Yup, You just have to try different weights and brands of oils until you find one that works the best for you... I settled on Castrol 10W-30 Extended milage vehicle oil (Green Jug).
Important thing is to watch the dip stick ...and pack a quart or two with ya....."BH"
It could be a lot of things, including problems with the valves, rings, or a leak which you ruled out. The 3.8L has a reputation for being an oil burner there are a few things you can try to reduce oil consumption. Moving up a grade to a 30 grade oil might help. You can check the valve seals. It could also be sticking rings. I would consider pulling the spark plugs and do a piston soak. I'd do that right before your next oil change. If the rings are sticking it might help. There's a lot of information on the WWW. on how to do a piston soak and what to use. I'd read up on it if you're interested. Good luck.
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