GL-1 Gear Oil Alternative

Hi Jon,

JDToumanian said:

That is interesting data.... I have learned something new. But I don't think it means that 50wt motor oil or a 50wt "transmission oil" are interchangeable with SAE 80/90 gear oil.... The additive package would be different, with the SAE 90 having viscosity modifiers and extreme pressure additives and the 50wt oils would not.

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That is right, SAE 50 engine oil (meant for an engine) is not functionally the same as SAE 80/90 gear oil. The mineral oil base is, but the additives put into that base are meant to handle vastly different conditions.... For example, engine oils generally run in a much more severe environment than transmission oils. They run much hotter, and have moisture and other impurities added by the combustion process that would never happen in transmissions. It would be a really bad idea to run SAE 80/90 in your engine! But it doesn't follow that it would be a bad idea to run SAE 50 engine oil in your transmission.

I am pretty certain that Shell's "SAE 50 gear oil" is just a yellow metal safe SAE 80/90 gear oil that has been labeled wrongly to facilitate sales to users of Spicer transmissions. I am not thinking fraud, as the Shell SAE 50 probably has additives that are beneficial to Spicer transmissions.

For some reason, Spicer does not want their manual transmissions to use an oil with extreme pressure additives... They state this fact in the oil specs in their civilian owner's manuals.

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Not speaking for Spicer, but the reason they don't want EP additives is the early EP additives were simply sulfur. Sulfur is a very good high pressure lubricant, but when presented with moisture, heat and other environmental conditions, it can form acids that will wipe out the brass in the synchronizers.

And...

There is no need for Extreme Pressure additives in a transmission, because there are no extreme pressures in the bearings, or gears, in a transmission.

Transmissions are pretty tame devices when it comes to their lubrication needs.

Hypoid geared differentials are another thing entirely. The hypoidal gear sets have considerable contact pressure under heavy loads [all that torque available at the axle], and a distinct sliding component when the gear faces mesh with each other. Hypoidal gears need fancy additives to prevent excessive wear during normal operation, and to provide adequate cushion to protect the gears from the indelicacies of the road... [think about what happens to that poor differential gear set when you power your way through a pot hole, and bounce out the other side...]

-Chuck

The best feature about the Chevron 50wt gear oil-

"Extended drain capabilities—Proven field performance for on-highway drain intervals of 500,000 miles and greater."

That equals about 1000 years in the average deuce (500 miles/year- my experience)

I'm still trying to sort all of this out. So am I following this correctly?

The updated lubrication order (LO 9-2320-209-12-1) specifies the gear oil as needing to meet MIL-L-2105. I assume this means any revision of this specification such as MIL-L-2105D. If that is correct I have found that MIL-PRF-2105E has superceded MIL-L-2105D as shown in the following.

MIL-PRF-2105E

I also found a document that discusses many aspects of these specifications and states that SAE J2360 is identical to MIL-PRF-2105E.

Page Title

If I'm reading all of this correctly I think I feel better about purchasing Mystik JT-7 80W-90 since it meets MIL-PRF-2105E & MT-1.

http://docs.mystiklubes.com/msds_pi/20008.pdf

I just picked up two gallons of GL-1 transmission fluid for ford tractor manual transmissions at tractor supply. Hope that is right!

Marlboro said:

I just picked up two gallons of GL-1 transmission fluid for ford tractor manual transmissions at tractor supply. Hope that is right!

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It will work. It isn't the best oil you can buy, but it is a good straight mineral oil that is typical of the oils made when the deuce was designed....

That said, modern oils are so much better than the oils that existed when the deuce was designed that they almost single handedly tripled the useful life of automobiles. Back in the 1960's it was rare for a car to get past 100K miles with much life left in it. Today it is rare for a car not to make it past 200K miles, and pretty common for many cars to break 300K miles.

-Chuck

Seems like everyone has a different opinion or preference for gear oils. Ever read the API classifications for gear lubes? I know some of you think the Deuce tranny is heavy duty. It is not a heavy-duty transmission. Deuce transmissions are light duty. The mineral oil call is most likely Uncle Sam’s idea to keep things simple and use the same oil used for other machinery. The 3053 is not as heavy duty as the 3152, 3153 or the 3052. Some of you can check that by comparing the gears. 1st gear in all of them shares the same 45-tooth MS gear. Take a good look the 3053 gear, it is narrower. To be exact it is 4 ounces lighter weight. All gears in the 3053 are narrower than the others but all have the same shaft and case length. GL-1 is a light duty oil made for light duty gearboxes without synchronizers.
You will not find much GL-1 around my part of the country. In fact it is getting down right difficult to get GL-4.
Most people have a manual transmission from the land of many chopsticks! They all seem to use a particular type of synthetic. GL 1&4 has become obsolete.

RECOMMENDED LUBRICANTS
(From Spicer Manual not you’re TM)
The lubricants listed below are recommended, in order of preference, for use in ALL Spicer mechanical transmissions auxiliaries and transfer cases.

Temperature Grade Type
Above 0 F. SAE 30,40 or 50 Heavy Duty Engine oil Meeting MIL-L-46152
Below 0 F. SAE 30 Oils meeting MIL-L-2104B or
MIL-L-45199 Are Also Acceptable

Above 0 F. SAE 90 Straight Mineral Gear Oil – Type R & O
Below 0 F. SAE 80



API classification subdivides all transmission oils into 6 classes:

API GL-1, oils for light conditions. They consist of base oils without additives. Sometimes they contain small amounts of antioxidizing additives, corrosion inhibitors, depresants and antifoam additives. API GL-1 oils are designed for spiral-bevel, worm gears and manual transmissions without synchronizers in trucks and farming machines.
API GL-2, oils for moderate conditions. They contain antiwear additives and are designed for worm gears. Recommended for proper lubrication of tractor and farming machine transmissions.
API GL-3, oils for moderate conditions. Contain up to 2.7% antiwear additives. Designed for lubricating bevel and other gears of truck transmissions. Not recommended for hypoid gears.
API GL-4, oils for various conditions - light to heavy. They contain up to 4.0% effective antiscuffing additives. Designed for bevel and hypoid gears which have small displacement of axes, the gearboxes of trucks, and axle units. Recommended for non-synchronized gearboxes of US trucks, tractors and buses and for main and other gears of all vehicles. These oils are basic for synchronized gearboxes, especially in Europe.
API GL-5, oils for severe conditions. They contain up to 6.5% effective antiscuffing additives. The general application of oils in this class are for hypoid gears having significant displacement of axes. They are recommended as universal oils to all other units of mechanical transmission (except gearboxes). Oils in this class, which have special approval of vehicle manufacturers, can be used in synchronized manual gearboxes only. API GL-5 oils can be used in limited slip differentials if they correspond to the requirements of specification MIL-L-2105D or ZF TE-ML-05. In this case the designation of class will be another, for example API GL-5+ or API GL-5 LS.
API GL-6, oils for very heavy conditions (high speeds of sliding and significant shock loadings). They contain up to 10% high performance antiscuffing additives. They are designed for hypoid gears with significant displacement of axes. Class API GL-6 is not applied any more as it is considered that class API GL-5 well enough meets the most severe requirements.

I have been getting the Ford Tractor Manual Transmission Oil from Tractor Supply. It is VERY cheap at $12.00 for two gallons.

Tagged for good info. Getting ready to replace my fluids and was curious if newer oils were any better than what the TM's recomended 40 years ago.

How anyone can justify not using GL-5/MT-1 all around is truly amazing. Can *ANYONE* show me these rotted out synchro's that are supposed to dissolve when in MT-1 spec lube? A picture is all I ask.

Paul the MT-1 is so the synchro's do not rott or dissolve. MT-1 or "yellow metal safe" are the key things to look for.

That was my point. Anything that likes GL-1 (straight mineral oil) is gonna love GL-5/MT-1.

ALL non-synthetic oils are the same base component. Its just the extra additive packages they toss in for more modern components (tighter clearances, etc).

What's wrong with GL-1? It's worked in these trucks for 50+ years without problems.
1) It's cheaper than GL-5
2) It's what the manual calls for
3) I'm not aware of a problem with running GL-1 in these trans.

paulfarber said:

How anyone can justify not using GL-5/MT-1 all around is truly amazing. Can *ANYONE* show me these rotted out synchro's that are supposed to dissolve when in MT-1 spec lube? A picture is all I ask.

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GL-5 has pressure additives makes the synchros have to work harder.

API Category GL-1 (inactive*) designates the type of service characteristic of manual transmissions operating under such mild conditions of low unit pressures and minimum sliding velocities, that untreated oil may be used satisfactorily. Oxidation and rust inhibitors, defoamers and pour depressants may be used to improve the characteristics of lubricants intended for this service. Friction modifiers and extreme pressure additives shall not be used.

API Category GL-5 designates the type of service characteristic of gears, particularly hypoids in automotive axles under high-speed and/or low-speed, high-torque conditions. Lubricants qualified under U.S. Military specification MIL-L-2105D (formerly MIL-L-2015C), MIL-PRF-2105E and SAE J2360 satisfy the requirements of the API GL-5 service designation.

API Category MT-1 designates lubricants intended for non-synchronized manual transmissions used in buses and heavy-duty trucks. Lubricants meeting API MT-1 provide protection against the combination of thermal degradation, component wear, and oil seal deterioration which is not provided by lubricants meeting only the requirements of API GL-4 and API GL-5.

API Categories GL-1, GL-2, GL-3 and GL-6 were declared inactive by SAE Technical Committee 3 in 1995, even though oils may be marketed with these designations. Similarly, ASTM does not plan to maintain the performance tests associated with these categories, as in a number of cases these tests can no longer be run because parts or test installations are not available.


The reason that GL-1 states that no EP additives were allowed is becuase EP additives are sulpher based, and will attack copper based metal (brass etc). But GL-1 is long dead. The MT-1 spec's EP additives are 'yellow metal' safe. The 'copper strip' test ATSM-130 IIRC rates the 'corrosiveness' of the oil, 1a being best, the higher the number/letter the more acidic the additives are. The myth being that snychros will be eaten by the additives.

My point is SHOW ME A SYNCHRO THAT HAS BEEN EAT UP BY A MODERN GL-5/MT-1 OIL. Take an old, worn out synchro and throw it in a tub of GL-5/MT-1 and get back to me when there is some degradation. I'll wait.

Most EP additives don't get corrosive till 250F+ is reached... even then most are rated at 2a on the test scale, which is between no and very mildly corrosive (discoloration).

You cannot read a 30 year old lube spec and say that modern oils are incompatible. Lubes have gotten BETTER, not worse.

There is no reason not to use a GL-5/MT-1 lube.

So, where is a GL-5/MT-1 oil NOT suitable? I don't know.

I have GL-5/MT-1 in my 42 GPW (tranny and transfer, diffs) and 43 CCKW (tranny and transfer and diffs) and have rebuilt the jeeps tranny and transfer with to correct popping out of gear issues (tranny was to replace a worn input shaft, transfer for an intermediate gear and shift fork) and after 4 years since owning it the synchros were nice a shiny, both units work flawlessly now (after repair).

I heard tell..

that maiden oil works on the bed....

There is no reason not to use a GL-5/MT-1 lube.

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Paul, back when I used Chevron DELO ESI 80w-90 GL-5/MT-1, my transmission became much harder to shift. It failed within 1000 miles, though the failure cannot be traced to the oil change. However as you show in your post above, the MT-1 rating is for NON-SYNCHRONIZED manual transmissions. In my quest for the "ideal" oil, I discovered synthetic oils designed for synchronized manual truck transmissions. Shell DENTAX 50wt, Chevron DELO Synthetic Gear Oil SAE 50, and others. These are oils formulated for exactly our application. My transmission shifts great and runs cooler, and hopefully will live a long life.

The best reason I can think of not to use GL-5 is that Spicer says not to. They say the oil "MUST NOT" contain extreme pressure additives....

Jon

JDToumanian said:

The best reason I can think of not to use GL-5 is that Spicer says not to. They say the oil "MUST NOT" contain extreme pressure additives....

Jon

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So according to Spicer what should we use? Getting ready to change fluids so would like to know.

Hey, here is an idea. How about NAPA GL-1?

uh

After reading on this site for about 5 years, I am still confused on this topic of acceptable deuce transmission lubes. I would like to run the GL5/MT1 stuff from China Mart with a quart or two of Lucas additive stuff (I dont know why, I just do). I have a new to me 1987 M35A2C that I wish to drain and refill the transmission fluid. Is that 80-90W GL5/MT-1 rated stuff from Wally world going to eat my synchros?

JDToumanian said:

Paul, back when I used Chevron DELO ESI 80w-90 GL-5/MT-1, my transmission became much harder to shift. It failed within 1000 miles, though the failure cannot be traced to the oil change. However as you show in your post above, the MT-1 rating is for NON-SYNCHRONIZED manual transmissions. In my quest for the "ideal" oil, I discovered synthetic oils designed for synchronized manual truck transmissions. Shell DENTAX 50wt, Chevron DELO Synthetic Gear Oil SAE 50, and others. These are oils formulated for exactly our application. My transmission shifts great and runs cooler, and hopefully will live a long life.

The best reason I can think of not to use GL-5 is that Spicer says not to. They say the oil "MUST NOT" contain extreme pressure additives....

Jon

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I am a bit confused.. many wandering points.

What exactly failed? A seal? A gear? A shaft? The case cracked?

"The failure cannot be traced to the oil change"?!?!?!?!?

Synchronized trannys have the brass snychros that the MT-1 spec protects. I have GL-5/MT-1 in both a synchro'd (my 42 Ford GPW) and un-synchro's (my 43 CCKW) tranny. Nothing has failed and no significant changes were noted.

If you want to use GL-1 great, but its not worth the effort to find when GL-5/MT-1 is on every shelf of every store, and does not do the damage people are claiming. The best we get are stories.

The *ONLY* time I get fussy with oil is on wet clutches (aka motorcycles). My 'zuki cannot have 'energy saving' oils.. the additives slip the clutch to much (its actually TO slippery). Other than that I used the GL-5/MT-1 in the final drive.

No one has come up with anything remotely credible to change my mind. If your tranny blowed up because of GL-5/MT-1 please post!