dropped my 13 pp off at the service dept at the ford dealer I work at. I have the same cooled ptu as the interceptors, and ford states that those should have the fluid exchanged every 30k miles, but not the civilian models? anyways, I am at just under 58k miles, and having the ford 75w140 replaced with amsoil 75w140. the fluid cost me $18 or so, and the labor will be about $46. hopefully things pan out. maybe i'll even notice an improvement of some sort! I plan on doing it every 30k, which is basically at least once a year. I bought the car used in july 2015 with 27k miles.