Electronic Transfer Case Fluid?

[TurboDiverArt]

Hi All,

I've been slowly finishing up all the maintenance on the Suburban and topping off fluids. Rear diff was fine but front was low by about 1/2 a quart. I doubt the 4-wheel drive was engaged much in its lifetime.

Anyway, I'd like to check/top off the transfer case fluid. It's a 1999 with electronic transfer case controls. If memory serves me, the manual says to use 80w with manual transfer cases only. Gives a GM part number for the electronic version. What type of fluid can I use in a 1999 K2500 electronic transfer case?

Thanks,
Art.

[DmaxMaverick]

It should be ATF for all transfer cases, except for Autotrac (check on that one). Push button (2hi, 4hi, 4lo) is electronic controlled, not Autotrac. If you have an "Auto 4 x 4" selection, then it's Autotrac. Gear lube will result in early overhaul with either of them.

[TurboDiverArt]

Originally posted by DmaxMaverick:
It should be ATF for all transfer cases, except for Autotrac (check on that one). Push button (2hi, 4hi, 4lo) is electronic controlled, not Autotrac. If you have an "Auto 4 x 4" selection, then it's Autotrac. Gear lube will result in early overhaul with either of them. My 1999 Suburban 2500 has 2H, 4H, 4L and Auto 4WD. I figured it didn't use gear oil but I'm not sure what type to use. I think the manual says that Auto 4WD locks the front hubs but runs off the rear tires until it somehow determines you need to engage the front as well. Says you get worse gas mileage than 2H but better than 4H. Didn't know it was called Auto Track. I just assumed it was standard, my Burb is an LT so maybe that's why. I don

[larsajoh]

You have the Autotrac, I'm quite sure it is recommended to use the original GM stuff in them. Don't know what it is since I have a 97 Tahoe, and it doesn't have Autotrac.

[DmaxMaverick]

You do have the Autotrac. The dealer is the only place that I know of to get Autotrac (or currently Autotrac II) lube. It has special friction modifiers and other additives in it to accomodate the engagement synchro's and clutches that make Autotrac possible. Autotrac is a system, computer operated, that monitors traction (or lack of) at each wheel and provides torque to the front axle when needed. Kinda' like a locker between the front and rear.

[Dimsdale]

Yes, you have Autotrac. You need the blue Autotrac II fluid, about 2-2.5 quarts at 7 bucks a quart.

There is also an upgrade to the fill/drain bolts. You should buy those and replace the old ones. The old ones take a metric (or so they tell me) insert, like a ratchet wrench (I thought a 1/4 inch was correct, but they are aluminum and easily strip out. The new ones have bolt heads. Watch the torque on reinstallation. Do NOT use steel or any bolts made of anything but aluminum in the magnsium case. And don't use a torch to heat the original plugs if stuck. Magnesium burns, and quite well!

[TurboDiverArt]

Thanks for all the info! I'll pick up fluid and new bolts when I'm at the dealer next week.

Art.