I'll check mine this weekend. Is the magnet still on the cover, or is it on the drain plug?

I just dropped the fluids in my '02 Avalanche a month before it went away, and everything was still pretty clean at 40K miles. I didn't pull the cover on the rear diff. I don't recall seeing a magnet - I was too astounded by the fact there was a drain bolt under the pumpkin.

I'll swear on my life that there is no mention of the early diff fluid change in my '04 manual... That thing was at the top of my bathroom reading material list for a least a month.

 

Okay, I just jogged through the manual here, and there is no mention on changing the differential fluids AT ALL.

This is in the "2004 Silverado" manual...

5-57 - All-Wheel Drive.
5-58 - Rear Axle and Four-Wheel Drive.
5-59 - Manual and Automatic transfer case.
5-60 - Front Axle.

Under Rear Axle and Front Axle, this is what we have:

"It is not necessary to regularly check rear/front axle fluid unless you suspect there is a leak or you hear and unusual noise. A fluid loss could indicate a problem. Have it inspected and repaired.."

It then mentions how to check the levels, and says 'see 6-13 for fluid types'.

6-4 is the maintenenace schedule, with "Maintenance I" and "Maintenance II" services. On 6-6 is the Additional Required Services with the traditional 25,000, 50,000, 75,000, etc service intervals.

There is no mention of the axles in the whole maintenance section. The t-case is, but that's it.

Weird.

For what it's worth, here are the 2004 specs on the rear diff levels...

1500: 5/8" to 1 5/8" below bottom of plug hole.
1500HD, 2500, 2500HD, and 3500, 0 to 1/2" below bottom of plug hole.

Sorry about my mis-quote above. I was thinking about the 1500 series.

 

i am speaking of the G80 "locker" rearend. comes std on 2500 HD trucks and i am not sure if 1500 trucks have that rear very much. this is the massive 11.5" rear i am talking about on this truck. and the metal was on the magnet itself.

 

Yeah, actually a lot of 1500's come with the G80 / Eaton Mechanical Locker... All of the Z71's, these SS's... and well, any other that you request it on.

It's weird that they say that about the unit... there are no real parts that wear or anything - not like a clutch pack posi.

 

any moving metal that involves friction = metal shavings. i would certainly dump the the diff fluid. if not you are looking at premature wear and tear. heck GM says to do it.