I dont consider them to be porous to where soaking them would be of benefit & the old caveat I remember was not to pump them full of oil via the side hole w your oil can. I would want the lifter bottom clean so I can goop it with cam lube and I put the lifter in then raise it up & goop the bottom to avoid any possibility of cam lube getting on the sides which might keep the lifter from rotating which is critical and during mockup w the lifter and it's bore clean & lightly lubed w WD40 I raise each lifter up off of the lobe & let go & it should fall onto the lobe w a "thunk" & if not the lifter bore clearance is too tight & needs to be honed so that the lifter can easily rotate which is critical along w proper breakin oil/aditives and taking out the inner spring (for the breakin)