Transfer Case oil- straight mineral oil vs. gear oil

Discussion in 'General IH Tech' started by Chad Bailey, Aug 30, 2020.


  1. Chad Bailey

    Chad Bailey Farmall Cub

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    Hi all-
    The correct spec for my Dana 18 transfer case oil is Straight Mineral Oil SAE 80W-90, but the closest thing I find at most auto parts stores is a Lucas SAE 80W-90 gear oil for trans & diff. Any reason I should NOT use the Lucas gear oil?
     
  2. steve bridge

    steve bridge Farmall Cub

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    I get my 90 mineral oil at the local IH dealership. I take my own jug as they have it in bulk. I've always used it, but have found gear lube in units I bought. Some boxes (don't know about IH) have brass alloys that don't like gear lube, so I always figured I would use what IH said to use.
     
  3. mallen

    mallen Y-Block King

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    80W90 "Mineral oil" IS gear oil. It's also called 80W90 GL-1 gear oil. GL5 gear oil is what you use in your differential. GL5 and maybe GL4 (not sure about 4) MAY have addatives that can damage your transmission. Or it may not. Some GL5 specifically says it's ok. But I honestly don't trust that because there are a lot of companies, even reputable brands, that sell crap that will screw up your old vehicle. They can get away with it, because no marketing can put all.oat anything on the bottle, but you can't really prove that their product destroyed your 50 year old engine or transmission. So let the buyer beware. (If it was supposed to be gl1 oil and they put GL5 in the bottle, that's not only easy to prove, you'd smell it, because GL5 stinks) since I have nothing that uses GL4, I'm only passingly familiar so hopefully someone else will home in on that.

    GL1 can be hard to find. My transfer case takes 90w gl1 "mineral oil". I use "Ford tractor transmission fluid" from tractor supply co. The bottle is marked "90w gl1". Napa can usually order most anything you need. You might be able to get 80w90 there.
     
    Last edited: Aug 30, 2020
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  4. gillis51

    gillis51 Binder Driver

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    Napa has there own GL1. I believe a 1 gal jug is around $20.00. Been using it for years. Other option is Valvoline VR1 50 weight but it’s around $6 a quart around here.
     
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  5. 1975IH200

    1975IH200 Y-Block King

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    SAE90 GL-1 Mineral Oil.jpg
    Available at Tractor Supply Co.
     
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  6. mallen

    mallen Y-Block King

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    While people use 50 weight detergent motor oil, I was always taught that detergent oils like Valvoline 50w racing oil go in things that have oil filters like a typical engine while non detergent oils like 80w90 GL5 gear oil or 90w gl1 "mineral" oil go in things that don't have oil filters like differentials for GL5 gear oils or an NP205 transfer case for GL1 90w
     
  7. Dana Strong

    Dana Strong Lives in an IH Dealership

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    The Detergent vs Non-Detergent wrt filters vs no-filter does apply to engines where the products of combustion are of concern, but in a clean, not grossly overworked gearbox, I am not aware that detergents have an detrimental effect. I just yesterday topped-off the oil of an X-ray machine gearbox with some (Shell?) Aircraft 50wt oil. Maybe, FWIW, tomorrow I can check all the specs on that bottle and post a picture of them here.
     
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  8. Ron A

    Ron A High Wheeler

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    I ran Aeroshell 50wt for a long time. Never had a problem with it in a Dana 20.
     
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  9. Ron A

    Ron A High Wheeler

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    Mallen, I think that goes back to the days when internal combustion engines had no filtering systems, or at best bypass systems. I remember old timers running non detergent 30wt, in those. Then they would add an engine flush right before draining the crankcase.
     
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  10. mallen

    mallen Y-Block King

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    That's consistent with what I was told. The idea is that contaminants settle out. An engine flush presumably was detergent addatives to suspend those, then dump it all and repeat.
     
  11. Chad Bailey

    Chad Bailey Farmall Cub

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    Thanks! This is very helpful. My local Tractor Supply probably carries the 90W GL1 so I'll take a look there and use Napa as a backup option. Very much appreciate your input.
     
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  12. Chad Bailey

    Chad Bailey Farmall Cub

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    Thanks for posting this! I have a Tractor Supply nearby so will check that out.
     
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  13. Chad Bailey

    Chad Bailey Farmall Cub

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    Hi Mallen- I have a follow up question for you. Hope you don't mind. After removing the fill plug on the transfer case, a lot of oil came out... far more than I would expect considering it should only be full to the bottom of the fill port. Any idea how it's possible that the oil level was higher than the port?
     
  14. mallen

    mallen Y-Block King

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    On my new process transfer cas there are two plugs,one high one low. I assume yours is the same and you removed the upper one. I can think of a few ways it could be overfilled. It could have been jacked up so the vehicle was sitting at a steep angle when it was filled. Or someone could have pumped a bunch in with a transfer pump and a tightly fitting hose and then pulled out out and got the plug in fast before it drained out. Are you certain you have the right plug? If it were a transmission and not a transfer case I'd think maybe someone took the shifter off and filled it that way. I'm not specifically familiar with your model. My xfer case is divorced, but yours is married to the transmission right? Does it share lubricant with the transmission? Or do they drain separately? I think someone else will need to chime in here. But I recall something about some xfer case that could be filled through a breather at the top and also about a married transfer case where the transmission oil would drain thought the bearing into the transfer case. Don't know if it was your type or not.
     
    Last edited: Sep 1, 2020
  15. Ron A

    Ron A High Wheeler

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    If you are overfilled in the transfer case the first thing I would do it check the transmission level. You could have a bad seal leaking transmission fluid into the transfer case.
     
  16. Dana Strong

    Dana Strong Lives in an IH Dealership

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    Do you have a D-18 in a Scout II (per your picture)? Which transmission? I don't remember the D-18 well, but with a D-20 behind a T-18, the seal is in the adapter plate between the two boxes. Ron's explanation sounds most likely to me.
     
  17. Chad Bailey

    Chad Bailey Farmall Cub

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    Thanks for the quick replies, all. My transmission is a T-19 four speed manual, with a Dana 20 transfer case(I incorrectly took it for an 18 but with more reading realized the C18 marking on the case doesn't necessarily mean it's an 18).

    Also, here's a photo of the transfer case with the fill plug removed.
    IMG_3723.jpg
     
  18. Greg R

    Greg R Lives in an IH Dealership

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    I stopped using Lucas products about 8 years ago. I won't touch their products. Aside from Forrest's hard work and building a growing company; I don't cotton to his and other's lobbying efforts to privatize public lands and fronts such as "Protect the Harvest". For us that means less national parks, and less open areas available for off road and other adventures while vast stretches come under corporate control with reduced oversight on environment and water rights.
     

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