I have 152590 miles on the car. I just paid 515.00dollars for new brakes and pads. I barely hear anything besides a little purrr. I know i am over due for a oil change but a couple of weeks ago i poured two bottles in it and the stick looked like that made it full. I have never gotten a full service check on it, not even after 50,000 or 100,000 miles. what could it be.