My daughter has a 2004 TSX that intermittently losses 2 quarts of oil
in 500 miles. No external leak seen, tailpipe is clean, no blue
smoke. Dealer has done cylinder pressure check (normal all
cylinders), changed PCV valve. and finally given up. She drives 70%
highway/30% city. very conservative driver. Like I said it's
intermittent. Sometimes 500-800 miles w/o significant loss (< 1/2
Qt.) and then losses 2 Qts in 500 miles. She's ready to dump the
car.

Any ideas?

Thanks.