2001 VX 42000 miles had to add 1-quart between oil change.
I took it in to the dealer and the mechanic said he has seen this problem (1 quart burned per 1000 miles is common). Two ways of losing oil. 1-leaks through rings and is burned out through combustion. 2-engine running hot and vaporizes in engine from heat. He said it usually shows up sooner than 42000 miles and it is good that I checked my oil before it became a problem. He says the problem was clogged egr tubes which causes the engine runs hot and vaporizes the oil.
Solution:
clean egr tubes & replace pcv $215.00 (every 18 months)
Oil change every 3000 miles $32.00 (hapco additive (to clean sludge from burned oil) and durablend 5w30semi synthetic oil
check oil every 1000 miles.
I hate paying for the dealer to do all the work but at this point with the info on this forum I feel dealership documentation is the best way.