New owner rear end / front end oil change?

[JackStone]

My friend bought a 6. 7 4x4 12k miles. The book says we need to change the front and rear end grease. We can't find what kind of oil to buy or if any additives are needed. Also is there any need to use synthetic oil in the engine? Thanks Jack

 

[TroyWood]

AMSOIL 75W110 Severe Gear is popular

I used Royal Purple Max-Gear in both of my diffs.



as for the motor you have to use a Ultra Low Sulfur Diesel type.

 

[bruiserbob]

Friction Modifiers

Also, even if you have a limited-slip differential, the manual says that it is not necessary to add a "friction modifier"... ... ... ... ... .

 

[DeezelDood]

Also check TSB's. I don't know if they corrected it for 2007 but the fill holes for the AA diffs on the 2006 are about 3/8 inch too high. If you fill all the way to overflow the gears will foam the oil. Rule of thumb is tip of pinky finger. When I changed my front diff oil at 15k miles it was oxidized. I'm pretty sure it was overfilled at factory.

 

[dlmetzger]

My friend bought a 6. 7 4x4 12k miles. The book says we need to change the front and rear end grease. We can't find what kind of oil to buy or if any additives are needed. Also is there any need to use synthetic oil in the engine? Thanks Jack

It is in the owners manual. I found this in my 2008 owners manual:



"Front and Rear Axle Fluid 2500/3500

Models

GL-5 SAE 75W-90 Synthetic or equivalent. Limited slip additive is not required. "