I just disassembled and cleaned 16 hydraulic roller lifters. I guess I finished about a month ago thank God, man those things were nasty.
Soaking them isn't going to accomplish anything that doesn't happen in a few seconds under pressure. The thing works because there is a little wafer plate at top right below the hardened cup your pushrod sits in. The wafer acts as an orifice because the OD of the wafer is maybe a thou less than the ID it fits in. I would be amazed if ANY air escaped it in a swimming pool of oil for a decade long immersion.
Then there is the hole that meets the gallery. Inside the lifter from it is the spring and piston. The piston has a ball check at the bottom that allows flow from top to bottom. Pressure will open it but not gravity. Oil isn't going in the lifter unless it is forced.
I just clean em and pour oil on them. I use Cat cam and follower EP lube if I'm of a mind to. Back in the old days I built many an engine with STP, never heard of EP lube. Never barfed a cam. Never used anybody else's flavor of EP lube. But I like that Cat stuff, it has a brush and comes in a little can. Sometimes I just put it on the lobe, sometimes on the lifter face too. Usually both I guess, and man I make a mess with that stuff
. I guess I've used it on at least a couple hundred industrial solid FT cams and use it at home if I'm not out or like I say if I'm of a mind to.
It gets like Wile E. Coyote and the Acme glue. I bet I'm a sight with half of me up inside a V-16 trying to lube the bottoms of the solid mushroom lifters. I need a new can, spilled my last one in the tool box of my truck. Sheeeesh what a stinkin mess.
I'm in tune with it makin you feel better though. Hell, I've soaked em. Can't hurt anything.