NP205 gear oil capacity/type? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Curbstone Mech · 01-22-2005, 11:35 AM

Just got our transfer case back from the shop,what to fill it before it goes back in.What is the capacity? Should it be 80-90 gear oil?
Thanks!

**kwmech** · 01-22-2005, 12:48 PM

Usually, little more than 1/2 gallon of 80-90

Curbstone Mech · 01-22-2005, 02:40 PM

Thanks Kw! Getting started on it right now.

Tully · 01-22-2005, 02:59 PM

I have dexron in my 205, is that bad? I was told you could use it. 80-90 is kinda thick at -30

badpeanut · 01-22-2005, 03:04 PM

I've heard automatic trucks should use tranny fluid, and manual trucks should use gear lube. It seems like a good idea if there is any leakage between the two. Any truth to this?

da-burb · 01-22-2005, 05:21 PM

Using tranny fluid in all of mine.

Vince M · 01-22-2005, 06:55 PM

Straight out of the factory service manual "SAE 80 GL-5 Gear Lubricant". It's what I ran in mine. I've seen and heard of auto tranny fluid in T-cases but sometimes it's in there because it has leaked through the adapter.

Vince M · 01-22-2005, 06:59 PM

I forgot to mention that the NP205 is gear driven but most of the other T-cases are chain driven and I'm pretty sure that the recommened lube for them is tranny fluid. Funny thing is I can't find a quantity for the NP205 in the manual.

4x4Poet · 01-23-2005, 01:23 AM

When I fill my NP205, I jack up the rear of the truck so I get in a little more. I use synthetic so I don't fear foaming.

HOTFUN · 01-26-2005, 10:53 PM

I am installing my rebuilt 350 engine and 350 tranny this weekend in the 72 GMC K20 so which is the correct fluid? I was planning on synthetic 75-90 for the 205? Does two quarts of this sound correct?

sbc350gearhead · 01-28-2005, 10:58 AM

Make sure whether your tranny calls for a GL-4 or GL-5 fluid, before you fill it.

**kwmech** · 01-28-2005, 11:22 AM

A couple of other chvey boards I frequent have had this discussion and debate quite a few times. The end result?--- The 205s are damn near indestructible. Pretty much if you have a decent quality oil in them, they will last, some oils however may let the the t-case generate more noise than others but will not 'hurt' them. If you worry about a seal breach between the trans and t-case then use matching oils. Personally I am getting ready to use another NV4500 in a truck I am building with a doubler. I'll be using the synthetic for the NV in both the 203 and 205. My understanding is if you get any other type of oil in the NV other than the required synthetic it will destroy it.

687980chevy · 01-29-2005, 02:54 AM

The NP205 holds 2.5 qts. prior to 1980 they had 85w90. In 80 GM switched to dextron I suspect for fuel economy. But in 80 they also redesigned the ouput shaft to a slip yoke instead of a slip shaft driveshaft I don't know if the redesign required the fluid change. In really cold weather when warming up the engine, put the transfer case in neutral and trans in high gear it will limber it up pretty quick.

Green 1959 · 09-07-2014, 01:39 AM

What if my truck is a 80 with a slip yoke? Also what is some ideas or recommandations for when the slip yoke leaks? Should a just replace the seal, replace the seal and yoke or I have heard of a conversion? There is a good amount of play back there and it is leaking kind nice.

01-22-2005, 11:35 AM	#1
Curbstone Mech Active Member Join Date: Feb 2000 Location: Carroll County Maryland Posts: 300	NP205 gear oil capacity/type? Just got our transfer case back from the shop,what to fill it before it goes back in.What is the capacity? Should it be 80-90 gear oil? Thanks! __________________ 68 short fleet 383 stroker, 700r4 373:1 posi 72 GMC 3/4 ton- weekly driver 700r4 351;1 posi

01-22-2005, 02:40 PM	#3
Curbstone Mech Active Member Join Date: Feb 2000 Location: Carroll County Maryland Posts: 300	Thanks Kw! Getting started on it right now. __________________ 68 short fleet 383 stroker, 700r4 373:1 posi 72 GMC 3/4 ton- weekly driver 700r4 351;1 posi Last edited by Curbstone Mech; 01-22-2005 at 02:41 PM. Reason: too short

01-22-2005, 05:21 PM	#6
da-burb "Ochre Ogre" Join Date: Apr 2000 Location: Springfield, MN Posts: 3,558	Using tranny fluid in all of mine. __________________ Bowtie Truck Stop Inc. Mid-West GM Truck Restoration Parts Supplier Your Key Parts, Auto Metal Direct, Dynacorn, and Goodmark dealer. like us @ www.facebook.com/BowtieTruckStop 1971 C-10 Suburban (Ochre) 1971 K-10 Suburban (Ochre) 1972 C-10 Suburban (Ochre) 1972 K-20 Suburban (Yellow- that just aint right!) Springfield, Minnesota 56087

01-22-2005, 06:55 PM	#7
Vince M Senior Member Join Date: Apr 2000 Location: Orlando, FL Posts: 1,076	Straight out of the factory service manual "SAE 80 GL-5 Gear Lubricant". It's what I ran in mine. I've seen and heard of auto tranny fluid in T-cases but sometimes it's in there because it has leaked through the adapter. __________________ ............................................................ 68 Chevy CST SWB w/LS1, carb & 700r4. Golden Anniversary clone with a few improvements.

01-22-2005, 06:59 PM	#8
Vince M Senior Member Join Date: Apr 2000 Location: Orlando, FL Posts: 1,076	I forgot to mention that the NP205 is gear driven but most of the other T-cases are chain driven and I'm pretty sure that the recommened lube for them is tranny fluid. Funny thing is I can't find a quantity for the NP205 in the manual. __________________ ............................................................ 68 Chevy CST SWB w/LS1, carb & 700r4. Golden Anniversary clone with a few improvements.

01-22-2005, 12:48 PM	#2
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,650	Usually, little more than 1/2 gallon of 80-90

01-22-2005, 02:59 PM	#4
Tully Registered User Join Date: Jan 2005 Location: Hiles, WI Posts: 42	I have dexron in my 205, is that bad? I was told you could use it. 80-90 is kinda thick at -30

01-22-2005, 03:04 PM	#5
badpeanut Not a bad nut after all.. Join Date: Dec 2000 Location: ND Posts: 1,759	I've heard automatic trucks should use tranny fluid, and manual trucks should use gear lube. It seems like a good idea if there is any leakage between the two. Any truth to this?

01-23-2005, 01:23 AM	#9
4x4Poet Registered User Join Date: Nov 2004 Location: "Under Montana skies." Posts: 1,836	When I fill my NP205, I jack up the rear of the truck so I get in a little more. I use synthetic so I don't fear foaming. __________________ '71 GMC K20 Suburban, '71 GMC K10 Suburban, '72 Chevy C10 CST Suburban, '72 Chevy K20 clunker pickup.

01-26-2005, 10:53 PM	#10
HOTFUN Registered User Join Date: Jan 2001 Location: Lincoln, Nebraska Posts: 2,145	I am installing my rebuilt 350 engine and 350 tranny this weekend in the 72 GMC K20 so which is the correct fluid? I was planning on synthetic 75-90 for the 205? Does two quarts of this sound correct? __________________ '66 CST BBW swb fleet 327 fac ac '67 CST 4x4 swb 327 stepside project '72 Cheyenne K20 50k original '72 Cheyenne Super K20 project '73 Sierra swb 4x4 frame off in paint stage '74 Cheyenne Super swb w/16k actual '71 & 72 Cheyenne K10 4x4 swb's '70 426 HEMICUDA conv SHAKER 4 sp Dana 60 '60 Impala conv 327 PG fac ac loaded 3rd owner '72 GMC K2500 4x4 '59 Apache CST BBW fleetside swb 283 '73 ElCamino SS LS1 T56 true SS bucket tach '76 ElCamino SS 52k survivor '87 Grand National 41k True 2nd to last built in 1987. '86 K30 454 SRW fleetside CA since new '88 Trans Am GTA 39k bought new 2018 DEMON plum crazy @ 840HP! "Need for speed" Last edited by HOTFUN; 01-26-2005 at 10:56 PM.

01-28-2005, 10:58 AM	#11
sbc350gearhead Registered User Join Date: Mar 2003 Location: Columbus Ohio Posts: 1,413	Make sure whether your tranny calls for a GL-4 or GL-5 fluid, before you fill it.

01-28-2005, 11:22 AM	#12
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,650	A couple of other chvey boards I frequent have had this discussion and debate quite a few times. The end result?--- The 205s are damn near indestructible. Pretty much if you have a decent quality oil in them, they will last, some oils however may let the the t-case generate more noise than others but will not 'hurt' them. If you worry about a seal breach between the trans and t-case then use matching oils. Personally I am getting ready to use another NV4500 in a truck I am building with a doubler. I'll be using the synthetic for the NV in both the 203 and 205. My understanding is if you get any other type of oil in the NV other than the required synthetic it will destroy it.

01-29-2005, 02:54 AM	#13
687980chevy Registered User Join Date: Feb 2004 Location: Hilly Southern Indiana! Posts: 201	The NP205 holds 2.5 qts. prior to 1980 they had 85w90. In 80 GM switched to dextron I suspect for fuel economy. But in 80 they also redesigned the ouput shaft to a slip yoke instead of a slip shaft driveshaft I don't know if the redesign required the fluid change. In really cold weather when warming up the engine, put the transfer case in neutral and trans in high gear it will limber it up pretty quick. __________________ 68 K-10,79 K-10,80 C-30 57 chevy convertible 79 Z28 Last edited by 687980chevy; 01-29-2005 at 02:57 AM.

09-07-2014, 01:39 AM	#14
Green 1959 Registered User Join Date: Mar 2011 Location: Arizona City Posts: 353	Re: NP205 gear oil capacity/type? What if my truck is a 80 with a slip yoke? Also what is some ideas or recommandations for when the slip yoke leaks? Should a just replace the seal, replace the seal and yoke or I have heard of a conversion? There is a good amount of play back there and it is leaking kind nice. __________________ I pity the fool with only 2 headlights!

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