Why is my rear diff oil gray?

I checked it today, and it has a murky gray color to it. It is only 3 months old with about 3000 miles on it. I have wheeled it a couple of times, and once it was really muddy, so I am thinking it got a little water in it. I will be changing it ASAP. Any other insight as to what other problems I should check for will be appreciated.

I would change it out asap and keep a close eye on the color of the lube after you change it. It could have been caused from water, -but typically, that will cause a brownish milkshake colored lube, -not grey.

Gray colored oil is usually indicative of a bearing going south, -so do keep an eye on the oil after you change it. While you have the cover off, -look for anything obvious going on with the gears, or the carrier bearings. Don't be afraid to reach in there and yank things around, -just be careful and don't lose the end of one of your fingers! Wearing leather gloves is recommended, and if you don't have those, use clean shoprags or something, -just don't leave 'em in there.

My .02

Water

Agree with water as the contaminant, change the oil AND check the vent hose. It should be routed high enough to keep water out, but you need to make sure it's tight to the diff and doesn't have any breaks that would allow water in.

where is the vent hose on a 35?

dspilot said:

where is the vent hose on a 35?

Click to expand...

It comes off the tube and runs right into the frame. You might get some diff fluid vapors thru your back quarter area. You can actually hear it bubble if you get it hot enough. That is when you start to smell it. Change it soon if you haven't already. You don't want your gears and bearing soaking in that crap. It'll pit the shit out of them.