Would a heavy duty dino oil give the same entended drain intervals as a synthetic? They seem very capable since they are used in the big rigs and a 10-30 would keep the warranty intact. The added bonus would be the cost is less than synthetic. I have yet to hear of a problem using these kind of oils, after all, they are SL rated. I think they could easily handle a 10,000 mile or once a year. These are diesel oils are they not? Any comments are appreciated.