I recently bought a 2004 Dakota. The previous owner replaced all fluids before my purchase. I have a slight drip in the rear pinion. 1 or 2 dime size drips over night. I think it is slightly overfilled and not sure what weight was used. (calls for 140w). Question that I can find an answer to that maybe somebody has experience with...Will the leak occur during driving or when sitting?? I have to take the truck on a 500 mile trip and am not sure if more oil will leak when moving or when sitting still? Also...I have read bad stories of folks replacing the seal only to make matters worse. Leave it?