There are at least two versions of "Sway", which complicates the whole process. Anyone who has driven an overloaded pickup will know one variation. The steering feels like the front end is off the ground and the rear end swerves from side to side. That is the one that people confuse with sway caused by trailer problems. WD might help a little with the overloaded rear axle, but won't cure a swaying trailer. Sway control won't help an overloaded tow vehicle from wallowing down the highway. Two different scenarios, two different cures.
