Re: Differential Oil Change - How the Heck?!

Posted by DrewLA On 2015/10/3 11:48:07

+1 for GL-5 85W-140. At the expense of slightly reduced fuel economy (maybe a fifth of a mpg), you'll get longer wear out of your differential because metal to metal contact will be almost completely avoided. My rear end shop recommends that grade in everything he does.

To those who think it would be too thick, remember: 140 is one step higher in viscosity than 90. For reasons passing understanding, gear oil viscosity skips from 90 to 140. Click on the link below for a comparison chart. Gear oil and motor oil viscosity are measured differently, in fact a 90 weight gear oil is about the same Saybolt viscosity as SAE 50 motor oil.

Oil Viscosity Chart | Bob is the Oil Guy