At 166,000 miles, it is now using more than 1 qt per 1000 miles. Used to go 6000 without using any. Changed every 6000 with M1 5w20 and K&N filter. The oil use seems to have started at about 130,000, and is steadily getting worse. Jeep claims PCV valve has been replaced every 30,000 as part of regular maintenance. Any ideas?