Well here are my thought. I am actually surprised on a oil consumption problem on this engine. This is a great engine. The only thing I have seen that can cause oil consumption is the valve seals. If the valve seals are bad, it will leak oil into the cylinders and burn oil. The noise you are hearing when the oil level is low is the lifters. If the lifters get air rated, they will make a ton of noise.
You do not need to remove the cylinder heads to do the valve seals. I have done them simply by using compressed air in the cylinder to keep the valve in place.
Piston rings are the other item that can cause oil consumption issues. This is extremely rare, but can happen.
The last thing you can try, which is the first thing I would try, is replacing the PCV valve. This is for crank case ventilation. If clogged or not working properly, it doesn't allow then engine to breath properly and will also cause oil consumption. This part is cheap and the labor isn't that much either. This would be the first thing I would try.
If you have any more questions on this, please feel free to ask. thanks Jay!
If you would like to continue working with me on another one of your questions, you can request me.
Edited by Jay on 1/27/2010 at 3:27 PM EST