Official Fluids Thread

[MattR]

So, to continue with our conversation last night...What are the preferred fluids for 5MT/ 6Mt Transmissions.

You guys recommended the Redline Shockproof 75w90NS...

Does this have any effect on the DCCD in the STi transmission? I've looked around and haven't been able to find any negative effects, so I'm assuming it will be okay.

Any input?

Also, do I need a new plug gasket to replace when I change my fluid, or is it reusable?

[Dean]

I personally would reccomend the Subaru factory fluid. They have spent a considerable amount of time balancing the needs of the transmission and diff. Anything else at best is an educated guess IMHO.

Unless there is a compelling reason, I wouldn't change. Have you had issues with the transmission with the factory fluid?

[MikeK]

Originally Posted by Dean

I personally would reccomend the Subaru factory fluid.

I disconcur with this. My transmission shifted like arse on the factory fluid. I am sure you guys are sick of hearing about me bitch about it by now. Last month before thunderhill Nate put redline lightweight shockproof in and the difference has been night and day. The shifting is smooth, no grinds, and it is much easier to get into first now.

[Dean]

Originally Posted by MikeK

I disconcur with this. My transmission shifted like arse on the factory fluid. I am sure you guys are sick of hearing about me bitch about it by now. Last month before thunderhill Nate put redline lightweight shockproof in and the difference has been night and day. The shifting is smooth, no grinds, and it is much easier to get into first now.

I understand you have had issues, but do we know the impact of having the shockproof in the diff?

I have the stock fluid in my 02, and have had no problems at all, and I slam first like nobody's business.

All I am saying is that Subaru engineers proabably spent many hours selecting te right fluid for the complete system covered by that fluid, and if it ain't broke, don't fix it.

If you are having a specific issue, talk to knowledgeable people and try something, but understand the risks involved in doing so. I personally have know idea what any fluid will do to the diff, and tranny combination in the STI.

[MikeK]

Originally Posted by Dean

I understand you have had issues, but do we know the impact of having the shockproof in the diff?

The impact is that I no longer want to drive my car off a cliff

Originally Posted by Dean

If you are having a specific issue, talk to knowledgeable people and try something, but understand the risks involved in doing so. I personally have know idea what any fluid will do to the diff, and tranny combination in the STI.

I just went with what Nate recommended. I asked for a fluid change and told him the problems and he recommended the lightweight shockproof. If I can't trust Nate's judgement whose can I trust?

[Nick Koan]

What kind of problems do improper fluids present? How does the oil in the gearbox affect the differentials? (I think I have an idea, but I'm not quite sure if it is correct or not).

[sperry]

Originally Posted by MattR

So, to continue with our conversation last night...What are the preferred fluids for 5MT/ 6Mt Transmissions.

You guys recommended the Redline Shockproof 75w90NS...

Does this have any effect on the DCCD in the STi transmission? I've looked around and haven't been able to find any negative effects, so I'm assuming it will be okay.

Any input?

Also, do I need a new plug gasket to replace when I change my fluid, or is it reusable?

RedLine 75w90ns is *not* Shockproof!

Here's a summary of the Redline gear oils applicable for our Subarus:

Redline 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."

This is good for the tranny if you're concerned with staying with a GL-5 oil. Frankly, I think it's too slick for the synchros, and will cause the tranny to shift poorly unless you're willing to double-clutch and rev-match more often than not.

Redline 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."

I use this in my rear-diff. But it's not for use in the gearbox, due to the poor synchro performance that would result.

Redline Lightweight Shockproof:

"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. May be used to obtain maximum power transfer in racing differentials which do not see high temperatures. Similar to a 75W140 gear oil, but with the lower internal friction of an SAE 30 motor oil.

Used in two-stroke and four-stroke motocross transmissions (often mixed in equal parts with SuperLight ShockProof™ Gear Oil).

Used in most road-racing differentials with moderate power and dogring racing transaxles."

This is what I'd recommend. I'm actually using a 50-50 mix of Lightweight and 75w90ns, but I've run the straight shockproof before and liked it better (better synchro grab).

[JoelK]

I just want to add one thing.

I emailed Subaru a while back asking about synthetic diff fluids. They recommend the fluid they use simply because it's what they tested. The other fluids just haven't been tested.

Personally, I believe that synthetics are often superior to dino fluids. Obviously, care has to be taken so that an incorrect fluid is installed (too slippery or too thick), but I think there are enough people out there that have driven many miles on synthetics that I have no problems using that when my maintenance date arrives.

[sperry]

Originally Posted by Dean

I understand you have had issues, but do we know the impact of having the shockproof in the diff?

I have the stock fluid in my 02, and have had no problems at all, and I slam first like nobody's business.

All I am saying is that Subaru engineers proabably spent many hours selecting te right fluid for the complete system covered by that fluid, and if it ain't broke, don't fix it.

If you are having a specific issue, talk to knowledgeable people and try something, but understand the risks involved in doing so. I personally have know idea what any fluid will do to the diff, and tranny combination in the STI.

Shockproof is essentially a 90w140(ns?) weight oil with a property that makes is stick to *everything* creating a coating layer that won't spin off gears easily. In fact, it's damn near impossible to drain a tranny of the stuff unless you get the gearbox nice and hot 1st.

I don't know about using the oil in a diff, but if it performs as well as a "regular" synthetic in the diff regarding the proper amount of friction, plus it sticks to the gears to provide a layer of protection against gear shock, then I can't imagine there's a downside to the stuff aside from cost and possible warranty issues (as it's not a GL-5 oil technically).

As far as "if it ain't broke"... most people w/ Subarus *do* think "it's broke". I know I *hated* shifting my car before the switch to synthetics. It's still not as easy as I think it should be, but at least now it's consistant. I used to grind all sorts of gears shifting... and not even speed shifting. Now with the Redline oil, I can go 1-2-3-4-5 as fast as possible with no issues, and only a quick downshift to 1st requires double clutching to avoid grinding.

The only point of contention to me is "how is the 6MT different from the WRX's 5MT?" I don't think there's really any significant difference that would affect oil selection, but I don't know that for sure. However, if Nate were to recommend it, then I'm on board, since that meshes with my experience w/ gear oils.

[MattR]

Ok, cool, I couldn;t find the shockproof on the website, but I see it now,

Anyway, I just had a conversation with Nate, and the STi Tranny responds well to the shockproof, I think I'm going to give it a try. He did caution me to keep the OEM style fluid in the rear diff, it is the best match for that application, I have a new rear diff anyway, so I have no need to change the fluid. But overall feeling is that the Shockproof in the tranny is positive and totally safe.

I'm gonna swing by summit after work and pick some up.

[sybir]

Originally Posted by MattR

Ok, cool, I couldn;t find the shockproof on the website, but I see it now,

Anyway, I just had a conversation with Nate, and the STi Tranny responds well to the shockproof, I think I'm going to give it a try. He did caution me to keep the OEM style fluid in the rear diff, it is the best match for that application, I have a new rear diff anyway, so I have no need to change the fluid. But overall feeling is that the Shockproof in the tranny is positive and totally safe.

I'm gonna swing by summit after work and pick some up.

Derail: is Summit open on Saturdays? I need to pick up some exhaust pieces.....

[Dean]

Originally Posted by sybir

Derail: is Summit open on Saturdays? I need to pick up some exhaust pieces.....

Yes, 9-9 IIRC

[sybir]

Excellent.
Thanks.

[Dean]

Stupid question... I was making the foolish assumption that the Subarus had common fluid for the trans, and at least 1 diff like the Stealth. Is that not the case?

[sperry]

Originally Posted by Dean

Stupid question... I was making the foolish assumption that the Subarus had common fluid for the trans, and at least 1 diff like the Stealth. Is that not the case?

The Suby tranny is spec'd for GL-5 in the tranny, which lubes the gears/synchros, front and middle diff. (at least I don't think the front or middle diffs are sealed) I think the rear diff is also spec'd for GL-5, but don't quote me on that...

[Dean]

Originally Posted by sperry

The Suby tranny is spec'd for GL-5 in the tranny, which lubes the gears/synchros, front and middle diff. (at least I don't think the front or middle diffs are sealed) I think the rear diff is also spec'd for GL-5, but don't quote me on that...

In the stealth, this is a big issue, because the Gertrag tranny sucks so bad, you need a fluid that is as soft on the synchros as possible. Unfortunately, this often makes the front diff unhappy as they share fluid.

[qksubi]

I have never done any cars I have had a bunch motorcycles /dirt bikes and that is the first thing I do and night and day shifting and clutch ingagement is much quiker but that is on motorcycles :?

[sperry]

Originally Posted by qksubi

I have never done any cars I have had a bunch motorcycles /dirt bikes and that is the first thing I do and night and day shifting and clutch ingagement is much quiker but that is on motorcycles :?

Isn't the SuperLight Shockproof really popular for bike trannys?

[MattR]

Originally Posted by sperry

Isn't the SuperLight Shockproof really popular for bike trannys?

I think Eric said he was using the Motul in the bikes, but the redline was his second choice.

[qksubi]

Originally Posted by sperry

Isn't the SuperLight Shockproof really popular for bike trannys?

For the smaller Bikes like Zacks 65cc but I just looked and I have none so I dont know the wt of gear oil it was when he did race it didnt last very long mybe 2 races

[MattR]

Okay, so Eric and I swapped the Shockproof Fluid into the STi Trannies tonight. WOW! What a noticeable improvement to an already wonderful tranny. Honestly, it is absolutely the best feeling tranny ever now.

To Make sure, we had our resident GT driver Nick take them out for a spin...He came back with a smile, and commmented that the difference is overwhelming...

So, THUMBS UP on the Redline Shockproof.!

[AtomicLabMonkey]

Works good on a T-5, anyway...

Ok, I'll shut up now.

[Kevin M]

Originally Posted by AtomicLabMonkey

Works good on a T-5, anyway...

Ok, I'll shut up now.

I did a big when my dad told me his Ranger 4x4 responded really well to ATF in the gearbox.

I guess we better fill you in on why we have this discussion on this board- normal, really good synthetics, are really bad for our synchros. Great for the gears and bearings, but they are so slick they make the synchros work REALLY slow which causes grinding, which is a lot worse than slightly accelerated bearing wear. That's why Matt and Eric love the shockproof so much.

[WRXRallyBlue]

How many quarts would I need to buy? Also, I need to pick up some diff fluid. I'd just as soon get everything once from summit, what do you guys suggest?

[Kevin M]

you need 4 quarts for the gearbox. 3.7 actually, and a coupel of us have partial quarts you can use for the diff. I think that's .8 quarts? something really close to 1.