I am running Yukon 4.88s and when the fluid is below 50 degrees the front gears have a little whine to them. When the fluid is warm, there is zero whine, runs smooth, no problems. It ONLY whines a little when it's cold.
Right now being the middle of summer it never makes noise because its always above 50 degrees day and night. But this Fall when the mornings get cool again the front diff will whine until the fluid warms up then its fine. I run 75w90.
Is this something I need to fix ASAP? Why is it only whining when its cold?