t case oil?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mothertrucker424 · 02-14-2008, 12:45 PM

this may sound stupid but i have heard a 205 take either ATF or gear lube

which is correct and what weight oil/atf should i use?

Dads 68 GMC · 02-14-2008, 12:49 PM

you can use either one, I use 80/90 gear lube,I think it would be a little quieter than atf. synthetic would probably be great.

hdflstf · 02-14-2008, 02:50 PM

From what I have seen, GM recommends gear oil for earlier years and then changes to ATF in later years for the same transfer case. Gear oil in mine.

**Stocker** · 02-14-2008, 10:59 PM

I've also heard either is OK, but I run gear oil... However, when the seal between the trans and t-case was leaking, ATF would be pumped into the t-case. When the trans needed topping off, it was time to drain the excess from the t-case. Having both oils in there never hurt it at all...

1969k10stepside · 02-14-2008, 11:42 PM

I use gear oil in my np205.The only way mine will have atf in it is if the seal was letting it leak in..

Wreckless_71 · 02-14-2008, 11:50 PM

I guess I'm the only guy running ATF then, eh... Well the General recommends that you use ATF in the transfercases on all newer models, I consulted my dad who has been a mechanic for almost 30 years and he said to run the ATF, on the other hand I do have a 250 gallon tank of gear oil in the shop so I could've done either or.

cobinder · 02-15-2008, 12:05 AM

I run what ever is in the tranny. Auto tranny run ATF, NV4500 run syn, Manny tranny run gear oil. The 205 is a tough TC, she don't really care as long as it's plentiful and clean.

mudmilitia · 02-15-2008, 08:39 AM

Gear oil here!

Duro5341 · 03-05-2008, 02:31 AM

synthetic ATF in my NP208......230,000kms all original....going strong.

GM recommends dex III ATF in the NP208, so run it.....

Duro

**MJN** · 03-08-2008, 07:01 PM

NP205's run 80w90 since it's an all gear t-case. You can use 85w140 also.

Burt4x4 · 03-08-2008, 07:45 PM

yup, I am with the 80-90 gear oil crowd. I have the SM465/NP205 combo both filled with 80-90w

**jaros44sr** · 03-08-2008, 11:11 PM

Mine was running ATF, not by choice, seals let go

Since my 205 has gears in it, I plan to run gear oil, heavier the better, JMHO

Hoods69BadBowTie · 03-09-2008, 02:50 AM

Yea I agree 205 should be 80/90 gear oil. I got ATF fluid in my 208.

muscletrucks · 03-09-2008, 04:01 AM

Gear oil, recommended by dealer parts department.

Dooley · 03-30-2008, 10:38 AM

Quote:

Originally Posted by mothertrucker424

this may sound stupid but i have heard a 205 take either ATF or gear lube

which is correct and what weight oil/atf should i use?

When I had my 1972 it called for 80/90 gear lube in the 205.
When I had my 1980 it called for 30w motor oil in the 205.
My 1988 V 30 calls for ATF in the 205.
They all work.

69CST4x4SWB · 01-17-2012, 05:34 AM

Quote:

Originally Posted by Dooley

When I had my 1972 it called for 80/90 gear lube in the 205.
When I had my 1980 it called for 30w motor oil in the 205.
My 1988 V 30 calls for ATF in the 205.
They all work.

I think it is due to tighter clearances in newer TC's and tranny's, that is why thinner fluids are used in them. If you tried putting 80/90 in your 1988 you would have a hard time shifting it.

coops714x4 · 01-17-2012, 12:49 PM

My 205 has ATF, when I redo my truck I am going to change tranny, currently it has a SM465 and I am going to swap in a NV4500 then I will run synthetic. alot of older truck from the north will have ATF in them, that way they could shift the TC easier when cold.

Dooley · 01-22-2012, 03:00 AM

Quote:

Originally Posted by mothertrucker424

this may sound stupid but i have heard a 205 take either ATF or gear lube

which is correct and what weight oil/atf should i use?

My 1972 called for 80/90 gear oil in the case
My 1980 called for 30w motor oil in the case
My 1988 calls for ATF in the case.
They all work in a 205.

*72lb4x4* · 01-22-2012, 03:10 AM

Interesting resurrection...

Did these 72, 80, and 88 supposed callouts specify the TC? 72 is 205; 80 may be 203 or 205; 88 may be 205 or 208.

I think a 208 uses ATF and I don't know what a 203 wants.

So it seems to be more complicated than ATF is good for all...

67swb72klb · 01-22-2012, 03:18 AM

mine was filled with atf by the p/o i took the check plug out and it was 3qt over filled drained all of it and replaced with 80-90

Dooley · 01-22-2012, 03:22 AM

Quote:

Originally Posted by 72lb4x4

Interesting resurrection...

Did these 72, 80, and 88 supposed callouts specify the TC? 72 is 205; 80 may be 203 or 205; 88 may be 205 or 208.

I think a 208 uses ATF and I don't know what a 203 wants.

So it seems to be more complicated than ATF is good for all...

The info I posted is correct for a 205 transfercase.
There were no GM 203's in 1980.
My 1988 V30 has the factory 205. I bought these trucks new.

Pics are from my 1980 K and my 1988 V30 truck owner manuals. Nothing supposed here.

**Stocker** · 01-22-2012, 10:33 AM

Quote:

Originally Posted by 67swb72klb

mine was filled with atf by the p/o i took the check plug out and it was 3qt over filled drained all of it and replaced with 80-90

That sure sounds like bad seals between the trans and the t-case... has it been OK since you put gear oil in?

67swb72klb · 01-22-2012, 12:51 PM

Quote:

Originally Posted by Stocker

That sure sounds like bad seals between the trans and the t-case... has it been OK since you put gear oil in?

yes none so far they must have filled it up on a bench i dont know how they got that much in it

02-14-2008, 12:45 PM	#1
mothertrucker424 Registered User Join Date: Sep 2006 Location: st pete Posts: 404	t case oil?? this may sound stupid but i have heard a 205 take either ATF or gear lube which is correct and what weight oil/atf should i use? __________________ _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_- 1972 K10 4"lift 33"tires (soon to be bigger and better) 2000 silverado 1500 2wd 2"coil spacers3" BL 285/75/16's

02-14-2008, 12:49 PM	#2
Dads 68 GMC Registered User Join Date: Feb 2006 Location: Sidney; MT Posts: 172	Re: t case oil?? you can use either one, I use 80/90 gear lube,I think it would be a little quieter than atf. synthetic would probably be great.

02-14-2008, 02:50 PM	#3
hdflstf Registered User Join Date: Oct 2007 Location: Desert Southwest Posts: 540	Re: t case oil?? From what I have seen, GM recommends gear oil for earlier years and then changes to ATF in later years for the same transfer case. Gear oil in mine.

02-14-2008, 10:59 PM	#4
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,727	Re: t case oil?? I've also heard either is OK, but I run gear oil... However, when the seal between the trans and t-case was leaking, ATF would be pumped into the t-case. When the trans needed topping off, it was time to drain the excess from the t-case. Having both oils in there never hurt it at all... __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

02-14-2008, 11:42 PM	#5
1969k10stepside Registered User Join Date: Mar 2006 Location: USA Posts: 21,019	Re: t case oil?? I use gear oil in my np205.The only way mine will have atf in it is if the seal was letting it leak in.. Last edited by 1969k10stepside; 02-14-2008 at 11:47 PM.

02-14-2008, 11:50 PM	#6
Wreckless_71 Registered User Join Date: Apr 2007 Location: Kelso, WA Posts: 363	Re: t case oil?? I guess I'm the only guy running ATF then, eh... Well the General recommends that you use ATF in the transfercases on all newer models, I consulted my dad who has been a mechanic for almost 30 years and he said to run the ATF, on the other hand I do have a 250 gallon tank of gear oil in the shop so I could've done either or. __________________ 1972 K10 4" lift, 35’s, 383 stroker, 700r4, current project. 1971 C10 3"/5" static drop, 355/350. "La Bamba.” The current daily driver.

02-15-2008, 12:05 AM	#7
cobinder Everything is work in progress Join Date: Apr 2006 Location: Denver Colorado Posts: 326	Re: t case oil?? I run what ever is in the tranny. Auto tranny run ATF, NV4500 run syn, Manny tranny run gear oil. The 205 is a tough TC, she don't really care as long as it's plentiful and clean. __________________ Good luck with your truck! How much?! It's just an old truck part!! 49 International on a 80 GMC 3/4ton 4x4 chassis 48 International KB-5 2 ton dump bed 04 Honda CRF "500" 09 Honda CRF450 fuel injected rocket 03 Suzuki hayabusa carbonfiber wheeled monster. 02 Ford diesel stretch van (toy hauler) 01 38' Monaco diesel pusher motorhome

02-15-2008, 08:39 AM	#8
mudmilitia Registered User Join Date: Jan 2007 Location: ontario ny Posts: 31	Re: t case oil?? Gear oil here!

03-05-2008, 02:31 AM	#9
Duro5341 Registered User Join Date: Dec 2006 Location: Earth Posts: 239	Re: t case oil?? synthetic ATF in my NP208......230,000kms all original....going strong. GM recommends dex III ATF in the NP208, so run it..... Duro __________________ -1986 K10 LWB, 350 HD,TH400 3.08, 30 spline 10 bolt, with an Auburn Posi, 31" tires All original, second owner truck -1979 Monte Carlo, 350, 200r4, 3.73 posi -1987 GT T-top Mustang - slow moving project

03-08-2008, 07:01 PM	#10
MJN Registered User Join Date: Feb 2000 Location: Maquoketa, Ia/ Orr, Mn Posts: 3,052	Re: t case oil?? NP205's run 80w90 since it's an all gear t-case. You can use 85w140 also. __________________ '51 South Bend Model "9A" '56 Chevy 3600 NAPCO '74 Chevy Cheyenne Super K20-restored on 37's '72 GMC Sierra Custom K2500- in progress '08 GMC Envoy Denali '12 GMC Sierra 2500HD Denali '17 GMC Yukon XL VCCA member #58596 http://www.nohrco.com

03-08-2008, 07:45 PM	#11
Burt4x4 Registered User Join Date: Feb 2000 Location: Modesto, CA Posts: 1,842	Re: t case oil?? yup, I am with the 80-90 gear oil crowd. I have the SM465/NP205 combo both filled with 80-90w __________________ 1972 K5 MPFI454/Sm465/Np205/D60/14FFd/Re-Centerd H1s w/Swamper Iroks

03-08-2008, 11:11 PM	#12
jaros44sr Senior Member Join Date: May 2006 Location: Philadelphia, Pa. 19454 Posts: 9,766	Re: t case oil?? Mine was running ATF, not by choice, seals let go Since my 205 has gears in it, I plan to run gear oil, heavier the better, JMHO __________________ Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim

03-09-2008, 02:50 AM	#13
Hoods69BadBowTie Chevys Kick A$$ Join Date: Jan 2005 Location: Zootown, MT Posts: 12,699	Re: t case oil?? Yea I agree 205 should be 80/90 gear oil. I got ATF fluid in my 208. __________________ HOODS is what I answer too -'79, '77, '88 Pickup Sold, '85 Camaro, '83 T/A, '81,'83,'90 K5 Blazer All Sold -'79 3/4 ton "Big Yellow Bananna" Lifted 4spd. 39.5 TSL Swampers, The money Pit -'86 K5 Blazer Silverado 6.2 4" lift 35"s -'95 Ext. Cab Shorty 4" Tuff Country rolling 35" M/T's -'83 Monte Carlo T-Tops. 126,500 Original Miles -LATER I would rather push a Chevy then drive a ford!!

03-09-2008, 04:01 AM	#14
muscletrucks Registered User Join Date: Mar 2008 Location: Kansas City Posts: 431	Re: t case oil?? Gear oil, recommended by dealer parts department.

01-17-2012, 12:49 PM	#17
coops714x4 Registered User Join Date: Mar 2011 Location: Cement Oklahoma Posts: 916	Re: t case oil?? My 205 has ATF, when I redo my truck I am going to change tranny, currently it has a SM465 and I am going to swap in a NV4500 then I will run synthetic. alot of older truck from the north will have ATF in them, that way they could shift the TC easier when cold. __________________ 1971 K20, Coop's beast (project) 1972 C30 wrecker, "Big Ernest" (SOLD) 1975 K5 Blazer (wife's toy) she got it in the divorce 2014 Street Glide Special 1983 K20 Big Block, auto (work horse)



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01-22-2012, 03:10 AM	#19
72lb4x4 Account Suspended Join Date: Jul 2006 Location: DFW Posts: 1,427	Re: t case oil?? Interesting resurrection... Did these 72, 80, and 88 supposed callouts specify the TC? 72 is 205; 80 may be 203 or 205; 88 may be 205 or 208. I think a 208 uses ATF and I don't know what a 203 wants. So it seems to be more complicated than ATF is good for all...

01-22-2012, 03:18 AM	#20
67swb72klb Registered User Join Date: Dec 2010 Location: livingston co.mi Posts: 2,471	Re: t case oil?? mine was filled with atf by the p/o i took the check plug out and it was 3qt over filled drained all of it and replaced with 80-90 __________________ California 65 GTO---Texas 64 burb 283 ---Oklahoma 67 CST SWB BBW wood bed 327 2004r---New Mexico 72 k10 350 350 auto---Georga 72 short step project

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