I just purchased a 2004 WRX Wagon. I love the combo of utility/fun to drive. I drive it realitively easy but let it spool up on occasion. Anyway my father-in-law mentioned turbo cool down (letting car idle minute or two after driving) to cool oil in the turbo. From what I read the turbo is cooled by water and convention causes flow after you shut off. His experience is being service manager at Isuzu dealer and having many blown Impluse turbo's but this was years ago. I plan on using Mobil 1 every 5k. I don't drive like a nut. I plan on keeping the car a while. Do I really need to do this?