GL-1 Gear Oil Alternative

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mikew

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I don't like GL-1 gear oil and wanted something "better" in my transfer case and transmission.

GL-1 is hard to find, and finding one with a corrosion inhibitor is even harder!

So I called my local HD truck driveline shop, Blumenthal's. They gave me the tech support phone number to Meritor, Rockwell's new name.

I spoke with Meritor for awhile and this is what I learned.

They recommend GL-1 with a corrosion inhibitor package, SAE 50W synthetic, or...

SAE 30W, 40W or 50W motor oil that meets the CD spec.

I asked, "You mean like 30W Rottella T diesel oil?" he said yep, you'll love it!

Here's the lubrication document that covers all Meritor/Rockwell products and it includes T-136 transfer case info.

http://www.meritorhvs.com/MeritorHVS_Documents/MM1.PDF

We did not discuss the axels, but from this document they recommend a GL-5 lubricant for double reduction axles.

If anyone knows the Rockwell axles part numbers for the Deuce I'd like to confirm they are listed as ones that use GL-5 before I switch.

I'm off to Tractor Supply to get a 5 gal bucket of Rottella T to refill my transfer case that is sporting a brand new sprag in it!

Mike W
 

Snarky

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You can put what ever you want in the transfer case but the spicer transmissions and their yellow metal synchros get very angry if you don't put GL-1 in them, or something else that is yellow metal safe in them. The detergents and additives do unfortunate things to those pricey synchros, ask me how I know...
 

mikew

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edmond, ok
That's the thing, the transfer case has yellow metal syncros too. Meritor specifically warns not to use a GL-5 gear lube because it will eat yellow metal.

Motor oil doesn't have the sulfur based additives that attack copper alloys but it does have lots of corrosion inhibitors.

Many manual transmissions that have bronze syncros call for 30W motor oil.

So what results did you have with motor oil in a Deuce transmission that went bad? What oil did you use?

I'm feeling pretty darn safe about this, I'll report back with results.... in a few years!

Mike W
 
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wdbtchr

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There is a thread on here from a couple of years ago n this very subject. There is a GL5 that is compatable with yellow metal, but I don't recall the details and don't have time to do a search for it right now.
 

WillWagner

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This has been covered many, MANY times. A search will yield oodles of hits. In a nutshell, read the label, if it is yellow metal compatable, you are good to go. IDK if i'd put 30wt motor oil in a vehicle that has the 26k capabilities, it might be a tad much for the lube.
 

Jake0147

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MT-1 is the additional specification often tacked onto GL-5 that people say makes it backwards compatible. All I have ever found in that specification was specifically for non-synchronized boxes. Besides, if it were a backwards compatibility rating, why are certain GL-1 applications required to have GL-1 plus MT-1? It is inhibited a bit, but fully. I can't see filling my oil with stuff that my transmission can't make use of the benefits of, but is extremely susceptible to the side effects of, only to add more additives to counteract the additives I don't need... Oh well, who knows. I don't. I'll pose this question though, if more "improvers" are always better, what happened to GL-6?

Napa has GL-1, usually in stock. That's what's called out in the TMs. Five gallon pails are the best value. 65-205 fits the TM recommendations, but it's dropped out of fancy for OTR trucks, it's not on the shelf there any more. The OEM recommendations from Spicer were for a 50 weight. If you're looking for a modernized upgrade to include R&O you can find that at the truck shops since (50W plus MT-1) in main stream use.
 
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LowTech

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Steel Soldiers Supporter
Just found this on a diff forum, it was an old tractor forum and they were talking about GL-1 for tractor gearboxs.
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A couple of years ago, there was a really informative post on another board by an oil company rep. He worked for Schaefer. I'm placing his comments here for everyone. I'm also including a link to the original thread.

==================================================================================================

I hope y'all don't mind me jumping in on this discussion. I came across it quite by chance while searching for information on a particular brand of cornhead grease (my searching took me to this thread wherein cornhead grease had been mentioned).

I noticed that you are discussing GL-1 vs. GL-5 gear oils for use in older equipment.

I work with Schaeffer Mfg. Co. out of St. Louis, MO. Schaeffer is the olders lubricant maker in America (established in 1839) and a leader in the field of specialized lubricants.

The API (American Petroleum Institutes) GL-1 service designation denotes a lubricant that is intended for manual transmissions operating under such mild conditions that straight petroleum or refined petroleum may be used satisfactorily (i.e. without the use of friction modifiers or extreme pressure additives). On the other hand, the API GL-5 service designation denotes a lubricant that is intended for gears--particularly hypoid gears--in axles operating under various combinations of high-speed shock loads and low-speed, high-torque conditions.

Many lubricants that have GL-5 ratings can be used in GL-1 applications (depending upon their additive chemistries)...much in the same way that an API CH-4 diesel oil can be used in equipment that originally called for CD or CE diesel oil (i.e. the newer spec is backward compatible with the older spec and does everything the older spec required...and then some).

The problem is that some EP (extreme pressure) additives contain active sulfur. Active sulfur is very corrosive to yellow metals (like copper and bronze). However, the latest generation of EP additives do not contain active sulfur and are not corrosive to yellow metals.

Whether or not a particular lubricant is corrosive to yellow metals is determined by testing conducted by the American Society for the Testing of Materials (ASTM). The ASTM D-130 test (the Copper Strip Corrosion Test) evaluates a lubricants compatibility with yellow metals. A lubricant that shows no corrosive activity at all is given a "1a" rating.

Schaeffer Mfg. Co. offers a line of specialized gear lubricants that are GL-5 rated and have a "1a" rating in the ASTM D-130. This means that they will provide valuable extreme pressure protection that is not offered by a GL-1 product and yet still be compatible with the yellow metal components. Morever, the Schaeffer gear oils contain "moly" (a friction modifier that plates the steel surfaces, giving them an even smoother finish, and withstands 500,000 psi of pressure). Further blended into the products are tackifier agents, demulsifiers, defoamers and seal conditions. Moreover, the EP additive chemistry we employ provides our gear oils with a 60% increase in load carrying ability when compared to conventional lubricants (as show in the 4-Ball EP Weld Point Test).

Where I live (in Kentucky) Schaeffer's reputation in coal mines is legendary. If you would like more information on our specialized gear lubricants, please don't hesitate to contact me.

Johnnypopper gear oil thread -(140 Weight Oil - Invision Power Board)

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The rest of the thread had some other bits of info from the same individual as well, . . . good reading.
 

m-35tom

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as many will recall, i have been using 40wt in trans and transfer for many years. easier shifting, better milage. the rears are hypoid, so require a different oil.
 

67X

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I personally wouldnt use GL-1 from the sounds of it, it seems to work. But how well? Everything i have read states that its for use in light duty trucks..its old out of date in my opinion. I just dont feel comfortable running it...look at this article the key standard being the SAE J2360 meets and exceeds GL-5 and conforms to MT-1 and MIL-PRF-2105E
I am going to use this "White Paper" article to make my selection.

http://www.syntheticwarehouse.com/br...lube_study.pdf

Adam

1971 AM General M35A2
1967 Plymouth GTX
 

Westex

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as many will recall, i have been using 40wt in trans and transfer for many years. easier shifting, better milage. the rears are hypoid, so require a different oil.
Sir, can you specify what you mean my "40wt" ; is this engine oil; is this trans lube; GL?. Knowing your knowledge of these gear cases, I think I'll follow.....
 

stumps

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Hi Westex,

It is simple, if the SAE is less than or equal to 70, it is motor oil. If the SAE is greater than 70 it is gear oil.

The viscosity ranges of motor oils, and gear oils overlap. Here is a table that will show that:

Motor oils
SAE 10W - 41/6 cST
SAE 20W - 71/8.5 cST
SAE 30 - 114/11.2 cST
SAE 40 - 173/14.5 cST
SAE 50 - 270/19.5 cST

Gear Oils
SAE 75 - 47/7.0 cST
SAE 80 - 69/8.0 cST
SAE 90 - 285/20.5 cST
SAE 140 - 725/34.0 cST
SAE 250 - 1220/47.0 cST

The viscosity values are shown at 90F/210F, and are in centiStokes. The values come from Machinery's Handbook #23.

Notice that the viscosities for SAE 50 motor oil, and SAE 90 gear oil are almost exactly the same.

-Chuck
 

mikew

Member
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Location
edmond, ok
When I started this post the point I was trying to make was that, while GL-1 spec gear oil is a fine lubricant, it was chosen because of availability in the supply line and a good choice at that time.

Move forward a few decades and there are newer spec oils with improved properties. Specifically, high speed use (I suspect most of us spend more time trying to drive 58mph down the freeway than hauling loads cross country) and GL-1 lacks a lot of corrosion control (due to water not "yellow metal") that most modern oils have.

I'm still doing my research, but the CD spec straight weight "diesel" motor oil that Rockwell recommended to me will most likely be the way I'll go in the transmission and transfer case, GL-5 for the axles. If money was no object I'd use fully synthetic, but my bank account isn't up to that!

Mike W

Mike W
 

mikew

Member
454
6
18
Location
edmond, ok
There is another thread going regarding transmission oil, and it points out that the current Lubrication Order doesn't specify GL-1 it says use MIL-L-2105 80w/90.

Castrol EPX gear oils are MIL-L-2105 spec, I'm sure many others are too.

So even the military is discontinuing GL-1.

Mike W
 

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jwaller

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I've been using castrol syntech 80-90 for about 4 years now and it has an MT-1 rating and is GL5. I've seen no problems in any of the axles, xcase, or transmission.

the trans and xcase do shift much easier and smoother esp at near freezing temps with the syntech. I wanted to use mobil 1 but it was 3x the $.
 

JDToumanian

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Phelan, CA
Notice that the viscosities for SAE 50 motor oil, and SAE 90 gear oil are almost exactly the same.
Chuck-

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.

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. My deuce transmission's 5th gear failed recently.... When I replace it I have decided to use this:

https://cglapps.chevron.com/msdspds/PDSDetailPage.aspx?docDataId=307252&docFormat=PDF

....Or an equivalent like Shell Dentax S, but I have a Chevron Industrial Lubricants distributor right down the street from me....

Jon
 
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