Clifford is completely wrong. The lifters are inflated by oil pressure constantly, which must enter through the feed hole in the "waisted" area. Pouring oil on top does nothing. The lifter will collapse (and shorten) if the pressure is interrupted even momentarily.
When that happens, the pushrod is dropped to the new (lower) height, which adds a huge amount of lash to the rocker arm adjuster. If run like this, the parts will be ruined very quickly.
Don't even think about it.
