 I have owned my Nissan Altima 3.5SE for over 2 years now, and have had nothing but FUN in this car.  I test drove a 2.5 and a 3.5 at the dealership when I was buying and after experiencing the thrust and power of the 3.5 I had to have it.  The car now has just over 50k miles on it, and have had NO PROBLEMS at all - that being said I have only ever used Mobile 1 Synthetic oil, and 91 Octane fuel and the car has purred without hiccup for me through the duration of ownership.  I have taken multiple long distance road trips, and I really just cant get enough of the performance ride.  Seriously no matter at what RPM or speed you are at there is plenty of power to spare-I HIGHLY RECOMMEND THIS CAR