I have a '99 V10 in my SD with about half the miles on it as yours does. I bought it with 12 miles on it. I've never had the kind of noise you've heard with yours, but it isn't a quite engine by any means.
With a 40w it's only felt sluggish. With a 20w it seems fine. I normally use a 5w-30. PYB, Quaker State, M1, GTX, MC, PP, they've all worked ok. It's just a big happy engine with about anything, in my experience.
I normally use a Purolator filter, 3k mile changes, and consumption is in the normal range. I like my V10.
I will add that about 15k miles ago I tried the ARX treatment. What I could see down the oil fill tube wasn't too terribly bad, kind of a medium brown. After I did the ARX it was almost shiny as new. I was impressed, to say the least. If there was nay sludge, it had to have been removed.