My story on thicker oil. We had a class A motorhome, 1986 with a big block Chevy engine. Engine was between the front seats like van, stuck in a hole. Oil cap 10W30. Living in Colorado and towing a boat I thought oil was to light. Pulling the gauntlet or known as I-70 through the Eisenhower tunnel with a 4 speed trans it would run at 4-5k for a while, don;t remember how long it took to climb this. Same story on other Colorado mountain passes. It was using oil, again don't remember how much to long ago. Enough that I switched to Valvoline 20W50 racing oil and a 2 quart spin oil filter to get another quart of oil capacity. I always let it warm up after starting it for 5- 10 mins depending on temperature. Oil use stopped.