What Tranny fluid to use?

Imprezive · Post by **Imprezive** » Sun Nov 05, 2006 5:25 pm

Ok, this might sound like a dumb thing to ask, but i did search a bit and found all the jazz about "Uncles scotty's synchro fix" blah blah blah. What what if your synchros and just dandy and you dont need anything to be fixed? My tranny is in PERFECT condition, its as good as my parent's 1999 outback

I basically just want to replace the old crap with some new stuff, will uncle scotty's still work fine??

adema2626 · Post by **adema2626** » Mon Nov 06, 2006 6:58 am

i like Redline MT-90

free5ty1e · Post by **free5ty1e** » Mon Nov 06, 2006 4:52 pm

Isnt MT-90 a GL-4 lube? We need GL-5 for our front diffs, not just any gear oil / synthetic will do. I'd suggest if you're not gonna use Uncle Scotty's cocktail (which I have in my low-mile WRX tranny, which did not "need" it but still seems to benefit from it nonetheless), then at least use the Hypoy C Gear Oil, which is GL-5 rated and designed to protect our hypoid differential and the attached tranny at the same time.

realfinn · Post by **realfinn** » Mon Nov 06, 2006 5:12 pm

Just keep in mind that if you go to a synthetic on a seasoned tranny you will probably see some leaking.

Imprezive · Post by **Imprezive** » Mon Nov 06, 2006 6:44 pm

Well its not that I dont want to go with the Scotty mix, I just wasnt sure if it was the better choice...

skid542 · Post by **skid542** » Mon Nov 06, 2006 7:39 pm

Sorry for the short hijack.

Do all Subaru transmissions, or atleast the 90-91+, have the hypoid diffs and require the GL-5?

BAC5.2 · Post by **BAC5.2** » Mon Nov 06, 2006 7:58 pm

realfinn wrote:Just keep in mind that if you go to a synthetic on a seasoned tranny you will probably see some leaking.

No it wont. My 160,000 mile Forester has zero trans leakage issues.

I HIGHLY recommend against using Uncle Scotty's cocktail. GM Syncromesh/Pennzoil Syncromesh is a GL-4 fluid. It's exactly what isn't recommended for our transmissions. Redline's Lightweight Shockproof isn't technically recommended for syncronized transmissions, but by Redline's own admission that was only done to prevent having to subject the fluid to API testing (which is expensive).

I recommend using 3 quarts of Motul's Gear300 75W90, and 1 quart of Redline's Lightweight Shockproof (if you feel like shifting is a bit notchy).

You can use a really high quality synthetic 75w90, but you might notice some grinding when going into gear. It's a common problem with Mobil1 that people notice. There isn't enough friction for the syncronizers to properly function. That's where the quart of Redline's Lightweight Shockproof comes in.

We've put 30k on pure shockproof, and seen no adverse effects upon transmission teardown. We've even got a 55 gallon drum of the stuff sitting in the corner. It's good fluid.

realfinn · Post by **realfinn** » Tue Nov 07, 2006 1:04 am

A lot of people get lucky...but if I was serious about my car I would reseal it before I went synthetic.

Anyone got any opinions on the Lucas gear oils?

BAC5.2 · Post by **BAC5.2** » Wed Nov 08, 2006 12:39 pm

Why would you reseal it? Why would switching from dino oil to synthetic, even at high miles, would cause leakage?

realfinn · Post by **realfinn** » Wed Nov 08, 2006 2:54 pm

Phil I think your partially right on this. But what I'm saying is that some companies put detergents in there fluids. When detergents are added they break up deposits. No, a deposit isn't going to stop oil from spraying everywhere but what it will do is keep a small leak plugged up. When the detergent removes the deposit a small leak can start.

I guess if I was going to go to a synthetic I would make sure it was not packed with detergents.

Post by **Legacy777** » Thu Nov 09, 2006 1:41 am

To be honest....I think with most modern oils & modern seal material, you really don't need to worry as much about the crud building up at the seals and keeping the oil from leaking out.

BAC5.2 · Post by **BAC5.2** » Thu Nov 09, 2006 4:58 am

But there isn't any time that the fluid is stagnant enough to allow deposits to collect, drying a seal to the point of allowing it to decay.

Not very many detergents are found in transmission fluids. It's not a high-deposit situation. There isn't really excessive heat, and there really isn't anything to cause deposits.

But if you feel it's necessary to tear down the transmission, replace the seals, and rebuild it before changing transmission fluid, then that's cool. The parts aren't expensive, but it's labor intensive to remove, tear down, rebuild, and reinstall a transmission.

93forestpearl · Post by **93forestpearl** » Thu Nov 09, 2006 5:34 am

FWIW, Redline 75w90NS gave me a grinding 1-2 after about 50k in my freshly rebuilt 5mt.

Phil, was I right about those stubs? You haven't replied.

Imprezive · Post by **Imprezive** » Thu Nov 09, 2006 5:43 am

Soooo, does anyone have any opposition to the Motul?

BAC5.2 · Post by **BAC5.2** » Thu Nov 09, 2006 5:44 am

Dan,

Sorry mate, haven't had much free time. Most posts are via treo.

It HAS to be the stubs though.

The part number I gave you looks to be the correct part number for the proper stubs. I'm not sure why yours don't work.

Phil

BAC5.2 · Post by **BAC5.2** » Thu Nov 09, 2006 5:51 am

Dan,

Yep, I've confirmed. You need 2x 38415AA110. The 5-speed stubs are 38415AA100, which are the same across all model year 5-speed stubbed transmissions. The 110 part number is the early 04 6-speed that was stubbed. Those are the stubs needed to use your stock axles.

You also need one of each of these, the axle seals for the stubbed transmission. I think we covered it though: Left - 806730041 Right - 806730042

Phil

Imprezive · Post by **Imprezive** » Fri Nov 10, 2006 5:38 pm

answer?

BAC5.2 · Post by **BAC5.2** » Sun Nov 12, 2006 10:12 pm

No opposition to the Motul. It's good stuff. Good enough for WRC racing

Imprezive · Post by **Imprezive** » Mon Nov 13, 2006 1:46 am

oh well then its good enough for me haha!

Well shifting is perfect right now. (except 1st to 2nd grind a little if I am shifting super fast)

So I want it to stay the same. When its in gear I can wobble it a bit but thats because of the bushings I am guessing.

Will the tranny hold 4 quarts of fluid? That motul stuff is expensive!

BAC5.2 · Post by **BAC5.2** » Wed Nov 15, 2006 7:22 pm

It'll probably take about 3.7 quarts.

How much are you seeing the Motul for? We sell it for like $13.88 a quart.

John Drivesabox · Post by **John Drivesabox** » Sat Nov 18, 2006 2:49 am

realfinn wrote: Anyone got any opinions on the Lucas gear oils?

Just like the quote from the movie, I say....

"PUT LUCAS IN!!!!!!!!!"

Sorry, I always wanted to use that somewhere. Seriously, I have Lucas in my rear diff and it works great.

Imprezive · Post by **Imprezive** » Sat Nov 18, 2006 5:35 pm

Ok here are some prices from PDM:

Motul 75W90 Synthetic Blend Gearbox oil(15.64 each) for one liter

Motul Gear 300 75W90 100% Ester Synthetic(24.11 each) also for one liter.

Edit: HOLY CRAP, I just went to a site called NGPRACING.COM and they have the Motul Gear 300 for $12 per liter!

I'll have to do some reading.

Imprezive · Post by **Imprezive** » Tue Nov 21, 2006 7:36 pm

I am thinking I might just get Motul Synthetic blend 75w90.And add a quart of shockproof. But first I am going to add some Redline 75W90 to see what happens. Should I not add redline to the stock tranny fluid?

skid542 · Post by **skid542** » Tue Nov 21, 2006 8:02 pm

I can't answer your specific question Imprezive but I did just want to add to this thread since I changed my fluid the other day.

3 days ago I changed my fluid and used Valvoline non-synthetic and everything has been just fine. It's GL-5 but shifting has been smooth and my 1-2 is great and doesn't have the issues it used if I try to shift fast. I'm only a lowly NA so high power demands might changes things but I've been pleased.

spongejosh · Post by **spongejosh** » Thu Nov 23, 2006 11:14 am

i wouldn't add synthetic to your stock dino oil. it could be bad.

i use royal purple. half a quart of RP Synchromax and then fill the rest with RP Maxgear 75w-90. the royal purple is expensive but i love it. no problems after 30k in my wrx and just put it in the t-leg. 170k on the tranny and no leaking yet.

josh

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What Tranny fluid to use?

What Tranny fluid to use?