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NP205 oil dispute

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by DieselDan, Jan 7, 2002.

  1. DieselDan

    DieselDan 1/2 ton status

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    OK it seems the NP205 transfer case originally came (from the the factory) filled with 80/90 gear oil, but at some point the factory changed to ATF(!?) for better fuel economy, right? Does any one know when this change took place? Did New Process actually make any internal changes to the 205 to run such a thin oil? What the hell do you guys use?

    This got me all fired up when we replaced a front output seal on one and ATF dribbled out. Holy crap, I say, should be gear oil in here! Then a coworker says nope, look at the manual "ATF". I KNOW my ancient Dodge manual quotes 80/90W for the NP205.


    Real trucks don't have spark plugs!<P ID="edit"><FONT class="small">Edited by DieselDan on 01/07/02 10:29 AM.</FONT></P>
     
  2. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Here is what I have gathered over the years. Most of the older 205's came factory with gear oil, but some newer ones MAY have come with ATF for better fuel mileage. The local tranny/t-case guru says that ATF can be used especially in colder climates (colder than most of us see, unless you live in Canada or Alaska). He recommends (at least here in the NorthEast) that I run gear oil. It provides better lubrication at higher highway temps, and it never gets too cold for gear oil. The parasitic loss associated with the gear oil as compared with ATF is negligable, so for the added protection he feels gear oil is better suited for our climate. He says you "probably" won't hurt a 205 with ATF and you can run it (especially in extremely cold climates), but the gear oil provides better wear protection under high heat and heavy use conditions, so that's what HE suggests. Again this is not gospel and isn't backed by scientific proof, but it does make sense. My 1980 205 had ATF in it when I bought it in 92 (not sure if it was original or not), but it had low mileage and the shift forks were worn, so when I bought the rebuild kit (93) from him, he told me to fill it up with gear oil instead of ATF. FWIW.

    See my rig at <a target="_blank" href=http://coloradok5.com/gallery/Leadfoot> click here </a>
     
  3. four_by_ken

    four_by_ken 1/2 ton status

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    Of all the people I know, non run ATF in their 205. All use gear lube.

    Ken H.


    '86 K5 in parts
    1-ton 454 44 TSLs
     
  4. marv_springer

    marv_springer 1/2 ton status

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    I've experimented with ATF.... I started running it in the 203 of my Doubler after I realized the 90W filled Doubler zapped me for nearly 2 mpg..!!

    I've been running it in there for almost 2 years w/ no problems.

    Marv
     
  5. m j

    m j 1/2 ton status

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    I thought eastern state got nasty cold
    Cheech and Chong movie seemed to show cold

    formerly 77chev
     
  6. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Don't get me wrong, it does get cold (and sometimes very cold) around here, but not for any extended length of time (just "cold spells"). The people who have to worry are the ones that don't get above freezing day after day, night after night, week after week. For us (Mass) that rarely happens for more than a day or two at a time and then it warms up for a little bit (cycles). A common expression in New England is "If you don't like the weather, wait five minutes, and it will change".....and conversly, "If you like the weather, just wait five minutes, and it will change". It's an exaggeration, but you get the point. It rarely stays too hot or too cold for any length of time, the only thing we usually worry about is precipitation amounts (usually floods/blizzards or droughts). Oh well that weather in New England [​IMG][​IMG]

    See my rig at <a target="_blank" href=http://coloradok5.com/gallery/Leadfoot> click here </a>
     
  7. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Why not try a synthetic gear oil. It will be more stable across a wider range of temps.
    I went to a sythetic oil on my manual tranny in my supra to help with hanging synco's. Made a world of difference.
    The trend has been to go to thinner lubricants to lower paresetic loss to improve millage. Most GM motors want you to run a 5w30 on the newer ones for the same reason. I'm starting to go to synthetic so I can get the better lubrication at higher temps but have the more stable viscocity. Right now I'm running sythetic in my manual tranny and engine on the Supra and going to be putting sythetic in the crate in the Lady's K5 next go around. She's bad about not letting it warm up when it cold. Figure that since it's new and I know it has good seals this may be the best solution.

    Women dig dents and flat paint!
    coloradok5.com/gallery/Grim
    75 Jimmy, Dollar
    Grim-Reaper
     
  8. Boss

    Boss 1/2 ton status Author

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    In my old K5 with a 205, I ran it with 90w gear oil. I had an auto tranny and "heard" some people saying, manual tranny, run gear oil in Tcase, with auto, run ATF in Tcase. So, I gave it a try and the damn tcase started leaking. So, switched back to Gear oil and went on about my business.
    Boss

    Pic of my truck Before N' After
    <a target="_blank" href=http://coloradok5.com/gallery/BeforeNAfter>http://coloradok5.com/gallery/BeforeNAfter</a>
     
  9. DieselDan

    DieselDan 1/2 ton status

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    Yes, I know (now,) New Process did this, BUT does anyone know when they decided to change to ATF? And did New Process make any internal changes after the switch?

    PS. This isn't my truck. I would definately use gear oil (maybe synthetic).

    Real trucks don't have spark plugs!
     
  10. prjt_blzr

    prjt_blzr 1/2 ton status

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    The local driveline place here in Colorado Springs says that all the parts are the same. There have been no changes to accomadate ATF or motor oil or gear lube. You order the same part numbers for the Tcase. I've not verified this anywhere else but it seems to make sense.

    I run syn. gear oil in my 205 that matches the gear lube in the NV4500. That way if there are any leaks between the two it is no big deal.
     
  11. RGF

    RGF 1/2 ton status

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    I just drained a TH400 version 205 from an 86 a week ago for shipping and it had ATF in it,it also had the fiqure 8 style adapter with the long 32spline input gear. The transmission shaft stick-out was the same as the shaft stick-out for using a NP208 transfer!
    I have messed with some 205 transfers over the years and noticed that in 81 or 82 NP went to a different type of sliding clutch assembly for locking it into 4WD,it has a completely different design with some parts made from alum.
    I think this design makes it easiler to get it in and out of 4wd and if I was to take a guess this would be about the time they decided to use ATF instead of gear oil.
    I dont think it would hurt to use either type of oil depending on your climate but the case will have more leaks with the ATF since most of the holes on a 205 are thru holes and the bolt threads will require some type of sealer on them.

    RGF
     
  12. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I have an 85 TH400 205 that is spec'd for ATF but is now running GL5 (80/90). I've been told that there are no differences in parts or tolerances and that it is ok to run either.

    I've heard this from various sources but I have no hard evidence or documentation one way or the other. So, I decided to do some research. New Process is a division of New Venture now so, I started with <a target="_blank" href=http://www.newventuregear.com/index.html>http://www.newventuregear.com/index.html</a>. They wouldn't let me talk to (or didn't have) any "tech support" people but they gave me the number of a company that sells, modifies, remans, and generally knows their way around these NV/NP transfer cases, especially the 205. I spoke with one of their tech guys briefly. Basically, he confirmed what I said above. Tolerances and parts were not changed for ATF units. He said they use and recommend GL5 in all 205s or 20/50 synthetic for reduced parasitic effect or extreme cold.

    BTW, this company just bought a large stock (the last of NV's NOS if I understood correctly) of brand new NP205s with 32 spline female inputs. I didn't think to ask about the fixed/slip yoke. [​IMG] Anyway, they want $1595.00 for them if anyone is interested.

    Russ

    85 K30 CUCV, 350 TBI, TH400, 205, D60/C14, 4.56 Locked
    Some day: 4" lift, 44" tires, massive cutting, shorter wb and rear overhang.
     
  13. DieselDan

    DieselDan 1/2 ton status

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    Thanks ALL. Great info! This board never ceases to impress me.


    Real trucks don't have spark plugs!
     
  14. K5 NUTT

    K5 NUTT 1/2 ton status

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    Don't quote me as its late and i don't feel like runnin down the stairs into the garage to open the appropriate Helms manual...gottem all..hehehe. It appears if memory serves me correctly...either in 1987...or most definately when the C/K designation was dropped ant the 1 tons that became the R/V series which still came with the NP205 started running ATF....and Marv....if you gained 2MPG....i'm in like flin bro!!!

    Azblazer

    1979 K5 350 TBI
    1976 K5 Chalet
    If it ain't got arizona pinstriping.....you ain't wheelin the pee outa her!
     
  15. Wheels

    Wheels 1/2 ton status

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    NP 205 use gear oil and NP 203 use 10w/40 motor oil. The use of ATF in the gear boxes was an alternative to help the internal parts move during extreme cold weather. This was prior to the introduction and acceptance of synthetic oil. AMS Oil has two different grades of gear oil (regular and racing). Racing is thinner and is green in color. Grim-Reaper is right in that synthetic remains stable through a broader temp range than fossil derived products. ATF will work but it has different lubrication properties and will accelerate wear in the t-case. My vote would be synthetic and use ATF in automatic transmission where it was designed to be used.
     
  16. chevyguybc

    chevyguybc 1/2 ton status

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    great post, i will bring it back,! haha, its from 2002 but it just saved me from putting atf in my np205 , goign with synthetic, thanks all
     
  17. 79k20350

    79k20350 3/4 ton status

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    what do you mean saved you? There is absolutley NO HARM in running atf in a 205

     
  18. roadnotca

    roadnotca 3/4 ton status

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    Hmmmm. I have a 208 that weeps ATF. Its worth a try; Mobil1 75W-90 Synth, comin up!
     
  19. 79k20350

    79k20350 3/4 ton status

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    NO, NO, NO!!!!!! 208's CAN ONLY USE ATF!!!!!!! You'll f' the thing uo something fierce if you do that:eek1:
     
  20. imiceman44

    imiceman44 1 ton status

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    Not true
    It's gears and a chain, low viscosity gear oil like synthetics should be fine, there is no nead for ATF other than it's thin condition, plus the fact that if a seal blows in the tranny the same kind of fluid will flow into the Tcase.
     

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