ok, my car is about at 10k miles now, and an A1 code popped up. so according to my manual, an A1 error code means to it is time to rotate the tires and change the oil. It also says that my car has 10% oil life. The problem is that I had my oil changed at 7k a while back. Does the code pop up based on a set number of miles, or does it actually read my oil somehow and tells me that I really do have 10% oil life? And when they say '10% oil life,' it's the quality of the oil, not the amount of the oil right?