Yet another fluids thread....

[TechnoWeenie]

After reading probably a thousand posts, and dozens of threads, probably hundreds of pages, I'm now more confused than ever, and my head hurts.

I'm making a list of fluids, and in searching, the amount of 'use this, not that' followed by 'Make sure you use that, not this' is making my head hurt.

So far, what I've learned is....

1. Make sure your GO is yellow metal safe, but it doesn't matter because if it's not yellow safe it won't hurt it.
2. Use high zinc oil, except when you don't use high zinc oil because of added wear.
3. Don't use 30W in your transmission, unless you use 30W in your transmission. Also, ALWAYS use 80w90 in the transmission except when you don't use 80w90 because the manufacturer only spec'd 80w90 for the Army and not in other vehicles the transmission was used in.










Is there a general consensus on this now?


Oil isn't critical, so I plan on just getting the 5 gallon jugs of Travellers 15W40 or whatever is on sale.


The other question is GO for trans/TC/Diff.

Is there a reason why I shouldn't be using the travellers (Tractor Supply) 80/90 in everything?

Modern day oils, even the cheapest out there, are 10x better than some of the best oils these things saw in service 60 years ago, so... Is it really that big of a deal?

 

[fleetmech]

You pretty much summed it up: buy whatever you think is best and run it. I also agree that modern fluids are way better than anything from when these rigs were new.

I personally noticed a major decrease in shift quality after changing the trans fluid and running ND30. It was fine in the cold, but on long hot drives it got sticky and slow going through the gears. I dropped that crud quick and went to 90wt regular gear oil. Im not 100% sold, Ill probably go back to hypoid 80-90 next year.

 

[HDN]

I think engine and transmission oil are easy to determine because it's typically spelled out in the lube order. I know my M35A3 takes 15W-40 in both the engine and transmission, so no guessing there.

I forget what GO I'd use, but it would probably be the yellow safe stuff just to be sure.

Grease is probably going to be whatever I'd run in farm machinery, especially the waterproof stuff. I've been pumping grayish-green Tractor Supply stuff into all my fittings. I might pack my wheel bearings with it too, not sure yet.

Brake fluid is going to be DOT5 unless a hydrovac is involved.

Don't forget diesel-friendly antifreeze for the cooling system! That stuff won't bubble and cavitate due to engine vibrations like regular passenger car and truck stuff would!

Shall we get into tire soap, washing detergents, and automotive wax while we're at it?

 

[M37M35]

What I do...

For the engine, Rotella or Mobil-1 15-40w diesel rated oil, whichever happens to be on sale at the time.
They make zink additive for engine oil. I haven't been using it but probably will next oil change.

For the trans/t-case/diffs, any 80/90w GL5 that has an "MT" rating, which is supposed to be yellow metal safe, which I think is most if not all GL5 80/90w made these days.
Second gear gets a little finicky when the trans heats up, so when I get around to it I'm going to add some Lucas oil stabilizer and see if that helps.

 

[Jeepsinker]

Run whatever you want for engine oil. You aren't going to get more than 100k miles out of it before it needs major overhaul anyway. A zinc additive absolutely does help though. It's not just a wear thing, but you'll also notice the engine just runs better, pulls harder, and gets better fuel economy with the zinc additives than without.

For the transmission, the reason you can't get a concensus is because literally every one acts differently due to wear in different amounts on different components. I've used 80/90, 30 wt, 40 wt, and synthetic 75w90. My transmissions stay in like new condition inside. With 80/90 it was just alright, absolutely zero gear scratches ever. With 30 and 40 wt, it did shift smoother generally but yielded about four scratches in three years. The 75w90 runs noticeably cooler at high speeds and I know it protects better, but it doesn't shift as easily. I think because it is slicker and the synchros don't grab like they should. I generally will scratch at least once every time I drive it now unless I use the clutch. And yes it is yellow metal safe. Not all synthetic is detrimental to brass.