Lots of posts reporting good things with these diesel oils. Temps in my area of North Carolina are currently in the 70's during the day dropping to the high 30's overnight. Should only get warmer from here on until September. My local shop carries Mobil brand 15W40. I assume this is Delvac? Anyone think this is a good choice for my 2.7 four banger? Possible to run year round? Temps rarely drop below the 20'sF and we don't see single digit temps but maybe once or twice(meaning one or two days total) per year. Some years not at all. Currently running 10W30 Havoline dino with 5K OCI. No oil consumption and the color goes from light golden to light brown. Truck has 129,300 miles. Plan to do a UOA at 130,000 and change. Should I go ahead with the 15W40 or stick with the 10W30 until I get the results back?