For regular driving I don't see why your free dino oil change at frequent intervals wouldn't be just as good as paying for synthetic oil changes at longer intervals.
If you change your oil frequently and it's free, I'd just save the money and use your "synthetic oil" money to buy something else. Dino oil doesn't lubricate as well as synthetic, but unless you are racing your car.... I don't see why you absolutely need to waste that extra money to go synthetic.
If I had free oil change at regular intervals, I wouldn't be using synthetic today, IMO.