Grease in front diff oil. OK to leave as is for a while? (1 Viewer)

[e9999]

replaced the front diff gear oil about 3K miles ago.
76K on rig, no indication that Birfs and seals were ever redone.
Oil took a definite black tinge to it. Presumably the result of some black grease from the knuckles. No indication of Birf soup coming out of the knuckles, so if the seal is weak, it seems to be only in one direction.
Had the breaters extended and opened around that time too so the diff is not likely sucking grease in from the knuckles by vaccuum.

Anyway, either there is a bit of grease coming in from the knuckles or the oil got dirtied from earlier grease remaining in the diff despite drain (unlikely).

Either way, there is some grease in the oil. Oil, at least near the top, seems very fluid still, not soupy.

Question: would a small amount of grease be detrimental and dangerous to leave in there? Heck, it has moly so could be a good thing?
More specifically: OK to leave as is for the 2K freeway run to Moab or is it imperative that I change it first?

 

[IdahoDoug]

E,

No problem. Your post confused me a bit, but I'm assuming it was changed once and was black/thicker, then you did it again recently and still found a bit of black color. This would be as you surmised, just residual grease in the housing. No worries at all if the diff is full of oil and the knuckles have grease in them. The open breathers will stop the "pumping" action whereby they pull a smidgeon of birf grease in past the axle seals each time the diff cools down from a drive.

DougM

 

[e9999]

when I changed the diff oil, 3K ago right after getting the rig, I did it because the existing oil was very black and greasy looking.
I should have checked a few days after changing it to see if it had turned black already from residuals, but didn't think about it. Somehow don't think that would be it, though.

 

[elmariachi]

Heck, it has moly so could be a good thing?
More specifically: OK to leave as is for the 2K freeway run to Moab or is it imperative that I change it first?

The problem is not so much the moly in the gear oil as the absence of moly in the knuckle. If you are really jammed for time, I believe I'd check the knuckles for moly and make sure they're fine, then check the gear oil through the fill plug again and see just how dirty it is, then decide.