E30 Zone

Hey zone.
My e30 has a loud whine on the rear that changes pitch alot I'm assuming it has something to do with the diff. The oil is old in it but I wouldn't think it would be doing that. Is it the bearing? Any help would be appreciated.

Failing fuel pump (worn out commutator) will whine, but this happens with the car moving or stopped.
Diff. input bearing can whine, as can wheel bearings. Any change in the whine when cornering points towards a wheel bearing on the inside of the corner.
Retaining nut for the diff. bearing does not have a fixed tightening torque. If the bearing is replaced without the knowledge or expertise to set up a diff., then the exact position of the nut must be marked before removal, then refitted to exactly the same position after changing the bearing, using the same nut, same washer and same drive flange.

It definitely won't be the fuel pump I've changed it. But I will look into the other stuff thank you

the whine in the rear is usually the wife