I'm coming up on the second oil change on my new Altima at 7000, and used Mobil 1 0W20 on the first change, but am wondering what you're recommendations would be for oil and weight. I bought the car last Feb and am now just getting 6000 on it, so it will go more on time than mileage. Should I change it every six months or go longer? How long? What is everyone's thoughts on 0W20 use? The manual states to use either 0W20 or 5W30 conventional?? Could I go other directions? such as 0W30? or 5W30 syn or conventional, what is your recommendations.