My car is a 1988 190e 2.3 8v and I have a terrible whine coming out of the differential all the time now. It started around a month ago and I have no ideas on how to address this issue.

Yesterday, I just changed the fluid with Red Line 75 W 90 Synthetic and I know in some of the other posts it was recommended to go to a 75 W 140, but since it gets so cold here, I thought it might not be such a good idea.

Thanks in advance