Having my first "complimentary" oil change tomorrow. I am only at the 4900 mile level, but I am leaving the area for a few months, and will reach 7500 miles when I am gone. Not sure what oil came with the car, but expect that during the so called "complimentary" maintenance of oil change, filter and tire rotation that I will be prompted to go with synthetic oil. What are the thoughts on synthetic at this point? Good way to go, or not necessary extra cost?