Hello everyone. Since the weather is nice I figured it would be a good time for a gear oil change. I know somewhere in the TMs it says to use 80w90. However, would 85w140 conventional or 75w140 synthetic be better? I figured the thicker oil might protect better than 80w90 but if I need to stick with 80w90 I will. Either way, I know if it ain't broke, don't fix it and I don't want to have to be replacing axles for ANY reason. Thank you so much!