Chevy Silverado and GMC Sierra Forum banner
Status
Not open for further replies.

Black Fluid from Differentials

1K views 4 replies 3 participants last post by  EKinMN 
#1 ·
I have an '08 Silverado 1500 4x4 with 50,500 miles. Yesterday I jacked it up in the garage and changed the fluid in both the front and rear diffs. I used a suction device to pull the fluid from the rear fill hole and the front had a drain plug.

Both diffs had really dark, almost black fluid in them. Is there a factory addative used that would do this to the gear oil? I know it has never been changed since new. When I wiped some spillage up with a rag it looked almost like there was silver anti-sieze in it.

BTW I filled the front with 80w-90 GL5 Valvoline and the rear with 75w-90 Synth. Valvoline.
 
#3 ·
50k seems a bit too long. Do you tow a lot? I would aim for 25k diff changes.
 
#4 ·
I'm relieved to know it is normal for it to turn dark. Compared to the nice, clean golden fluid going in it was nasty. I thought maybe it was either contaminated or there was a break-in additive put in by the factory. On the plus side, there were not many metal shavings on the magnetized drain plug.

I intend to change the fluids regularly, but the truck is new to me so I wanted to do all the fluids now just so I know when they were last changed as I don't have any records from the previous owner.

The tranny is next. Although with the snow in the forecast it may be a couple more weeks until I get to it. Nothing worse than rolling around on a cold, wet garage floor while trying to avoid getting petroleum products in your eyes.
 
#5 ·
Definitely true. Winter time maintenance is tough. I don't blame ya for waiting. I hate those cold wet floors!
 
Status
Not open for further replies.
You have insufficient privileges to reply here.
Top