Originally Posted by vladconnery

Front: Thinner/lighter fluid in the front differential increases off-power steering. You must be careful not togo too light as the steering will become grabby and inconsistent. If you experience this go one step heavier.
In general, thicker/heavier front differential fluid increases off-power stability and increases on-power steering.
Center: Using thinner/lighter fluid in the center differential tends to make the model easier to drive on
rough and slick tracks but allows it to unload easier under acceleration and provides less forward drive.Thicker/heavier center differential fluids offer better acceleration, increased on-power steering and lessoff-power steering. In general, using thicker center differential fluid is better on high bite and smooth tracks.
Rear: Using thinner/lighter fluid in the rear differential provides more corning traction and increases steeringresponse in the middle of the turn. Thicker/heavier fluids in the rear differential provide less steering in
the middle of the turn but greater forward traction.