A buddy of mine has a small shop. he was changed a person oil every 3k miles with off brand oil. It was always about 1/2 qt low when it came in for oil change. it was somthing like a 96 or lincoln. After changing to Motorcraft 5w-20 it has not used any oil since. It comes back in every 3k miles on the full mark. Coensidence or oil????????????????????????