Transmission gear oil

1945 - 196*, Willys CJ series, questions, discussions, regarding anything related to the post war jeep.®
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Paul Randazzo
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Transmission gear oil

Post by Paul Randazzo » Sat Mar 11, 2017 1:25 pm

Hello all!
I have rebuilt several T84 and T90 transmissions and I am having trouble locating GL4 gear oil. I have been in touch with some suppliers and they say only GL5 is available and of course synthetic blend or full synthetic. GL5 and GL4/5 are really not good for any synchromesh transmission because of the effects on the "yellow" metals inside the gear box. The sulfur additives destroy the synchros and thrust washers (yellow metals). I have tried synthetic oil and it leaked from everywhere and I know of others who have experienced the same problem. I found this Stay-lube product made by CRC on Amazon but it originates from China (that's not ok with me).
https://www.amazon.com/Sta-Lube-SL24239 ... 4+gear+oil
Anywhere I go they seem to have no idea what I'm talking about. They say no one ever asks this question, just-I need gear oil
Does anyone have any idea where I can get the GL4 only rated oil? Preferably 85/90, 80/90 is good too.
Thanks guys,
Paul
Last edited by Paul Randazzo on Sat Mar 11, 2017 2:32 pm, edited 1 time in total.
1960 Hotchkiss M201
1951 JDF 1/4 ton
Fleet Automotive Tech ret
Chief Veh Maint Mech Museum of American Armor Old Bethpage NY


Joe Gopan
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Re: Transmission gear oil

Post by Joe Gopan » Sat Mar 11, 2017 1:32 pm

There are a lot of comments on the use of GL-5, some are unfounded. Best to call Customer Service of the brands you are interested in. Some brands of GL-5 are compatible with yellow metals.
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Paul Randazzo
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Re: Transmission gear oil

Post by Paul Randazzo » Sat Mar 11, 2017 2:35 pm

Thanks Ben. What have you been using?
1960 Hotchkiss M201
1951 JDF 1/4 ton
Fleet Automotive Tech ret
Chief Veh Maint Mech Museum of American Armor Old Bethpage NY

Joe Gopan
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Re: Transmission gear oil

Post by Joe Gopan » Sat Mar 11, 2017 3:00 pm

Been using Lubriplate #90 for 33 years in the CCKW, and used EXXON SAE 80W-90 since 1975 in my M-38A1 and MB It was GL5 Rated, have around 70,000 on the 100% New Build M-38A1 with about the last 5000 miles on EXXON-Mobil GL-5. MB is on it's 46th year of trouble free T-84 function, no jumping out of gear either, same for M-38A1.
Reason I use the Lubriplate #90 only in the CCKW is the straight cut gears and the high temperatures the Gearboxes run at.
Lubriplate is expensive, over $125.00 for 5 Gal Pail (35Lb.) but worth it to me in my pet CCKW.
I probably should have used surplus GI Issue GO-90 over the years and saved some bucks. There was no concern with GI GO-90 in Jeeps during the 50's and later and it was specified for M-38/M-38A1, M-37, the REO 6X6 and the 5 Ton 6X6. All ad yellow brass in their gearboxes.
Just because I use the GL-5 in my vehicles is no reason to not question my choice.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

Paul Randazzo
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Re: Transmission gear oil

Post by Paul Randazzo » Sat Mar 11, 2017 4:20 pm

Funny the differences people experience. I'm aware of the GL1 and also saw Penzoil GL3 too. I'm sure their good too. After all of the responses of readers on forums I've gravitated to the experienced responses here on the G with respect because we're all driving vehicles from the same era and intended design of the day. You have to take some responses from outside the G with a grain of salt. I've found most from there are inexperienced users that don't have a real clue about what goes on inside a gear box much less a synchromesh transmission. As for now I'll stick with the GL4/5 oil and monitor it's condition.
Paul
1960 Hotchkiss M201
1951 JDF 1/4 ton
Fleet Automotive Tech ret
Chief Veh Maint Mech Museum of American Armor Old Bethpage NY

Joe Gopan
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Re: Transmission gear oil

Post by Joe Gopan » Sat Mar 11, 2017 4:25 pm

I have experienced hardly a trace of brass(and bronze) from my M-38A1(T-90) and MB (T-84) and their transfers over the years. They get drained every 4-5 years now. Good Jeep PM and driving habits help some also.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

Paul Randazzo
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Re: Transmission gear oil

Post by Paul Randazzo » Sat Mar 11, 2017 5:07 pm

Rodger that
1960 Hotchkiss M201
1951 JDF 1/4 ton
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Chief Veh Maint Mech Museum of American Armor Old Bethpage NY

Paul Randazzo
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Re: Transmission gear oil

Post by Paul Randazzo » Sun Mar 12, 2017 8:58 am

1960 Hotchkiss M201
1951 JDF 1/4 ton
Fleet Automotive Tech ret
Chief Veh Maint Mech Museum of American Armor Old Bethpage NY

Rus Curtis
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Re: Transmission gear oil

Post by Rus Curtis » Mon Mar 13, 2017 8:29 am

A lot of discussion on other forums like the 2A and 3B message boards. The biggest issue is simply the additive for the hypoid gears. The additive for GL-4 is the same as GL-5 but not as much and therefore not destructive for the softer yellow metal.

There are manufacturer sources that explain the additives and learning will help understand what is safe and what should be avoided. As mentioned, there are some oils that state "Safe For Yellow Metals" and could be used (including synthetics). Be careful though as not all are the same.

I ordered Sta Lube GL-4 from NAPA since it works for me.
Rus Curtis
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Paul Randazzo
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Re: Transmission gear oil

Post by Paul Randazzo » Mon Mar 13, 2017 9:13 am

Hi Ron,
I'm aware of the "safe for yellow metals" statements on some of the GL5 products and the reduced sulfur content in the GL4 and GL4/5 oils. I have been on the CJ2A & 3A forums. I even posted on this site in the MB & GPW forum. At the end of the day we're all coming up with the same conclusions. I know they're all not the same and the full synthetic & synthetic blends are another story. I used Amzoil many years ago on my CJ5 with a T90 figuring it would be good. My friends were using it in their circle track stock car with great results. Holy Cow it leaked like a sieve from everywhere. I drained and flushed it and put in SAE 90 GL4 like it called for and the leaks stopped and there was never any "yellow glitter" in the oil. I've heard similar stories of old units that preceded the synthetic age with the same problem. Like I said in my other posting, The Jeep only weighs a bit over 2000 lbs., has low gearing making it easy to get moving even when loaded. It only gets driven about 1500 miles a year, the problem exists only when driving not parked and I will monitor the condition of the oil. If I start to see "yellow glitter" in the oil I'll try something else. Thanks for your input!
Paul
1960 Hotchkiss M201
1951 JDF 1/4 ton
Fleet Automotive Tech ret
Chief Veh Maint Mech Museum of American Armor Old Bethpage NY

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ghiltgen
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Re: Transmission gear oil

Post by ghiltgen » Sun Apr 09, 2017 8:33 am

Late response but better late than never. Portral press posted a series of 5 youtube videos on the T84 transmission. The guy doing the rebuild has a lot of experience with early jeep transmissions. He said he uses only the GL1 fluid which has no additives. As mentioned earlier, the additives turn into sulfuric acid and cause premature failure of the brass components in the tranny. The 90 weight GL1 is widely available. Tractor supply carries it as Ford tractor transmission oil. I use it in my 1948 CJ (T90) with no issues.
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Re: Transmission gear oil

Post by Joe Gopan » Sun Apr 09, 2017 9:04 am

I have never lost a Gearbox in any of the T-90's (and T-84) equipped Jeeps used as daily drivers. My M-38A1 is pushing 70,000 miles since 1975 and the MB-has been serving me since 71, no yellow Gear Oil chips yet. Neither have any noise or jumping out of 2nd habits.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

Paul Randazzo
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Posts: 95
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Re: Transmission gear oil

Post by Paul Randazzo » Sun Apr 09, 2017 11:52 am

Late responces are great. I did consider the GL1 oil however I did find GL4 85/90 made by Coastal.
1960 Hotchkiss M201
1951 JDF 1/4 ton
Fleet Automotive Tech ret
Chief Veh Maint Mech Museum of American Armor Old Bethpage NY


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