GM 1/2 ton autotrac xfer case oil

[federline]

So I just performed 4x4 service (both diffs and xfer case) last weekend. The truck is a 99 Silv 1/2 ton with autotrac. The previous times I did it, I only did the differentials (always Mobil 1 gear oil), and had the xfer case done with the auto tranny service.

I always thought that you had to use the "blue smurf oil" for the xfer case because of GM's "special friction formulation" to assist the autotrac system. But when I drained the xfer case, I got what looked and smelled like red auto trasmission fluid.

Does anyone in-the-know think there could have been any damage done? Or can you safely substitute ATF for the Smurf oil? It's not like the Smurf oil is terribly expensive, $6 per quart from the stealer, 2 qts required. I'm just curious, and possibly a little worried - but I can notice no problems with the autotrac function, just used it in the mud again this weekend.

[theoilman]

GM has transfer cases that take different fluids. First of all here's how to tell which you should use:

1. If your transfer case is an electronic shift - that is you just have a push button to control it - you MUST use the GM blue fluid.

2. If you have a manual or floor shifter use the Dexron spec - the same as what goes in your automatic transmission.

(Also GM changed from Dex III to Dex VI in 2006 with everything, a few in 2005.)

The two fluids are NOT interchangable. If yours is supposed to have the blue and it had Dexron change it back to the blue, someone has apparantly put in the wrong fluid. As to damage, unknown, but get the correct fluid back in it.

As far as I know the blue 'smurf' fluid is only available from GM.

[federline]

Thanks oilman, it is as I suspected. I appreciate the confirmation. We're all smurfed up, now.