I purchased a 2011 Mazda3 seven months ago, and have 21,000 miles. My local Mazda dealer has changed the oil every 5,000 miles using 5W20F oil. Every oil change the level has been a quart low. At the 10,000 mile change I ask the service manager to check the level before the oil was drained, he did and confirmed it to be a qt. low. At the 15,000 mile changed they again checked the oil and confirmed it to be a qt. low, and that we had an issue. At 20,000 miles they again said it was low but that was acceptable for my engine. The service manager just called me and said he has it in writing that 1 qt./1500 miles is acceptable for my car and I should be very pleased my car does as well as it is.