I bought my car over 6 years ago and have put synthetic in it ever since. At some point, I figured out that it cost me X amount of dollars to change it myself, for less than 10 more, I can have my mechanic do it - and he checks over the car, tops off the coolant and wiper fluid, and rotates the tires. Where this has helped me is that I know when things are coming due for maintenance and I can start putting money to the side for the expensive stuff. For example, when my timing belt started looking bad, he told me I had an easy 10k miles before I really had to worry. Three months later I had the 350 he was asking to do it, well less than the miles he recommended. But I believe I'm lucky that I have a good mechanic who is honest and will always take the time to talk to his customers.