[bparrishlvx]

I don't claim to know much about anything, but I have enough common sense to know when something does not sound right. I purchased a Muncie M-21 today from a guy that told me he has run ATF in Muncie's exclusivley for years and years. Of course I took the bait and asked why would you do that....

"Aluminum case ATF, Steel case gear lube".

Is there any logic to this methodoligy? Of course automatic transmissions are aluminum and run ATF, rear diff's are steel and use gear oil but have any of you heard of this? I have read hundreds of magazines and been around cars and rodding as long as I can remember and have never heard of this.

Please educate.

Thanks

 

[DZAUTO]

First of all--------------I don't think so. :noway:
BUUUUUUUUUUUUT, on the other hand, I have zero experience with running ATF in a tranny such as a Muncie, T-10, etc.
Here is what I DO have experience with.
The 5sp manual trannys of the 70s, made by Borg-Warner, that were used behind V6s and small V8s DID use ATF. My 76 Olds Cutlass, that I special ordered new with a 5sp (and still have), used ATF in the tranny. It took a looooooooooooong time for me to accept that (ATF) as being the correct lube! But, I finally accepted it. I went through 3 of those trannys (they were hard to find in salvage yards--------------and a b!$#h to rebuild!!!! I hate 'um!!!!!). About 1987, I built a healthy Olds 455 to replace the original small V8 and had to locate a tranny to go behind it. I bought a Richmond 5sp----------------which uses 80w90 gear oil. It is an alum case. Richmond also makes (bought the design from B-W) the Super T-10------------it uses gear oil, case is alum. The "new" Autogear Muncie uses gear oil-----------------its an alum case.
COULD ATF be used in a tranny such as a Muncie? Maybe.
Why didn't GM recommend ATF for their 4sp trannys? Ummmmmmmmmm, maybe with all of their years of engineering expertise and millions of dollars of R&D allowed them to conclude gear oil was the most appropriate lube to use in an alum case manual tranny.
I'm thinking you better walk away from this guy. :yes:
I can't speak for people such as Wally and Jody, but I've been building/repairing 4sp trannys for 40+yrs, and so far, I haven't seen a failure of an alum case manual tranny because it had gear oil instead of ATF. :thumbsup:

 

[Keith Tedford]

I've put way over 200K miles on Muncies with 80W90 gear oil. The Super T-10 that we put in our '72 Lemans also used the 80W90. When I had the M21 in our Chevelle overhauled a few years ago, the mechanic had me get the 80W90 gear oil. He wouldn't use it. It had to be the GM gear oil as it was the only stuff that he trusted. He has the reputation of being about the best mechanic in our area so I trust his judgment. Do any of the high horsepower newer applications use transmission fluid in the standard transmissions? I know that some low horsepower applications do. I would definitely side with Tom on this one.

 

[Verle]

I've put way over 200K miles on Muncies with 80W90 gear oil. The Super T-10 that we put in our '72 Lemans also used the 80W90. When I had the M21 in our Chevelle overhauled a few years ago, the mechanic had me get the 80W90 gear oil. He wouldn't use it. It had to be the GM gear oil as it was the only stuff that he trusted. He has the reputation of being about the best mechanic in our area so I trust his judgment. Do any of the high horsepower newer applications use transmission fluid in the standard transmissions? I know that some low horsepower applications do. I would definitely side with Tom on this one.

Late model Corvettes use "ATF" in manual transmissions, including the ZO6.

It depends on what the transmission was designed for.

I have used 80W90 gear lube in my aluminum case 4-speeds since 1962. I have heard of people running ATF in Muncie 4-speeds but I am not willing to try it.

Verle

 

[tom69chevymalibu]

I run 80w-90 gear oil in my muncie's. That is what they were designed for. The newer transmissions are designed for ATF mainly to increase fuel economy. The newer transmissions commonly use fiber lined blocker rings in the sycro's that are ATF use only. I would speculate that some people put ATF in muncie's to speed up the shifting, ATF has less lubricity and or to find that last tenth of a second ET due to less drag.

Tom

 

[fabio]

I've used atf in my 2 stroke gearboxes for yrs. My buddy runs it in his banshee that makes 3x the power it had stock. Now would I run it in my muncie? NO, I'll just stick with my regular gear oil that's worked fine for yrs.

 

[5speeds]

No, you don't have stupid on your forehead. However anyone that makes a silly rule in regards to what type of lube a transmission uses should be based on the alloy of a case.... yes... big stupid on forehead for him.

Basically its what the box is designed around. Clearances are set to run certain viscosities and if you alter the viscosities you may run into leakage and seizing issues.

Its quite common to see people run ATF in racing applications to gain more rear wheel horsepower. Running ATF will usually wear out shift forks in Muncies more than anything and create front leaks.

 

[manveru]

for what its worth, when my college automotive instrutor raced(gasser years) he would run atf with a bottle of stp in his transmissions, but i think he regularly rebuilt them for consistency

 

[Bow_Tied]

No, you don't have stupid on your forehead. However anyone that makes a silly rule in regards to what type of lube a transmission uses should be based on the alloy of a case.... yes... big stupid on forehead for him.

Basically its what the box is designed around. Clearances are set to run certain viscosities and if you alter the viscosities you may run into leakage and seizing issues.

Its quite common to see people run ATF in racing applications to gain more rear wheel horsepower. Running ATF will usually wear out shift forks in Muncies more than anything and create front leaks.

That makes all kinds of sense. I am not a transmission designer, but I studied gears and transmission design in college engineering. The type of fluid and the viscosity are critical for reliable operation over the designed lifespan. The primary use of a lube is usually cooling - reducing the friction reduces the heat - stops wear, stops seizing of bearings & galling of metals etc.

There are tons of oils that you could run in a muncie... if those oil's properties differ from OE spec, you can expect a change in operation efficiency, change in life span, etc. Why would anyone do this? Well, maybe those changes are an accetable trade-off for increased shift speed or reduction is parasitic drag. The muncie was designed for mulitple applications of street vehicle, other applications may differ of course and simply be aware of that.

For my Chevelle, I will stick with OE spec oil :yes:

 

[bparrishlvx]

I love this forum! Thanks for all your responses and they have obviously helped me determine which gear oil I will use. Do I need to be concerned with getting all of ATF out of the tranny due to cross contanimation of oils or is it not a big deal. I imagine letting it drain out for a couple days should do the trick as it is out of the car so it is easy to do.

Thanks again everyone. :thumbsup:

 

[animal69]

I would tear the tranny apart and check for damage done by running the wrong lube. I never would have bought it after hearing that he ran ATF in it.

 

[Neal Wright]

I don't know if it's any relavance ... but it seemed factory trannies started going to ATF, as the GL4 lube was replaced with GL5? Might just be my imagination?
Neal

 

[JJ'65]

My guess is that it won't hurt anything to use ATF in a manual trans. It seems like the oil is for cooling, cleaning, and friction reduction. If I recall correctly the Muncie has spiral tooth configuration, and not hypoid gear form. I think regular gears are designed to provide rolling contact between the gear teeth as compared to hypoid gears with some sliding contact. So the axle gears need extreme pressure resistance characteristics that the transmission gears could do without.

An aircraft engine (Allison/Rolls Royce T-56 series) I'm familiar with uses the same turbine oil for the gearbox as for the engine lubrication. Same reservoir and oil cooler. 55 psi to the engine bearings and ~170 psi to the gearbox. The reduction gear train used to transmit power to a propeller is a combination of straight-cut spur gears and a planetary gear assembly. THe engine uses ball and roller anti-friction bearings. The same oil is used in an air turbine motor on the airplane. It spins around 70,000 rpm. Engine spins around 13,000 rpm. Gearbox transmits as much as 4,300 shaft horsepower

The turbine oil (MIL 23699) is synthetic and a rather thin consistency, not much more viscous than ATF.

One reason the company specifed 90 wt gear oil in the transmission is probably noise control. Maybe also just to be same as axle lube, and maybe to make sealing less challenging.

In any case, I'd follow the manufacturer's recomenndations

My $0.02

 

[[email protected]]

do a search theres lots of posts about using gl-4 on the old school trannys and who to get it from
Michael

 

[DZAUTO]

My guess is that it won't hurt anything to use ATF in a manual trans. It seems like the oil is for cooling, cleaning, and friction reduction. If I recall correctly the Muncie has spiral tooth configuration, and not hypoid gear form. I think regular gears are designed to provide rolling contact between the gear teeth as compared to hypoid gears with some sliding contact. So the axle gears need extreme pressure resistance characteristics that the transmission gears could do without.

An aircraft engine (Allison/Rolls Royce T-56 series) I'm familiar with uses the same turbine oil for the gearbox as for the engine lubrication. Same reservoir and oil cooler. 55 psi to the engine bearings and ~170 psi to the gearbox. The reduction gear train used to transmit power to a propeller is a combination of straight-cut spur gears and a planetary gear assembly. THe engine uses ball and roller anti-friction bearings. The same oil is used in an air turbine motor on the airplane. It spins around 70,000 rpm. Engine spins around 13,000 rpm. Gearbox transmits as much as 4,300 shaft horsepower

The turbine oil (MIL 23699) is synthetic and a rather thin consistency, not much more viscous than ATF.

One reason the company specifed 90 wt gear oil in the transmission is probably noise control. Maybe also just to be same as axle lube, and maybe to make sealing less challenging.

In any case, I'd follow the manufacturer's recomenndations

My $0.02

Well, I don't know about turbin/jet engines, but in these engines, we use 120w oil. The same oil circulates through the ENTIRE engine, gears in the front case, cylinders and rear case gears.

 

[SWHEATON]

Not trying to start a war here but if the originator of this post wants to run the exact correct GL4 80w-90 lube the muncies are spec'd for by GM and not the GL5 lube sold in most strore these days thsat can supposedly over time attack/corrode the yellow metals of the syncos as stated by the RED LINE/QUAKER STATE/PENNZOIL oil engineers (not me!!!!!) on thsier perspective sites then get CRC'S STA-LUBE GL4-80w-90 from a local NAPA store or at Napa online or just google the sta-lube and you will find other sources.

I believe you can special order it from quaker state and penzoil too but i thnk you have to get it in 5gal buckets and a dry muncie takes approx 1.5qts oil max so that would be a waste but the Sta-Lube comes in qts.

Scott

 

[DZAUTO]

Not trying to start a war here but if the originator of this post wants to run the exact correct GL4 80w-90 lube the muncies are spec'd for by GM and not the GL5 lube sold in most strore these days thsat can supposedly over time attack/corrode the yellow metals of the syncos as stated by the RED LINE/QUAKER STATE/PENNZOIL oil engineers (not me!!!!!) on thsier perspective sites then get CRC'S STA-LUBE GL4-80w-90 from a local NAPA store or at Napa online or just google the sta-lube and you will find other sources.

I believe you can special order it from quaker state and penzoil too but i thnk you have to get it in 5gal buckets and a dry muncie takes approx 1.5qts oil max so that would be a waste but the Sta-Lube comes in qts.

Scott

Agreed.
I've been buying GL-4 in gal jugs from my local friendly NAPA store. :thumbsup:

 

[5speeds]

Have anyone of you builders actually seen Muncie synchro rings corrode? When are you guys going to realize that this BS hype is designed to sell their product? The GL5 stuff is fine....

Tell you what... drop a synchro in a jar of GL5 lube of your choice and stick it on your desk. Drop a ring in the Gl4 and stick that next to it. So lets say that over 10 years the GL5 rings gets a little discolored..... is the sky falling?


"supposedly over time attack/corrode the yellow metals of the syncos as stated by the RED LINE/QUAKER STATE/PENNZOIL oil engineers"

 

[SWHEATON]

HI PAUL,that test wont show the problem from what i was told and here is why.

Here is the situation that supposedly creates the issue with gl5 lube and yellow syncro metals.

If you run gl5 lube in our classic cars that are only used once in a while there are periods of days/wks at a time that the syncors are not being bathed in the gl5 lube which is where the issue is.

Supposedly when you bath the syncros in gl5 lube by driving the car and then expose it to air/moisture after most of the oil runs off durring longer periods of non use (days/wks/months but not every other day or daily use) there are gl5 additives that when left behind on the syncros that can now react chemically with the air/moisture which triggors the oxidation/corrossion process which is the issue in a nut shell from what i was told.

Its not a problem when you bath the syncro in the gl5 lube and never expose any air to it or the trans is in daly or everyother day use. It just durring extended non use periods that it can become an issue.

And there is no way that i can see that the oil mfg's are going to make more money because they say not to use gl5 and use gl4 fr our muncies. Doing that just shifts us from from buying 2qts gl5 lube to 2 qts gl4 lube to fill a dry muucie,there is no additional money to be made from that at all.

PAUL,your killing the messenger (ME/LOL!!!),again,why dont you contact the oil mfg/s through their website(Redline) to ask them why they rec not using gl5 lube in trans with yellow metals to see/hear for yourself what they are saying,have an open mind,i dont really think the oil mfg's are trying to take us for a ride on this one ,gasoline/pas car oil is a different story.

Scott

 

[5speeds]

Actually ...AGAIN.... has anyone ever seen this "theory" happen?

The issue is not about selling a GL4 lube or a GL5 lube, most of the time this issue comes about as a sales pitch towards running synthetics vs non synthetics and what brand of synth fluids to choose over another. Notice how some manuafacturers will not mention the corrosive effects, while others do. The forums if anything have some how magnified this issue.

The Royal Purple Max Gear is a GL5 and GL4 rated Lube. The spec sheet shows GL5. All our race units use this lube for years with absolutely no issues in Muncies, no leak issues, and no wearability issues. As far as MTL RedLIne lube goes, unfortunately that did not work out well for us , causing galling and heat checking of gears, and breaking down ( turning to jelly) in severe use applications. My point is you need to see past the marketing hype sometimes and look at real world situations...

As far as boxes sitting with lube for a long period of time THEORY. The problem you have with that is moisture and moisture contamination in oils..