So my friend just came to me and asked me why her 2003 Jeep Liberty Renegade with the 3.7L is consuming massive amounts of oil. She said at 2.5k miles after her oil change she had to put in 2.5 quarts of oil. She says there is no residue in her driveway and that she doesn't have a difference in mileage or exhaust color and smell. What do you guys think it might be?