Transfer case fluid change interval

jfkmk

Original poster
Member
Mar 7, 2013
91
I've heard a lot about making sure the transfer case fluid is replaced at the 50K mark. I changed the fluid at about 45K because I started to tow with the vehicle and wanted to make sure all fluids remain in top condition, so I guess I'm safe. I was curious, though....what happens if you don't change the fluid? How and why would the transfer case fail if the fluid isn't changed at 50K?

Thanks!
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
IIRC, even if you don't use the 4x4 the clutches in the t-case are still turning and the fluid gets dirty and wears out. That causes the clutches to wear prematurely. Roadie can expand on this.
 

kkoether

Member
Aug 18, 2013
37
Wooluf1952 said:
IIRC, even if you don't use the 4x4 the clutches in the t-case are still turning and the fluid gets dirty and wears out. That causes the clutches to wear prematurely. Roadie can expand on this.

Before I realized how short the life of this fluid was ours started shuddering at low speeds sort of like the transmission slipping. When I drained the fluid it looked like old dishwater. We had only put about 20000 miles on it since we bought it. It's not that hard to change and not that expensive. It's now on a 35000 mile rotation with me. New fluid and all the shuddering disappeared.
 

CaptainXL

Member
Dec 4, 2011
2,445
jfkmk said:
How and why would the transfer case fail if the fluid isn't changed at 50K?

A fundamental principal of motor oil, trans, diff and t-case oils is that they provide 5 properties.

1. Lubrication
2. Cooling
3. Suspension
4. Hydraulic
5. Cleaning

If fluids are not changed on a timely basis either when a scheduled inspection or an oil analysis indicated then you will see the following.

1. Increased wear of metal components (clutches, bearings, etc)
2. Lack of cooling
3. Inability to suspend contaminants
4. Reduced ability to clean
 

hockeyman

Member
Aug 26, 2012
726
Since July of 2012 (when I bought my Envoy at 118k), I've changed every fluid in it. And by far, the two worst looking fluids that were flushed were the trans and rear diff fluids.

I put about 6k non-harsh miles on my Envoy per year, so I figured I'd re-change all of the fluids again once every two or three years. A little bit of preventive maintenance goes a long way :thumbsup:
 

jfkmk

Original poster
Member
Mar 7, 2013
91
hockeyman said:
Since July of 2012 (when I bought my Envoy at 118k), I've changed every fluid in it. And by far, the two worst looking fluids that were flushed were the trans and rear diff fluids.

I put about 6k non-harsh miles on my Envoy per year, so I figured I'd re-change all of the fluids again once every two or three years. A little bit of preventive maintenance goes a long way :thumbsup:

I'm with you, and believe me, all my vehicles have always been pampered. I know the fluids are the life blood of my vehicle and make sure they stay fresh. It's just that this is the first vehicle I've heard of that needs the transfer case changed at 50K. I had a Blazer before this, and never changed the transfer case fluid, and in 150K never had a problem. My friend's Explorer has 200K+ and has never changed it. I've just never heard so many dire warnings about changing this particular fluid and was wondering what makes this transfer case so different.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
For some odd reason (GM cheap-ass designers), the seals may also be a dime cheaper than units in the past, and part of the fluid change interval being so low is to force people to go check the level.

They also assume folks are going to overuse the A4WD mode, and that mode is a LOT harsher on clutches than 2HI or 4HI, because of the slippage.

In any event, many owners never check the level or change it, being typical American owners who give the Owner's Manual zero respect. And thousands of them don't have premature failures. But as an enthusiast forum, we feel the need to spread the word about the incidents we HAVE heard about since the platform came out, and a number of them at low mileage between 50 and 100K are scary.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
kkoether said:
Before I realized how short the life of this fluid was ours started shuddering at low speeds sort of like the transmission slipping. When I drained the fluid it looked like old dishwater. We had only put about 20000 miles on it since we bought it. It's not that hard to change and not that expensive. It's now on a 35000 mile rotation with me. New fluid and all the shuddering disappeared.

I had almost the same problem, but it only happened when it was in A4WD. Changed the fluid at about 30k miles and all has been good since. Of course I almost never use A4WD any more.
 

kkoether

Member
Aug 18, 2013
37
Wooluf1952 said:
I had almost the same problem, but it only happened when it was in A4WD. Changed the fluid at about 30k miles and all has been good since. Of course I almost never use A4WD any more.

We don't have that option with the Rainier. It is Full Time AWD. That probably explains the quick wear on the fluid.
 

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