>>> and trips short enough for the oil not to heat up. <<<
You were doing good until you got to this point.
1) The oil heats up to temperature within a minute. The cooling system then keeps it at a constant temp for the rest of the trip.
2) Oil is hydroscopic - it loves to absorb water. The water then reacts with the oil to form acids. When the oil is heated up, it helps drive the water back out of the oil. So long trips are better than short trips for your oil life.
You are correct. My bad.