I use Delo 15W40 in both of my trucks, (pick-ups - not the big over the road rigs). Currently, in my '96 Chevy with a 305 V-8, I changed the oil back in August at 107,000. Truck currently has 113,000 miles on it and oil looks good and clean. Miles are a combination of around town trips, (ten miles or less), to across the state trips, (150 miles or more).
I was using this same oil, (Delo 400 15W40) in my daughter's '95 Saturn SC1. It was doing a wonderful job of cleaning the motor. When I first started, the oil would be dark and dirty in less than 1,000 miles. In time, it got to the point that, like my truck, the oil would stay nice and clean for a long time, AND oil consumption dropped from one quart every 700 miles to one quart every 1300 miles, (I assumed it was cleaning the ring pack as even a 20W50 would not slow down the oil consumption). I was well pleased. Then she wrecked the car. And I had just changed the oil.