Diff tuning with different weight oils is one of the most important tuning options for off-road vehicles. The higher the cst rating of the oil, the thicker the oil is. Thicker diff oils help to prevent your differential from "diffing out" in the corners, which is when the tire with less traction breaks loose and unloads. Thicker oils are usually recommended for smoother, high grip tracks, while thinner oils make the car easier to drive on bumpy and loose surfaces. Use the list above to select the oil weight you need.