differential rear diff oil black slime ?

[sweetk30]

long time and dont recall . but is the black tar like slime in the bottom of the diff from lack of oil changes and overheat of the gear oil and its just gone bad ?

i was changing the rear cover on my new to me service truck and oil looked o.k. but the bottom of the diff was a black thick slime like tar stuff . its a open diff no clutches .

EDIT : more on post 4

 

[shock88]

if it’s original from factory, it could be bearing/gear metal from breaking in. Is it magnetic?

 

[Wes Harden]

Dirt from many expansion contraction being drawn in the vent

 

[sweetk30]

its all rinsed out now best possible .

filled up with oil and will run a few weeks and pull it and swap on new cover i have coming for it and brand new fresh synthetic oil for it .

its a dana 80 4.63 gear ratio in a c3500-hd med duty truck . i think they skipped the oil change service on it . these run heavy and hot so oil changes are shorter than regular pickups . i got a dana / spicer aluminum fined cover for it to help with heat .

 

[tarussell]

its all rinsed out now best possible .

filled up with oil and will run a few weeks and pull it and swap on new cover i have coming for it and brand new fresh synthetic oil for it .

its a dana 80 4.63 gear ratio in a c3500-hd med duty truck . i think they skipped the oil change service on it . these run heavy and hot so oil changes are shorter than regular pickups . i got a dana / spicer aluminum fined cover for it to help with heat .

I put one of those OEM Ford Dana 80 finned aluminum covers on my ‘02 Dodge D80 after the first 500 miles and every time I dropped the cover for fluid changes the synthetic oil looked absolutely amazing - felt like I was wasting perfectly good oil by changing it.
Those covers dissipate heat very well.

 

[sweetk30]

I put one of those OEM Ford Dana 80 finned aluminum covers on my ‘02 Dodge D80 after the first 500 miles and every time I dropped the cover for fluid changes the synthetic oil looked absolutely amazing - felt like I was wasting perfectly good oil by changing it.
Those covers dissipate heat very well.

Just got go watch out . There is a few options on fill hole position . 1st cover i got was below centerline . My rear needs at centerline . So i found the other part# and its on its way . The other is in box for return .

 

[tarussell]

Mine was at center line position too - the higher fluid level helped as well.
I used a ‘02 F-450 S/D as the application when I ordered mine through a Ford dealer and on the same day I ordered the Dodge truck - the cover came in three days later but the truck took three months to arrive.

Truth be told every rear diff should come with covers like these - not including rock crawler applications of course.

 

[sweetk30]

Mine was at center line position too - the higher fluid level helped as well.
I used a ‘02 F-450 S/D as the application when I ordered mine through a Ford dealer and on the same day I ordered the Dodge truck - the cover came in three days later but the truck took three months to arrive.

Truth be told every rear diff should come with covers like these - not including rock crawler applications of course.

i think someone severely over looked oil change on this in the rear end . looks good cleaned out . will see sound and feel on road test .

it has a massive service body in the back end with a ford 302 v8 air compressor . and the amount of tool box areas was crazy . i would think it was LOADED heavy its whole life . my line of work now will be a cake walk for it .

 

[obijuank5]

I have heard that it is like soot from overheat and oil breakdown. Zero credibility on that but seems plausible.