I think, before I would consider changing the lifter, I would run a can of engine flush through it or about a half a quart of ATF before you change the oil. My E320 would do the same thing periodically so I put a can of engine flush in it, ran it for about 20 minutes, then drained the oil (hot). I put in a thinner oil (at start-up 0W-40) and it took care of it.

It's probably worth a try before you dig into it, carbon and other deposits that are running around in an engine can sometimes clog the small oil gallery in the lifter.

Good Luck,

Dale