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Old 08-26-2003, 11:26 AM   #1
NotFast
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Default Change my tranny lube to synthetic

Well, after months of thinking and researching, I finally drained and refilled my MTL to Mobil 1 Synthetic (75W90) at roughly 17,000 miles. I had read some of the horror stories here about people having tranny problems after the swap. However, after searching a couple auto parts stores, M1 was ONLY 75W90 gear oil I could find.

Procedure: I followed the procedure from Scoobymods (http://scoobymods.com/forums/showthr...?threadid=1743), and it went smoothly. The old oil DOES stink REALLY bad, my garage still has the odor. Also, using a flexible funnel is highly recommended. I used a long neck stiff funnel, and ended up spilling some lube . Also, I found that I had to squeeze the bottle slowly, because the dipstick hole couldn't handle too much oil at one time.

Results: Before the swap, my transmission was fine - no problems, felt smooth and so on. I wasn't expecting much from the Mobil 1, but now the shifting is noticeably slicker and smoother. Hard to explain, but things just feel more lubricated inside the gearbox. No side effects - no grinding or weird sounds yet.

edit: corrected speeling error
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Last edited by NotFast; 08-26-2003 at 01:33 PM.
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Old 08-26-2003, 03:44 PM   #2
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I changed mine to Neo which I read in a mag that the Subaru rally team uses. I like it. The funnel is very important. I have one I picked up in the OIL change section of my local autoparts store for about $5. It allows me to measure in ounces, ml, quart. It has a flexible hose and ON/OFF valve which works very good for putting oil in a Subaru tranny. If you go too fast on the tranny you end up with expensive oil down the side of the tranny and all over the floor. With this cool funnel you just turn off the flow and wait a few seconds for air to escape then turn it back on. When your done you have the exact amount of oil in. For clean up just spray some brake cleaner in the funnel & wipe with paper towel.

I had to order my oil
http://bakerprecision.com/neo.htm
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Old 08-26-2003, 07:05 PM   #3
SidneyWRX
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That's what mine did for a while. Had no problems, changed to Mobil1 75W-90 and after about 4K miles, my 4th gear sycnhro started slipping. Changed it out and put redline in and it's gone, back to normal. Go to any race shop, they'll have what you're looking for, if not, they can get it next day usually. Would stay away from synthetics in tranny, usually don't give enough grip to the synchro's. I put Mobil1 in my rear diff and engine love it there, but redline all the way in my tranny. Just my .02
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Old 08-26-2003, 08:37 PM   #4
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Um, Redline IS synthetic--
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Old 08-26-2003, 09:17 PM   #5
badkid
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Default which redline?

Which Redline did you switch back to? Everyone says Redline Redline Redline. Redline comes in many flavors.

I wanna know if people are using MT-90 (GL-4) or 75W90 (GL-5) in their transmission box... and what results you're getting.
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Old 08-26-2003, 09:57 PM   #6
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Default Re: which redline?

Quote:
Originally posted by badkid
I wanna know if people are using MT-90 (GL-4) or 75W90 (GL-5) in their transmission box... and what results you're getting.
I think most people run RedLine 75W90NS in the transmission and 75W90 in the rear diff. Neither MTL nor MT90 are appropriate for the Subaru trans (they are GL-4 as you indicated) but there are at least a few people whom have tried it.

I use Motul Gear 300 in the engine and trans - works great!
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Old 08-26-2003, 10:56 PM   #7
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I'm very curious as to which Redline works best. I'll refer you to a Cobb Tuning article which actually recommends MT-90 in the transmission on Subarus.

MT-90 is a 75W90 gear oil and is of the proper and recommended viscosity. It's GL-4 and thus is not as slick as the GL-5 75W90 oil.

Before I make my first transmission fluid change, I'd like to collect more opinions.
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Old 08-27-2003, 07:32 AM   #8
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Quote:
Originally posted by badkid
MT-90 is a 75W90 gear oil and is of the proper and recommended viscosity. It's GL-4 and thus is not as slick as the GL-5 75W90 oil.
GL-4/GL-5 has more to do with the ability of the lubricant to handle high pressures and shear loads without falling apart. The GL-5 has more extreme pressure additives.
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Old 08-27-2003, 09:05 AM   #9
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It's a bit lengthy, but I found this quick explanation on transmission fluid/gear lubricants RE: GL-4 and GL-5. Based on this, I think I'd better get myself a GL-5 oil! Vroom vroom.


b. API In 1965, API determined service classifications for gear lubricants based on their use. At that time, GL-1 through Gl-5 were issued, with GL-6 being added later.

API GL-1 is essentially a mineral oil for manual transmission and spiral-bevel axles plus worm-gear service satisfied by non-compounded oils.

API GL-2 is treated with very mild EP additive for automotive worm-gears not satisfied by non-compounded oils.

API GL-3 is treated with mild EP additive for manual transmissions and spiral-bevel axles operating under moderately severe conditions of speed and load.

API GL-4 is treated with medium level of EP additive suitable for lubrication of hypoid gears in moderate service. It is roughly equivalent to MIL-L-2105.

API GL-5 is treated with high levels of EP additive suitable for hypoid gears operated under high-speed, shock-load; high-speed, low torque; and low-speed, high torque conditions. This classification is usually equivalent to MIL-L-2105B

API GL-6 is treated with a very high level of EP additive for high offset hypoid gears (above 10 cm offset and approaching 25% of ring gear diameter) and other automotive equipment operated under high-speed, high performance conditions.

c. Limited Slip Differentials In addition to the above performance characteristics, gear lubricants going into limited-slip differentials service require the addition of a frictional modifier. A limited-slip differential allows the axles to turn at different speeds when on dry pavement buy will restrict differential action when on a slippery surface.

This system employs a slow-moving clutch which tends to "stick-slip" at low sliding velocities unless the gear lubricant contains the proper frictional properties. The "stick-slip" action produces loud chatter noises and severe vehicle vibrations.
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Old 08-27-2003, 10:52 AM   #10
DerFahrer
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Here is the final word on gear oils in Subaru manual transmissions...

Of course my Legacy has over 120k and choosing gear oils gets touchy at that mileage...

Synthetic is simply too slick. There is not enough friction between the synchro cones to allow the gears to engage properly when synthetic oil is used.

I tried Redline 75W90NS for a while, was grinding gears left and right, so upon suggestion, as mentioned before, I used Redline MT-90 (GL4) and 75W90NS, half and half. It pretty much solved the problem.

But after a bad axle seal leak developed on the car, and having to put whatever gear oil I could get in the tranny to keep it full, I got the leak fixed and had some 6 different types of gear oil in the tranny.

I changed the gear oil one last time, putting straight Castrol dino oil in it, and have not ground a gear since...

Regular dino oil is the best for Subaru manual transmissions.
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Old 08-27-2003, 11:47 AM   #11
NotFast
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Default

Quote:
Originally posted by subyluvr2212
Regular dino oil is the best for Subaru manual transmissions.
Okay, I'll repeat this -- where do you buy dino 75W90 fluid?? Without resorting to buying online or at my Suby dealer, where, where, where? A guy at my auto parts store told me that finding it would be "difficult" and neither they nor the other store I checked carried it.

Heck, my local Pep Boys didn't carry ANY MTL.
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Old 08-27-2003, 03:41 PM   #12
DerFahrer
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The guy at your local auto parts store must not be too bright of a guy.

Any parts place should carry either 75W90 gear oil or 80W90 gear oil. In fact, that's all manual transmission lubricant (MTL) is!

That's all you need. Either one of those is A-OK. Just make sure there is no synthetic anything in it, even partial synthetics are bad for Subaru MT's, I know. Don't look for anything fancy.
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Old 08-29-2003, 06:02 AM   #13
Barry
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Default Another alternative...................

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Old 08-29-2003, 10:08 AM   #14
NotFast
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Default Re: Another alternative...................

Quote:
Originally posted by Barry
http://forums.nasioc.com/forums/show...hreadid=395483

Interesting... thanks Barry.
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Old 08-30-2003, 09:43 AM   #15
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I've been using Motul Gear 300 for the last 12,000 miles and have been quite happy with it. I haven't had any crunchy shifts, but I subscribe to the Mike Shields theory of shifting. The trans feels much better in the cold than the stock dino fluid. You should be able to get it at a local motorcycle shop.
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Old 08-31-2003, 01:01 PM   #16
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See if you can find Redline Superlightweight Shockproof Gear oil , I have had it in my rs tranny for 35000 no problems and a buddy put it in his 02 wrx tranny and has yet to grind a gear .
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Old 09-04-2003, 03:03 AM   #17
aspera
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Default

Quote:
Originally posted by subyluvr2212

Synthetic is simply too slick. There is not enough friction between the synchro cones to allow the gears to engage properly when synthetic oil is used.

I tried Redline 75W90NS for a while, was grinding gears left and right, so upon suggestion, as mentioned before, I used Redline MT-90 (GL4) and 75W90NS, half and half. It pretty much solved the problem
The "NS" doesn't have the friction modifiers and is recommended for racing and offroad use. Could this be the problem? Maybe the regular 75W90 (not NS) is a better option. I just have a problem buying that an oil is too slick. Isn't that what it is supposed to be?

http://www.subaruparts.com/catalog/?section=271

This site lists a bunch of Redline oils. The shockproof ones seem interesting.

EDIT: Well after reading the technical specs on Redline's website, I know better. Regular 75W90 would be used with plate-type LSDs that are IN the oil. 75W90NS would be used on a WRX because both of the LSDs are 'dry'. The front differential is open, so it doesn't need the friction modifiers either.

It also seems that a GL5 oil is recommended by Subaru for the WRX tranny and rear diff. GL5 oils seem to be needed for the slow, high pressure needs of a differential, while GL4 oils work better in a tranny. (That's my understanding)

So you should use GL5 in the rear diff and GL4 in the tranny then right? I don't think so. Remember, the WRX also has a differential in the front tranny. I think the factory recommended GL5 is what's needed all around.

What is really needed is a transmission that seperates the front diff oil from the tranny oil so that different kinds can be used. Oh wait! Doesn't the new 6 speed do that? I'm guessing that it can use two different oils. It also has a different kind of rear LSD, so it might need friction additives.

After all that, I'm prolly going to use Redline Shockproof LightWeight for my 5 speed. I just put Mobil 1 in the rear diff...it was IN STOCK and ready to rock.

Last edited by aspera; 09-04-2003 at 09:57 PM.
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Old 09-04-2003, 03:25 AM   #18
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I have the lightweight shockproof in my tranny and love it. Had mobil1 and it was to slick, my 4th gear synchro was starting to slip. Put redline in and it's all better! Nothing but redline from now on in all my trannies!
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Old 09-04-2003, 11:55 AM   #19
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I've had amsoil 7500 in the trans and rear for a while now. I thought it was a nice improvement over the doody that was in there.

No side affects
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Old 09-04-2003, 01:37 PM   #20
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Amsoil is good stuff.....

If anyone is interested, I am a dealer and can for a small fee get anyone else set up so u can recieve the product at a great price....
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Old 09-06-2003, 01:56 PM   #21
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Wanna PM me a price shipped for a case of the 7500?
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Old 09-08-2003, 09:42 AM   #22
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Quote:
Originally posted by moogoob
I've had amsoil 7500 in the trans and rear for a while now.
If you have 7500 in your diffs, you should change it now.
7500 is Engine Oil .

The gear oil is called Gear Lube .

-Dennis
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Old 09-08-2003, 05:41 PM   #23
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yup, just a typing errrr.... have gear lube, just not the 2000 stuff
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Old 09-09-2003, 03:51 PM   #24
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so wait.. is gear oil transmission fluid? i mean are they the same thing??? like " i drain my tranny and put redline gear oil in?" is that right?
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Old 09-09-2003, 05:06 PM   #25
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Ordinary gear oil is designed for certain uses, chiefly heavy-duty protection for "standard" gearing, such as in a differential, and has its own series of grades which tend to differ in the amount of high-pressure wear agents etc.
Transmissions need gear protection, but many also need specific levels of friction in their fluid to work properly. Many also contain bronze synchros and so may need formulations/additives to prevent corrosion of the bronze.
Bottom line: most any gear oil will work in e.g. a rear diff, but depending on the manual transmission, some will just use standard gear oil, some will use standard motor oil (!), some need a gear oil designed for manual transmissions. Unless you've researched it pretty carefully, I wouldn't change from what the manufacturer put in. The types of problems you run into tend not to be immediate, but rather needing new synchros in 15k miles or things like that that aren't cheap.
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