differential noise

[dastang2]

the other day i was under the car putting some locktite on the driveshaft bolts and i got to thinking if the previous owner ever checked the rear end fluid. so i opened it up and there was none and the magnetic plug had about 1/4 inch of metalic sludge on it. i wiped it off with my fingers and held it about an inch away from the mufflers and it lifter off my finger and stuck to the muffler. i filled it up with 80w90 and now i can hear i whining noise when i am going slow over the dirt driveway bumps and sometimes going down the road at about 70 it really gets loud and lasts for a few seconds and goes away. it is coming from the back, so i thought it was the E brake sticking so i pulled it barely while going 70 and it did not make a noise. i slammed it up and down to get it unstuck but nothing happened. so i wannna know how and why it just started after putting oil in it. how can i stop it. 95 5 spd

 

[Gault]

My guess would be bearings.

How to fix? Tear it apart and inspect, replace worn parts.

Why now after adding fluid? Coincedence most likely, it was probably going out and now the fluid helps conduct the sound better or you are now listening for it.

 

[Blown3.8]

did u add friction modifier..its needed to keep the rear quiet.if u just added the oil then u need to add some

 

[dastang2]

then that may be it then i just put in the oil. it does not do it all the time. i tried to make it do it for somebody today and it would not. it for sure does it in the morning when i first leave the spot where i park