My 98 V70 AWD with 120K miles has been using oil for the past 4 months. The dealer doesn't know what could be doing it, they have replaced a fairly inexpensive gasket in or near the turbo, but the problem never went away. The next steps to find the root of the problem are in the thousands of dollars and apparently do not guarantee they'll find the problem. I am losing about a quart of oil every two to three weeks. We drive in heavy traffic all the time (Washington DC) so it's stop and go. The only thing I've noticed is some gray smoke coming out of the tail pipe first thing in the morning (regardless of outside temperature) every once in a while. I have yet to see a drop of oil on the garage floor. I also think I lose more oil when the A/C is running, but could be just my imagination.

A friend of mine suggested switching to synthetic oil might reduce the oil dissapearance, he was not willing to go into details as to why... Is there any truth to this? Also, can anyone venture I guess as to what might be happening to my car?

Thanks!