I soaked the hydraulic lifters before putting them in my 240, I made sure all of the bubbles stopped coming out before installing them. Not sure if it made a difference other than cutting down on clatter upon initial start up. I have seen some posts where guys flush them with lacquer thinner first then pump oil into them. Some just use assembly lube and let the oil pump do the rest. I have never seen any negative effects from soaking them first.