If the sprockets are empty you won't hear anything, they just won't advance. The tensioners being empty, that is a different story. The main tensioner has a ratchet mechanism to stop it backing off, but the two smaller chains at the top don't have this.
If you're not running a 10w40 I would suggest that first, as thinner oil will bleed down much easier. As I said though, any path for the oil to get back to the sump could be an issue, I would be trying a different brand of oil filter first, just in case. If it still rattles, I would suspect the top tensioner on one side is worn, but I think it's an engine out job. They are mounted in a stupid spot.