M37 Fluids

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New member
I have recently been given a 1961 M37 that belonged to my grandfather, it has sat for about five years but with two new batteries, some new fuel and oil lines and a fresh oil change I have been able to get it running. The next thing I want to do is replace the fluids in the:

- Transmission
- Transfer case
- Front and Rear Diffs
- Winch

What oils are y'all using in each of them and how much do they hold?

Thanks in advance!


North Lake, WI
Go to the Technical Manual section on this site and download the TM's for your truck. You will find the answers to your questions.


John Mc

New member
Monkton, VT
Lubricants have changed dramatically (improved) since the tech manuals came out. There seems to be a debate between the originaly recommended lubes and more modern ones. I have 10W-30 non-synthetic in my engine and an 80 or 90 weight gear oil in the transmission, be cause that is what was in it when I bought it. I'm debating switching to synthetics when I rebuild the transmission and change the oil in the engine. What I'm thinking of is Amsoil Z Rod 10W-30 (something specially formulated for classic vehicles - includes a heavy dose of zinc) and Amsoil SAE 50 Long-life Synthetic Transmission Oil (supposedly works much better in colder conditions, while still providing superior lubrication at warmer temps). I've still not decided if I will go this way, but leaning strongly toward it.

Part of the debate centers around sticking with the original specified fluids vs taking advantage of modern improvements in lube technology. Another point of contention is that "synthetic lubes cause seals to leak" (supposedly). THere are two factors to this rumor: (1) gunk builds up around the seals over time, actually heping the seal to do its job, and (2) synthetic lubes shrink seals, or at least fail to cause them to swell the way non-sythetics do. In response to #1, I'll be making the switch after a transmission rebuild. There will be no "gunk". If it leaks from the start, I guess I've doen a poor job on the rebuild. As far as #2: it's true that early synthetics had this problem a bit - they did not swell the seals the way traditional lubes did. However, the spec for modern synthetics requires that they include seal conditioner additives.

Some people have had very good luck using synthetics, some swear they are a problem. If I end up going that way, I guess I'll find out for myself. If I do make the swap, I'll try to remember to share my experience here. I'd love to hear from folks who have actually tried both.
Last edited:


Temple, NH
Hi zalooney

Here is a link to the manuals https://www.steelsoldiers.com/threads/tm-9-2320-212-10-m37-series-operator-manual.99577/

Being apparently new to the truck and maybe new to the wonderful world of MV'S first welcome to the fun. M37 s are not fast but they will go just about anywhere.

Now to lubrication John Mc response should give you a good starting point.

One of the problems is that the military like most manufacturers have there own proprietary names and numbers listed in the manuals that the local auto parts store will not understand and may or may not give you the correct lubricates.

Cheers Phil


New member
Thanks for the input guys! The TMs show to 90w gear oil in the entire drive line (for temps above 32) and four gallons should do it all with a little left over. So now I need to find somewhere that keep 4 gallons of GL-4 gear oil in stock!


Active member
Mesa, AZ
By the time of the RVN experience the 9-2320-212-10,20 and LO series of pubs were issued Korean pubs combine elements of today's -10 and -20 manuals in one book T%M9-8030. These pubs will list the capacities of all gear cases and the products that were authorized to fill them at the time of the issue of the pub. As discussed in previous posts better products are available today but the quantities used will be the same.


Well-known member
Steel Soldiers Supporter
Edmonton, Canada
Engine oil filter type dictates whether detergent or non-detergent oils should be used. Modern fluids don't mean they are better so getting my head around fluid selection for the 1956 M135 took some research.

Here's a bit of reading and a link that helped with decisions.

""""""""When early engines (prior to 1954) were new, oil filters were an accessory item and non-detergent oil was the type of oil used. Original, unrestored engines have most likely been run on non-detergent oil. If you are running an early unrestored engine that is not spotlessly clean internally, it is imperative to continue to run it on non-detergent oil. Otherwise there is the risk of damage to the engine.

Non-detergent oil was used before oil filters became standard equipment. This type of oil would "stick" contaminants to the sidewalls and valleys of the engine to prevent dirty oil from damaging bearing surfaces. Engines that have been run on non-detergent oil for many years will have a thick "sludge" buildup. Sludge will appear to be oil that has turned to gelatin except that it will be very black with contaminants.

Using detergent oil in an engine that had been running non-detergent oil would allow these contaminants to be released to flow through the engine. This could result in serious damage to the rod, main and cam bearings as well as other engine components such as lifters and plugging of oil lines.""""""""


Senior Chief/Moderator
Super Moderator
Steel Soldiers Supporter
Cheyenne, WY
I have a couple cases of straight 30 weight back from the early 80's that I have been running in my engine. I have 90 weight in all the drive line. The steering gear has john deere cornhead grease (which I am not sure I like). My winch will have 140 weight. My steering gear will probably get switched to that at some point.
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