Trans Oil Overview 3053A

After reading all the posts and Tm's on Deuce trans oil, I was so confused, and had not really come to any one conclusion on what to use. I did however decide that GL-1 is ancient at best, and there had to be something better.

I've searched the net, and found a couple JP magazine tech articles that state the 3053 uses 80/90, never mentioning a thing about yellow metals, or synchros safe. I embarked on my week long mission, to find the RIGHT oil.

I started calling every drive train supply house that I've dealt with in the past, and most have forwarded me to the 50 WT. synthetic used in otr trucks, now I was confused of course because there are posts saying use 50 Wt. engine oil, alas we're those posts wrong? because I have not been able to find 50 wt. engine oil.

I have a good friend that works for my local NAPA, this isn't you're rinky dink NAPA, they have small engine supplies to heavy truck supplies, and they've allways gotten me out of weird part jams, He let me spend a few hours looking over their lube spec books, and eyeing up their inventory, all of my looking and calling boiled down to what I am confident in saying is the correct replacement for GL-1.

I have to say that the earlier posts stating the use of 50 Wt. Synthetic trans oil
in the 3053 spicer would be correct, of course don't take my word for it, a pic is worth a thousand words.


I have changed both trans and T-case with this oil, and have noted much better shifting, and no leaks or seepage other than normal. Good Luck

Why not use GL-1? It is available .

Others have reported seized bushings in second gear(iirc), using synthetics. I would not use it based on others experiences.


I think it has been said that Spicer actually specified the use of 30 wt oil in the trans, originally.

In civilian trucks of the 1970 vintage, Spicer did spec 50 wt. motor oil. I learned it the hard way, of course. JT

doghead said:

Why not use GL-1? It is available .

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You can spend alot of time and money (synthetics aren't cheap) trying to find a "better" oil when these things have been running for 50 years with good old GL-1 in them.

Some people say GL-1 is hard to find but my local Co-op keeps a pallet of it on hand. Mainly because lots of old tractors use GL-1.

While I have to say yes they've been running on GL-1 for years, but I wanted to use an improved product, we've come a long way since whale oil.

I was trying to obtain a more readily available( to me ) product , that had better qualities, out of my search I was only able to find 1 gallon of GL-1 that looked like it was recovered from the Titanic, I had seen it in Tractor Supply, but no more, was told by a TC employee that they have pulled it from their shelves, (now that may be just their shelves), but seems all of the TC's in my area have yanked it.

I had gotten tired of the cross eye looks , when asking for GL-1, 90% of the people could not understand the nomenclature , cept for my NAPA connection.

I suppose I'll be the guinea pig for trans failure, allong with a few other folks.

i use a combination of napa 80/90 and lucas, the transmission doesn't even get hot any more... just warm to the touch,

i use lucas in the engine, trans, tcase, all 3 axles,

lucas helps shifting, millage, heat, wear. Lucas also helps
Compressor, Turbo, Injection Pump,

lucas also speeds up oil prime from cold start by 50%.
( w/o anti drain back plates installed )

truckers swear by it,

militarysteel said:

i use a combination of napa 80/90 and lucas, the transmission doesn't even get hot any more... just warm to the touch,

i use lucas in the engine, trans, tcase, all 3 axles,

lucas helps shifting, millage, heat, wear. Lucas also helps
Compressor, Turbo, Injection Pump,

lucas also speeds up oil prime from cold start by 50%.
( w/o anti drain back plates installed )

truckers swear by it,

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I had also looked at the lucas 80/90 for the trans, as it is yellow metal safe, I wasn't able to get it locally, and it was more expensive than the super s 50 wt. that i had gotten.

castrol syntec 75-90 is a proper oil. has MT-1 spec. every single parts store and wally world has it.

How much are you paying for that synthetic oil, locally?

How many miles per year, do you think you'll be driving your truck?

Like Waller i too use the 75-90 syntec. I've put just over 160K in this truck since 1999 with no problems. And countless hours at low speed in the woods. I know mistik makes a MT-1 90W gear oil. I have seen it at autozone. But i've never tried it.

160K miles on an M35a2?

We are talking about deuce transmissions here, aren't we?

I've been running GL-1 for decades without ANY oil related failures. No oil in the world can improve that record. I could never justify the change, obvioulsly I wont' see any better dependability.

Doghead, Yes 160K. It regularly makes a 88 mile round trip.

ken said:

Doghead, Yes 160K. It regularly makes a 88 mile round trip.

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Ken- that is amazing and great. I wish you would start a thread about your truck, and detail your use and maintenance. It would be very interesting to many of us. You may have the ultimate long haul M35A2, and we should know more about it.

markmontana said:

Ken- that is amazing and great. I wish you would start a thread about your truck, and detail your use and maintenance. It would be very interesting to many of us. You may have the ultimate long haul M35A2, and we should know more about it.

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I agree, please start a thread and share your secerts

jwaller said:

castrol syntec 75-90 is a proper oil. has MT-1 spec. every single parts store and wally world has it.

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so, ok I've seen allot of oils 80/90,, 75/90,, 75/140, with a MT-1 spec does that nomencalture tell me that it is in fact synchro safe ( yellow metal safe) ?


I've also seen same oils differ in their Mil spec s- 120 somthing or other, I'd have to look up again in my notes. I hated to start another thread about this, but I've seen allot of differing opinions, and couldn't find anything hardcore on paper to show a direct replacement for GL-1, except for finding my 50 wt. synthetic, stating it's a mineral oil, non extreme pressure oil replacement.

Coal Cracker said:

so, ok I've seen allot of oils 80/90,, 75/90,, 75/140, with a MT-1 spec does that nomencalture tell me that it is in fact synchro safe ( yellow metal safe) ?

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Yes.

Ok, I stand somewhat corrected.,, I guess

I have the 50 wt. synthetic in, like others who are running it, I'll keep posted if there are problems.

Has there been any reports of leaks with the synthetic? It's some slippery stuff and can squeak by seals better than GL-1.