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Discussion Starter · #1 ·
Is anyone using anything other than +4 in their t case? reason I ask is I seem to remember having read somewhere that people were using 10 weight oil for greater lubrication.
Thoughts?

Mark
 

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stick with atf. I suppose you could use premium hydraulic fluid like deere hygard low vis or kubotas equivalent. NOT THE JUNK PLACES LIKE TRACTOR SUPPLY SELL THAT TURNS INTOA SOLID AT -10F.
Remember theres an oil pump in there so if you go too thick in a cold climate its gonna fail. Finding a good 208 or 88-93 241 is a tall order these days also. Stick with the atf+4.
 

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Discussion Starter · #3 ·
Yup, it's been known to get cold up here in NW Minnesota.

Mark
 

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Yup, it's been known to get cold up here in NW Minnesota.

Mark
When I was still in high school I worked summers for a company refacing the military housing on Grand Forks AFB. Some of the local workers and I ( I am from WA) went to some 4th of July festival in Red Lake Falls back in about 86 I think. Good times. Beautiful country up there in NW MN. My Dad's family is from Ada and Halstad.
 
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Discussion Starter · #5 ·
Funny you should mention Red Lake Falls........

Mark
 
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after exploding half a dozen 208's and 241's [ atf fluid ] i switched to 10W motor oil and NEVER looked back and have NOT had a problem since

Note / run what you want or what the "factory" says , but how can the same weight oil with better lubrication not work better than the atf
 
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Note / run what you want or what the "factory" says , but how can the same weight oil with better lubrication not work better than the atf
That is a good question, what is best?

How many planetary gear sets do you know that the factory says to use motor oil?

Here is a excerpt from an SAE study.

A typical planetary gearbox has several load bearing elements which are in relative sliding motion to each other which causes heat to be released. The major sources of friction as well as heat are the meshing teeth between gears (sun/planet, planet/ring), thrust washers, thrust bearings and needle bearings. The lubricant performs the vital function of both lubricating these sliding interfaces and cooling these sources of heat, thereby preventing failure of the gearbox.
Everybody says you need to worry about the chain, I have only seen two 208's destroyed from lack of lube, they both had the planetary gears gone.

I am on the fence on this. The only auto I know that runs a 10 weight oil, is the Army allisons. But I never knew why they switched, from an ATF. It had to be costly, to have all the trucks drained and refilled.
 

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Funny this topic came up since I just did some research on this and on oil in general for my current project so if anyone has conflicting info please poke holes in this since i am going off memory and other peoples forum posts.

Apparently when the NP208 first came out it was specd for motor oil in many applications. One post said his manual called for 10w80. A plausible explanation from a couple different posters was all the manufacturers switched to ATF more for fuel economy reasons than longevity. I think the viscosity is only partially correct.

I was reading up on the properties of ATF and learned dex3 is similar viscosity to a 10w20 or 10w30. This is quite a bit thinner than the 10w80.

I then read up on gear oil and i learned 75w90 is roughly the same thing as 10w40. Why don't they call it 10w40 then? Because they don't want some idiot throwing it in their engine or trans by mistake. A couple of the major differences between gear oil and motor oil is gear oil doesnt have the detergents and depending on the version of gear oil it can be high in sulpher which is bad for brass (synchros) and part of why it is so pungeant.

Really the major difference between the three isnt the thickness but the additives packages.

With that train of thought both motor oil and ATF on the other hand have detergents that gear oil doesnt have or need. But once again the detergents between ATF and motor oil will be different since motor oil is trying to wash carbon off everything whereas ATF doesn't have a carbon problem but is trying to keep belts and clutches clean.

In my opinion I think this narrows down why everyone calls for ATF. It has less unecessary detergents than motor oil, it doesn't have the sulfur some gear oil has and it's high in antifoam agent which is probably where all the chain oiling comments stem from. It's just easier to use a broad stroke and say ATF is safe for the NP208 than it is to sit and nit pick each and every motor oil or gear oil that may or may not work because people only look at the viscosity on motor and gear oil not the specifications. We all know for example that someone is going to put in the wrong gear oil in and freak out because his syncro disintegrated.

To answer the initial question I am marrying a NV4500 to a NP208 and plan on running Redline MT90 (75w90) in both since it is syncro safe. Can't speak to longevity since its not on the road yet. I am mostly doing it so if i have a seal failure i don't have ATF mixing with my manual trans fluid.

TLDR in my opinion manufacturers call for ATF not because its thinner or that you can't use other oils but because it is 'good enough' and they can use blanket statements like 'use any dextron 3 and you will be safe" which you cannot do in the world of motor or gear oils without having to research the fine print on the bottle.
 

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Discussion Starter · #10 · (Edited)
Well, I can tell you that the trans in a M2A2 Bradley uses 10w-30 for fluid, which also makes me think that a thin oil would be better than ATF. Of course it is also used in the engine and final drives, and is probably designed this way so Joe doesn't put the wrong oil in the wrong place. I'm not sure how straight 10 weight oil compares to ATF as far as viscosity is concerned, and as noted already, winter temps are a concern.


Mark
 

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IMHO, tcases aren't too fussy so long as the internal pump can push it around easy.

I think the biggest factor for atf being chosen is to eliminate the possibility of cross-contamination with an automatic trans - should input/ouput seals fail.
 

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I think the biggest factor for atf being chosen is to eliminate the possibility of cross-contamination with an automatic trans - should input/ouput seals fail.
That is a good thought. The trans & transfer assembly going down the assembly line in the trans plant, Both get the same fluid, that eliminates the possibility of the wrong fluid in the trans, and makes it easy to stock one fluid. Manuals trannys were made in NY, and shipped whole, so they were likely already topped off. Not sure how they did it in the 70's & 80's, but in 2000, they assembled the engine/trans/ & transfer into a unit, and shipped them to the assembly plant as one.
 

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most ATF's are 10w [ some foreign stuff is less - Honda ]
 
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