I am clueless about this. I have heard several people talking about changing out the rear end fluid and front end fluid on 4x4's. What are they talking about? How often should this be done? I have almost 17k on my truck and havent done it because when I take it to the dealer for service I have done what they recomend. I do a LOF at every 5K, rotate tires every 10k, and at 15K did a fuel filter, trans flush and trans filter. So what is the talk about the rear end fluid about? Thank you guys and Merry Xmas!:)

Look in your manual. It explains it and is referred to as Front differential fluid, rear differential fluid and transfer case fluid.

Rotate the tires at 5K intervals and change the oil in both differentials now. If you are worried about possible warranty issues use the $23 a quart GM grape juice in the rear. If not, go with Mobil 1, Amsoil etc. Later! Frank

The first change is recommended because of metal pieces you would find due to normal ring and pion break in. After that one then you can go back to normal maintenance.