About 6 months ago, I discovered that my 1999 Corolla was burning oil. I have the oil changed every 3,000 miles pretty consistently, drive about 400-500 miles a week and have at present 169,000 miles. I had the car serviced 2 weeks ago and today it was bone dry. I have been checking regularly each week and for several months I need to put in about 6 quarts of oil between the 3,000 mile oil changes. There is no oil on the ground, no significant leaks visible in the engine, no blue smoke pouring out the back. I have a reliable mechanic who is mystified by the problem. I would be grateful for any clues to solve this mystery.
Thanks for any help or advice you can give!