Ok I have a 08 silverado with a 10 bolt. I'm installing 4.11 gears and a value trac in it tonight. I'm wondering what fluid should I go with and how much. Also does these value trac's need any sort of limited slip additive or anything. Thanks for any input

 

Mobil-1 75W-90 or SAE Synthetic 75W90, just shy of three quarts.

 

You MUST run conventional oil, no additives. If you run synthetic then the diff may not work correctly. I use Valvoline 75w-90 with mine.

I was only able to get about 2.5 quarts in mine, and that was almost up to the fill hole. My diff is pointing down more than stock though so the oil level reaches the fill hole faster.

Remember to change the oil after 500 miles. The first drive is VERY important. Light easy driving for ~30 minutes, then let cool completely overnight. Refer to the pt.net gear swap sticky.