Transfer case fluid and rear axle fluid- do I need to change?

Hello all,

I have been looking over my owners manual and it states that I should have the transfer case fluid and rear axle fluid checked/ changed in my 2004 Silverado. I have 70,000 miles on the truck. Are they due for a change? Thanks.

It depends o when you usually get rid of the truck. If you want to go to 160,000 miles, you would probably change fluid now. I think your truck came with an owner’s manual, unlike many vehicles these days.

Yes, just make sure the right fluid is used.

Yes. If you tow anything with the truck - double yes.

do I need to brush & floss ?..

only the ones you’d like to keep.

If you have seldom used 4wd, maybe the transfer case could be a lifetime lube. But at 70k, I would give the rear differential attention. Many Silverados had limited slip. If it does, it is WAY overdo. Changing fluids in these areas is often a function of use. If you have done some off roading in wet conditions, I would change them for sure. Stream fording leaves little doubt that such fluids can be vulnerable. It’s pretty cheap insurance…

They may take different lubricants…GL-5 gear oil in the axles and ATF or even motor oil in the transfer case. Check before you change…

Thanks for the advice. Truck only uses 4wd in the winter months a few days a year. However, I believe in preventitive maint. and I think my truck needs some attention right now before something does happen. I will start by opening up the owners manual. Thanks again!

I have been driving more than 60 years and have never changed the oil in the differential, nor had any trouble with one. However I only had 140 K on the last one. Maybe in another 100k, i might have had trouble.

sjd181…I would encourage you not to be a seldom 4wd user. Make it a habit and look for reasons to use 4wd as frequently as safely can be done for lubrication and seizing purposes, usually once a month for a few miles. My owners manuals as i recall, recomended it. That is one of my reasons I would hesitate to buy a 4wd from an owner who bragged they never, seldom put a part time system into 4wd. They are robust, meant to be used, and in my experience, where as many problems stem from lack of use as too much.

Especially true of 4wd actuators and switches in electric systems. Remember that using 4 wd spreads the drive train load out over all the wheels and can add to the life of the entire drive train in situations that demand it. Towing up steep slopes, any excessive spinning in 2wd etc. you should take advantage of 4wd, especially given the inherrant weight imbalance of them to begin with. Many 4 wd owners don’t get it and drive them around like a 2 wd truck, even in mild times of need.

I also agree with Elly that with average use, standard open differentials can last a very long time with topping off maintenance only. But, if you have done a lot of “spinning” on ice over the years, towing or have a locking or mechanical limited slip which many GM truck 4wds come standard with, you are begging for a big ticket repair job if you don’t stay on top of them. “On top of” means checking/changing as per owner’s manual.

I change my transfer case fluid at about 30 -40 thou. Axels checked at that time. Changed at 60-80 thou. I now have 328,xxx and counting. No problems with the transfer case or axels. You should use the 4x4 system at lease once a month. All the gears get lubed as you drive. The problem is all the actuators will seize from lack of use. If you have limited slip it takes a additive. Also FYI I just went thru this today. The actuator in the front axel stop working. It was of course at the worse time (needed 4 wheel drive…deep snow). After checking and removing the actuator. I found out it has a fuse thats not listed as part of that system. Turns out my dog pulled out a wire and blew this fuse. My bad as I did not zip-tie that wire when I pulled power for a gage I added.

I probably engage the 4 WD once a month to make sure everything is working ok- even if it means climbing a steep bank or a dirt road. I have always been guilty of going off the beaten path every once in a while. I kind of figured that lack of use would be a bad thing so I made it a point to engage it here and there.

It’s not an electric system - I have to engage with the shifter on the floor. I always felt these systems were better to have than the “push button” type.

To me, it’s like the crank up windows vs power electric windows. Each has it’s advantages. In my experience, electric offers the vehicle the opportunity to choose the best time to engage. This could lead to a longer lived transfer case. Good arguments for both sides. I prefer manual too but i would be hard pressed to imagine the multimode drive train I have, operating as easily with one. I find that the manual linkage actually needs more not less attention and could be more difficult then a wire and a switch to repair.

Bummer. I was hoping the opposite was true! So far everything seems to be working fine and now that I live in a more rugged area I am using the 4WD system more frequently. I guess I will be changing the transfer case fluid soon.