I won't go into my long spiel of why I use Mobil 1, but suffice to say I proved its value to my self in real world driving and have used it since 1978. That said, although you can drive more miles between oil changes, even synthetic oil has a limited life span. Amsoil, which happens to made from Mobil stock, recommend a maximum of one year regardless of the mileage, and that's the measuring stick I used with my 06 Silverado even though I had a dual filtration bypass oil system on it. While the oil stays good, the additives in it are used up and/or breakdown, plus the oil becomes contaminated with acids during the year, hence the one year limitation.
On the other hand, if I used standard oil instead of synthetic, I would change it per the manufacturer's recommendation - period. In either situation, save your receipts and don't rely on dealer's records. My dealer indicated I had the truck in several times for oil changes, which was an absolute mistake. The truth was I took it in one time for a maintenance item that required removal of the oil pan, and even then, I took my own synthetic oil with me. If they can make a mistake about changing it too many times, they can just as easily make a mistake and not record it.
