproof and 1.5/1.7Q's Redline 75W90NS would I need to add any slip lock for the cold weather?

Is one better than the other also of the Amsoil MTG vs the Redline 75w90NS?

Thanks for any help.
 
#30 · (Edited by Moderator)
what mixture of redline and shock proof do you have?

has any one tried Royal Purple's Synchromax? I"m thinking to drop a court of the royal purple I have and put in some Synchromax... supposed to be good on soft metals found in snycho trannys

looks to be somewhat promising... I think I'll try it and see how it works out...

http://www.royalpurple.com/manual-transmission-fluid.html
 
#31 · (Edited)
what mixture of redline and shock proof do you have?
JR is using 1.7qts of Shockproof and 2 qts Redline 75w90NS

has any one tried Royal Purple's Synchromax? I"m thinking to drop a court of the royal purple I have and put in some Synchromax... supposed to be good on soft metals found in snycho trannys
The only info I have found on here (I have searched a ton) is on the RP maxgear.

I suggest you go for it and report back. Then I'll add it to the review list on page 2.
 
#32 ·
Can I complicate this a little more and ask what difference if any would this stuff have in the six speed?
 
#33 · (Edited)
The 6MT tends to have fewer problems due to its oiling system being an internal pump instead of splash lubrication like the 5MT. But I can say that Redline shockproof is not recommended in the STi 6MT as it may clog the internal pump. This info is on redlines website and I believe page 1 of this thread.


ShockProof® products work in a variety of differential and transmissions, however, should not be used with pumps, filters, and with small lines--these fluids are designed wet sump or splash type lubrication.
http://www.redlineoil.com/products_gearlubricants.asp?productID=43&subCategoryID=16&categoryID=6

Based on all my research, I would recommend a 75w90 with an additive in it for the 6MT. I would probably run the Amsoil SVG 75w90 with 4oz of Slip lock to help out the front LSD. Or perhaps a syncromesh blend.
 
#34 ·
Lots of great info here. I was one of the '+ reviews' for straight Redline Shockproof Lightweight over 2 yrs ago. Guess what I'm still running it.:thumbup: >100k miles on the stock tranny/engine @ >350whp/340wtq.:thumbup:
 
#41 ·
Great Article on the STi 6MT

http://www.driveperformance.subaru.com/version1_1/blueprint.asp

Interesting:

The gear set is mounted to a steel adaptor plate, which is bolted to the front of the differential casing. The transmission casing supports the gear set at the rear. This straightforward design adds to strength and durability.
To withstand the engine’s 300 lb-ft of torque, transmission gears require added hardening of their surfaces. Hardening the interior metal would make the gears fragile and susceptible to breakage, so the hardening process is applied only to the gear surfaces.
Subaru uses two processes to harden the gear teeth a carburizing heat treatment and quenching process, and a shot-peening process. Carburizing the steel gears involves exposing them to heat and carbon to form surfaces that are then hardened by quenching in a liquid. Shot peening bombards the surfaces of the gears with small metal pieces at high velocity, which is similar in concept to a blacksmith hammering steel into shape.
But remember, unlike a traditional two-wheel-drive vehicle where wheelspin is a common occurrence, Subaru All-Wheel Drive provides rock-solid traction. This same resistance to wheelspin can put a tremendous strain on a transmission gear set. The choice is yours. Drag racing any vehicle exposes a drivetrain to forces well beyond those of normal day-to-day driving. These types of failures are not a consideration of any manufacturer’s warranty. Sorry.

OILED AND PUMPED


The 6-speed transmission is lubricated by a trochoidal oil pump mounted at the rear of the unit. The pump has a 4-lobe inner rotor and 5-lobe outer rotor. Gear-driven by the center differential, the rotors force oil to the transmission’s main shaft, pinion shaft and transfer gears at a rate that depends on the center differential’s speed. A regulator and pressure-relief valve maintain oil pressure.
A pressurized system ensures a constant oil supply to the gearing while minimizing the amount of oil required within the transmission case. The oil level lies underneath most of the gearing, which reduces both friction and oil foaming. Reduced friction improves efficiency and performance, and keeping the oil from foaming helps to maintain oil quality and effectiveness.
While lubricating the transmission, the oil system also helps to cool it by carrying away heat from the gearing, which enhances durability and reliability.
 
#42 · (Edited)
Independant oil study

Found a Very Very informative write up on oils.

Interesting to this thread:

Both Redline 75w90 and Royal Purple Max Gear failed the Brookfield Viscosity@ -40°C (-40°F) for 75W-90.

Royal Purple and Lucas failed the cold-temperature Brookfield requirements for 75W gear
lubes, as well as the high-temperature requirements for SAE 90 gear lubes, effectively disqualifying them entirely from the
SAE 75W-90 category. Royal Purple Max-Gear, having also failed the Shear Stability Test, was the only gear lube to fail
every parameter of the SAE J306 requirements. Red Line was 14,100 cP over the maximum allowable viscosity at 164,100
cP,
http://www.syntheticwarehouse.com/brochures/g2457_gearlube_study.pdf

Posted conclusions, and the lowest score wins. Black denotes not failing any category. FYI: Castrol Hypoy C 80w90 is gear oil "Uncle Scotty on Nasioc" recommends for his USC.
 
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