I am going to do an oil change and was also going to change the oil in my the differentials. I have a 06 1500 4x4, and I was wondering what kind of gear oil I need for the front and rear diffs and how much oil for each.

 

Well I am assuming 75w140, unless Dodge changed the weight of oil recommended. And generally half-ton axles have a 2 to 2 1/2 quart capacity (may have changed with newer rigs). If your truck calls for friction modifier (which I am sure it does) then buy Royal Purples 75w140 since it already has the friction modifier in the gear lube.

Amsoil's 75w140 does not have the friction modifier in it which I think is dumb for the money you spend on a quart. If you can not find the correct gear oil in the forum such as FAQ, or from somebody a rig like yours, call the Dodge dealer.