My front diff in my 96 blazer is a little noisy, I am wondering if I can put 85w130 oil in it to try to make it quieter without hurting anything.

 

What noise is it making? Is the fluid full and clean? What year is it?

The heavier fluid may help a bit but if you live somewhere cold like me then that heavy fluid may do more harm then good.

 

Welcome to the forum. Using heavier oil to quiet noise is a used car dealer trick. It's like a doctor using a band-aid to cover a bullet hole. If it's only noisy in 2 wd search the forum for 4x4 noisy in 2 wd. Specify whether 3 or 4 button system. If the noise is constant, as Brian mentioned, make sure it's full. Low levels cause bearing groan.

 

it's a 96, it moans when it's cold, cold here is 32 degrees, but it will moan until it warms up even if it's 50 degrees out. I am just trying to find a temp fix until I can afford to have the diff rebuilt