Any idea what lubricant is supposed to go in the front axle of a 2000 Astro AWD?

I'm draining all the fluids for the 30K service, and the manual doesn't really clearly state the required fluid. All I can tell is that it isn't gear oil (so no Mobil 1 in that end).

I know the transfer case is GM Auto-Trak II (got that) and the read axle is AGMA/API GL-5 (got that in Mobil 1 syn), and of course the transmission is Dexron III (got synthetic for that, too), but I'm not sure the red stuff in the front axle is Dexron or another proprietary oil like the Auto-Trak II. Any help?

As a side note, in case you didn't know, there is an INTERNAL GM TSB on the transfer case oil. It seems that some transfer cases are prone to shudder on accelreation, and the "fix" is to change from the original Auto-Trak to the newer Auto-Trak II ( at $7.80/quart - ouch). The new stuff was the production fill on 2002 vans and newer. That bites for me.

 

I'll ask about that on the Astro forum...

 

Never mind - got it....

 

Was it the synchromesh stuff?

 

Actually, no. It is supposed to be plain old gear oil (Mobil 1 75W90). During the course of our relocating, the vehicle became due for routine service when I had no time (nor place) to do it. I had the wife take it to a quick-lube place, where they generally top off all the fluids. The Mobil 1 oil change ($66.00 - Ouch!) apparently also included their topping off the front axle with auto trans oil. I'm thinking they're too used to seeing T-56s and FWD cars that use ATF in the gearcase, and just assumed. That explains the sulfur odor from regular gear oil, plus the reddish tint. I knew it wasn't supposed to be ATF, but the manual only gave a GM part number for the oil. ¿?

Needless to say, it got the M1 gear oil, and I won't be going back there any time soon. Then again, I hope I won;t be moving again for a while. What a PITA...

 

You got my attention with the "proprietary oil" part. Unless things have changed recently, if a manufacturer requires a service part or lubricant that you can only get from them, then they have to provide it at no charge (installation not necessarily included).