[tripod]

Instead of all the back and forth and discussions regarding the advisablility of using Amsoil in the drive train, I went to the source, Amsoil, for a response as to the suitablity of their gear lube in the Subaru, and to lay to rest the constant comments regarding the use of a limited-slip additive.

Their response is reproduce below. The SVG is an appropriate lube WITHOUT additional additives.
<!--StartFragment -->
Thank you for contacting AMSOIL with your concerns.<?xml:namespace prefix = o /><o></o>

In response to your inquiry, our AMSOIL SVG 75W90 is an excellent choice for this application. SVG already contains limited-slip additive so no additional additive is necessary. If one chooses to use the LSD additive however, SVG is compatible and this will not create any problems.<o></o>

Click here for more info ==> https://www.amsoil.com/storefront/svg.aspx <o></o>

Sincerely,<o></o>
Ed Kellerman<o></o>
AMSOIL Technical Advisor

[Blaiser]

glad to see you took the initiative. thanks!

[Majin]

thanks tripod, but i am one of the few that doesn't require additional proof - like you i have seen for myself, and i trust Amsoil products above all the other "wanna-be" synthetics. to me, they all pale in comparison to Amsoil.

my experiences with them alone have turned enough people onto their products to warrant me a special title with Amsoil!

[nandanrp]

EDIT: I had a discussion at length with Majin. I pride myself on making informed decisions, and so far what I've read and discussed with him sounds good. I'll wait to see what kind of results people have after a few thousand miles, hopefully people's experiences are better than Redline fluids!

Majin, your new title: "Guinea Pig GB"

[Majin]

taken from Wikipedia:

API viscosity ratings for gear oils are not directly comparable with those for motor oil, and they are thinner than the figures suggest. For example, many modern gearboxes use a 75W90 gear oil, which is actually of equivalent viscosity to a 10W40 motor oil. Multigrade gear oils are becoming more common; while gear oil does not reach the temperatures of motor oil, it does warm up appreciably as the car is driven, due mostly to shear friction (with a small amount of heat conduction through the bellhousing from the engine block).

Fully synthetic gear oils are also used in many vehicles, and have a greater resistance to shear breakdown than mineral oils. They can improve the shifting performance of "difficult" gearboxes, where the excessive slipperiness of some mineral oils can impede synchromesh action.

[solbergfan]

I really don't give a crap what Amsoil says. I care what Subaru says, and they SPECIFICALLY CALL OUT A 90WT MECHANICAL LSD OIL, NOT A 75w90 GL5 GEAR OIL FOR THE REAR DIFF. If you choose to use the wrong stuff that's your decision, but you shouldn't advise other people to. I think Amsoil is referring to a helical LSD when they responded to your inquiry, not a mechanical LSD that is used on STi's RX8's etc....

I used the Severe Gear in my STi for about 1500 miles until I read the manual where it states to use a specific oil. And I was wondering why it was chattering and locking in tight turns.......

http://206.13.93.15/STi_Stuff/STi_Manual/index.htm Check the service manual. And there was a TSB issued for this also-I will find it for you since you don't believe me.

[tripod]

Originally Posted by solbergfan

I really don't give a crap what Amsoil says. I care what Subaru says, and they SPECIFICALLY CALL OUT A 90WT MECHANICAL LSD OIL, NOT A 75w90 GL5 GEAR OIL FOR THE REAR DIFF.

Gee, I hope you park your car when it gets into the 30's, streight weight 90 is only specced out to a low of 40 degrees F. And by the way, get an updated manual.

[Majin]

Originally Posted by solbergfan

I really don't give a crap what Amsoil says. I care what Subaru says, and they SPECIFICALLY CALL OUT A 90WT MECHANICAL LSD OIL, NOT A 75w90 GL5 GEAR OIL FOR THE REAR DIFF. If you choose to use the wrong stuff that's your decision, but you shouldn't advise other people to. I think Amsoil is referring to a helical LSD when they responded to your inquiry, not a mechanical LSD that is used on STi's RX8's etc....

I used the Severe Gear in my STi for about 1500 miles until I read the manual where it states to use a specific oil. And I was wondering why it was chattering and locking in tight turns.......

http://206.13.93.15/STi_Stuff/STi_Manual/index.htm Check the service manual. And there was a TSB issued for this also-I will find it for you since you don't believe me.

it looks like you are getting too excited over this. relax. depending on which Subaru you talk to, you get different answers. my Subaru dealership told me not to bother with the junk they offered there. they told me it was just some bulk crap they purchased in drums and for me to go with a reputable synthetic diff oil. in the other thread, you said to go with the Subaru OEM diff oil because we don't need an LSD additive. evidently, the Subaru OEM stuff is a synthetic fluid that needs an additive.

adapted from andys_911's post:

after looking in the 04 service manual (on page DI-2):

Rear differential gear oil GL-5 (For mechanical LSD)

then there's a chart of weights vs. operating temperature under the title "Rear differential gear oil, Recommended oil"

the chart shows:

90 W is for temperatures over 23° F
85 W is for temperatures over -15° F
80 W is for temperatures under 77° F
75W-90 is good for all temperatures

the "differential gear oil" section (page DI-19) of the shop manual specifies:

Recommended oil:
STi model:
GEAR OIL LSD (Part No. K0904AA080) or equivalent

Oil capacity:
STi model:
0.9 — 1.1 2(1.0 — 1.2 US qt, 0.8 — 1.0 Imp qt)

75W-90 that meets the API GL-5 specification would be the best bet... the 90W is too thick for any place with a winter

since Subaru's fluid is synthetic with additives (which most dealerships don't stock and are not putting into our STis - and most people think that conventional gear oil is required) and a weight designated safe down to only 23°F, i would rather not risk putting the stock crap in the rear diff when i can obviously put a superior fluid in my car like i do with the engine oil. as i see it, Subaru does not specify synthetic motor oil, but just about everyone on this site uses it.

entertain yourself with read the following thread from Boxer (before your time here on IWSTi): Need rear diff. oil? Have a look.

i don't care to convince you to use anything, but at the same time i don't find it fair for you to "scare" other members into not trying it without "arguing" both sides.

[solbergfan]

Ok, your first problem is asking a dealer for info pertaining to the STi. There are very few that know anything about these cars. I've worked in the automotive industry for over 10 years and I have come to learn that most dealership parts guys are clueless.

Second, the OEM LSD oil is not synthetic, it is mineral based.

Third, I have ALLDATA here at work. The TSB # is TT0705-001. It specifically states that only the OEM Subaru LSD oil or equivalent can be used. If it is not used it will cause premature wear to the mechanical LSD. This TSB was issued because so many dealers were using normal gear oil in the STi rear diff and it was causing problems. The only equivalent oils I've found are Motul 90PA (which is what I use) and Silkolene 90 BOA LS. I don't think Subaru would have issued a TSB regarding this issue if it was not vital to have the proper fluid.

And yeah I understand that 90wt is a little thick in lower temps. But there is no multi-vis LSD oil, so oh well. It doesn't get much colder than low 20's in the winter here anyway.

[tripod]

Originally Posted by solbergfan

But there is no multi-vis LSD oil, so oh well

You are wrong. Again, you did not follow my link. And there is nothing wrong with multi-vis, and the Amsoil is for LSD's.

As I recalll the problem, people were using gl4 not gl5 spec oil. That is a no-no.

But, do as you wish.

[Blaiser]

solbergfan, loosin up, its not something to get mad about.

when it comes time to switch, i will use Asmoil

[Rac10000]

solbergfan, you better slow your roll.

BTW, I use Asmoil engine oil and have nothing but great things to say about it. Before the track season starts again, I am going to change my Tranny and Diff fluid to Amsoil.

[tripod]

Solbergfan
From the 2006 Subaru FACTORY Service Manual
page RM-2 Manual Trans API Standard GL-5, Rear Differential GL-5 for Mechanical LSD
From Page RM-3, from 32-110 F, 90
From -22 to 110 F, 75-90

Yes, the straight 90 is the recommended Only above 32 F!), but you need to apply some logic. in Chicago we go sub zero, I wouldn't run straight 90.

You 10 years in the industry do not impress me, I have been building and racing cars for over 35 years. You do not have the lock on knowledge, nor do you have an open mind.

[WolfPlayer]

I searched the service manual and came up with several references to the rearend gear oil. I tool all of these references and pasted them into a single picture for everybody to see.

http://www.bescaredracing.com/sti/misc/reardiff.JPG

I think this is a little confusing. First, some things are obvious. You absolutely need to use a GL-5 Gear Oil for MECHANICAL Limited Slip Differentials. That's a definite. Now, here is where it gets interesting. They recommend the Subaru 90WT LSD oil (90LSD) for STI models throughout the entire manual. When you look at the temperature scale it also recommends the straight 90WT gear oil. The main question is, are they recommending the OEM 90LSD oil for only that temp or are they recommending it for all temps. I think this is somewhat sketchy because you can read it both ways. However, to me it really seems like they are recommending the 90WT for all temps. They say that this is the recommended gear oil for the STI. They don't say it is the recommended gear oil for only that temperature. I can see how you could read it a different way though.

If the Subaru 90LS oil is only good down to 32d F then no way is SOA going to install that on the STIs stock right? But, they do. So, what gives? I've seen a similar TSB that says only to use the 90WT. So, I'm a little at a loss too. I'm currently running the stock Subaru 90LSD oil and after compiling all the references I have given above, I am happy with that choice even though it will get down to 0d F here.

http://www.bescaredracing.com/sti/dr...e/DSC06405.JPG

If anyone here can read japanese it would be awesome to get these translated PLEASE (I have much larger copies of these pictures with more detail if they are needed) ...
http://www.bescaredracing.com/sti/dr...e/DSC06403.JPG
http://www.bescaredracing.com/sti/dr...e/DSC06404.JPG

t

[tripod]

All in all, I am not much concerned. If you look at the warranty information on the Amsoil web site, they clearly will repaire or replace the partin question if failure was due to their lubricant. I have it in writing that the multi vis gear lube is appropriate for my car, so I am comfortable with my decision.
Everyone has their own comfort level, go with what you feel is right.