Newbie to DIY oil changes looking for some suggestions. I have a 1991 Camry 5spd 4cyl with 150k miles. I use it to drive to the subway during the week, about 1.5 miles each way and some occasional short trips on the weekend. Should I aim for a 5w-30? Are synthetics or high mileage oils worthwhile? Previous owner was pretty consistant with his changes, although I don't know what he used. Any thoughts?