I know this topic has been beat into the ground but I need some more information on this PTU fluid change. I am thinking of preventive maintenance and I have a couple questions on how many PTU cases are there that the fluid needs to be changed? Once I drain the fluid or suck the fluid out do I refill a halfway or all the way for 10-15 minute drive to drain out again? What is the best fluid to do this with? I have not had any problems with my transmission or anything along those lines I have 90,000 miles on the car.