i have a 97 oldsmobile with the 3.8 liter and over 308,000 miles and it does not burn oil only when I tried to use 5w-20 in the summer did i notice a little consumption-about a 1/2 quart in my normal 4-5k oil change interval. running 5w20 in the winter now for it's 5th year and so far so good,,,so depending on vehicle and care you may be surprised how long you can keep them running well.
i have not read this whole thread and not sure what you are trying to accomplish, but you may look into the liqui moly oil additives, i am going to begin using the MOS and MOS2 products for my own personal evaluation here real soon.