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Manual Transmission Fluid


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Hey fellas, doing my tranny fluid and just want to ask before i act: Do those 4 bolts sureounding the shifter need to come off to be able to fill, or do I just pour it in that small hole on the side of the shifter?  

 

https://i.4cdn.org/o/1683840568892282.jpg

Edited by Pathfinger
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I have found that either removing the shifter or shifter housing is more than adequate. Also make sure you have GL4 Transmission fluid or the transmission will have problems.

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You mean overpriced stuff? You can get Valvoline MTF for about $10 a quart at your local auto parts store. Should I mention it meets the specifications?!

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  • Pathfinger changed the title to Manual Transmission Fluid

Why use a manual transmission fluid to a diff.that requires a diff fluid?

 

I used Castrol 80w-90 with Limited slip additive built in and it does well

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20230520_153749.jpg

 

20230520_172047.jpg

 

Got it done. Taking off the shifter plate was much faster than messing around with snapring pliers.  Now it's time to get my interior back in...

20230520_211732.jpg

 

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  • 1 year later...

Sorry to resurrect an old thread but here we are.

 

I think I've read the the fill plug is too low on the early manual transmissions? It doesn't allow enough fluid to be added? (We have a 1993 XE 5spd 4x4) 

What is the actual fill amount by volume if the fill plug is unreliable?

Is removing the boot and the four bolts on top of the tranny and filling from inside the cabin the best way?

 

Thanks!

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Yep, early (pre 4/'96) fill level was too low, which starves the countershaft bearings. There's a TSB for replacing the whole trans case with one that's got the fill hole about an inch higher up, but in the real world, you can just dump another 1.5L into it by removing the shifter. The original spec was 3.6L. New spec is 5.1L.

 

Info/instructions here. Note the oil spec! Do not use a GL-5 rated oil.

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Thanks Slart. 

Sounds like Redline MT90 is the go-to around here? 

Any experience with Valvoline Synchromesh mentioned in this thread? 

 

Man, pulling that shifter boot out from under the carpet was a bugger when we dropped the tranny. Had I known at the time that the fill plug was unreliable I would have made sure we did that during clutch replacement. 😡 I just wanted to get the job done and assumed we could side fill it later.

Edited by Aonghus
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21 hours ago, Aonghus said:

Thanks Slart. 

Sounds like Redline MT90 is the go-to around here? 

Any experience with Valvoline Synchromesh mentioned in this thread? 

 

Man, pulling that shifter boot out from under the carpet was a bugger when we dropped the tranny. Had I known at the time that the fill plug was unreliable I would have made sure we did that during clutch replacement. 😡 I just wanted to get the job done and assumed we could side fill it later.

I run ATF Dex III in mine at the recommendation of the bloke who rebuilt my trans. Has never shifted so nicely. 

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12 minutes ago, FirstGenFreak said:

I run ATF Dex III in mine at the recommendation of the bloke who rebuilt my trans. Has never shifted so nicely. 

Really? Good enough grip for the synchros? Any thoughts about using that in an older transmission?

That makes me wonder about the Synchromesh then, pretty sure that is in a similar viscosity range as ATF...

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3 hours ago, Slartibartfast said:

I've heard of people jacking up one side/parking on a slope so the fill hole is higher. Might be worth a shot.

I wondered the same thing and thought we might as well try it.

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For the sake of gathering info on this topic, here's a link to some of the most thorough info from the BITOG forum with all the tested and dedicated manual transmission fluids grouped by kinematic viscosity at 100°C or the rough average operating temperature. In case you want to follow me down the rabbit hole. 😅

 

As I understand it,75w-90 GL-4 fluid was originally recommended for these manual trannys but that was later revised to 75w-85. However all these dedicated MTF/MTL options didn't exist back then, in 1993 in my case.

 

So, here's what I know at this point, I think:

 -  75w-90 is ~14.5cSt, original spec

 -  75w-85 is ~12cSt, revised spec

 -  There has been a trend towards lower KV fluids over the last 20 years, improve, shifting, better flow in cold temps.

 -  The advances in additive packages makes lower KV fluids possible without sacrificing high temp cushion and lubricity

 -  API GL-4 is a necessity, not GL-5 or 4+ or whatever else, especially in an older trans.

 

So it seems to me, going by the info I've gathered, something in the 10cSt is probably where I want to be, slightly lighter weight than the 14.5cSt 75w-90 originally recommended and close to the 75w-85 revision. If I can find it, which is proving a little difficult. ATF is in the 6-7cSt range and seems too thin in my case but I can understand it may be great in a freshly rebuilt MT. If that's what a builder recommended then definitely go with it.

 

Valvoline Synchromesh is the ONLY GL-4 MTF option I've found in my town and it's currently $9/qt at O'Reilly's. I cannot get my hands on a standard 75w-90 GL-4 fluid locally.

 

At ~9.2-9.4 cSt the Valvoline Synchromesh is a touch lighter than I'd like but it's available locally and relatively well priced. So I'll give it a go and report our experience. The good thing is this old Pathfinder isn't yet a *needed daily driver so it could sit for a bit if it doesn't work well and I still need to special order Redline MT-90 at $20/qt.

 

 

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Good to see I'm not the only one exploring random rabbit holes. :) Your conclusion sounds reasonable to me.

 

And yeah, I don't see why ATF wouldn't work. That's what the Tremec T-5 in my dad's hot rod takes.

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Well if you want to go down the rabbit hole with me, how about John Deere HyGard? 😀

 

It is GL-4 rated, and designed for very high pressure and torque applications in modern hydraulic tractor transmissions. In these applications it serves as both a transmission gear oil and a hydraulic fluid. 

 

The standard Hy Gard is 9.4cSt. It contains wear reduction additives similar to MT fluids. But I can't find any specific information for a true manual transmission, it just seems to meet all the right specs. It's $32/gal locally or $134/5gal.

 

The LowVis version (7.4cSt) is being used in auto transmissions by some of the Cummins diesel guys, I'm gonna try it this summer in my 2nd gen Ram 2500. Users are reporting excellent/firmer shifts, grab, and long life and cleanliness when changed.

 

I have a PDF but it's apparently too large to attach.

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I have used Redline MT90, MTL, Valvoline Syncromesh, some random store brand 75w90 and a couple others.

 

Everyone on this board loved MT90, they must all live in the desert because here in Canada, it was the worst cold weather shifting I've ever had, constant grinding into 2nd for the first few km, the ancient probably factory fill was better, but warmed up it was fine. The redline MTL is what I have now, works much better. I never did try MT85 and suspect it would be a bit better and according to the BITOG thread "MT-85 exists mostly for Nissan vehicles which spec 75W-85" lol.

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Hey thanks that's helpful experience! 

We live in NE Oregon where temperatures vary considerably. We'll usually get over 100F in the summer for a bit and sub-0F in the winter for a bit. Coldest I've seen here is -22F and the hottest was 112F. There's usually several weeks in the winter when doesn't get above freezing at all. That factors into my consideration for a lighter weight transmission fluid. Whatever is in it now is notchy going into 2nd when it's cold in the morning.

 

I'll check out the specs for the Redline MTL and see what I can find.

 

EDIT: Redline MTL is 10.4cSt

That's great!

Edited by Aonghus
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Following this, because I remember one of my shifts being grindy, but can't remember which one...also used MT-90, and thought I over-filled it but it's been so long I can't remember!

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