A Honda technician friend who does a fair bit of racing as well swears by the following for his Honda/Acura vehicles. ( All high-revving 4 cyl). M1 15W50 in the summer; M1 0W20 in the winter. He knows all about Honda and Ford's shift to xW20 year round; The dealer he works for uses only the recommended viscosities. He thinks otherwise, and when I asked him why, he said: 1) M1 15W50 is on the thin side of the 50 weight range...it's not THAT thick. 2) You really need thick oil protection when its hot, and in stop and go traffic...BECAUSE stop and go means fairly heavy engine load when oil pressure is lowest and oil temps are highest. Near idle and with minimal cooling airflow. You don't have sufficient oil pressure at these low revs, so thicken up the oil to make up for it. 3) You NEED flow when it's cold. Getting the oil flowing to all critical engine parts is the MOST important aspect of winter oil. He also said that most of the time on cold winter days the oil never gets to its designed operating temp, so the thinner 20 weight is actually behaving more like a 30+ weight anyway... Interesting comments from a Certified technician who seems to actually know something about oil... I found the connection between engine speed and oil pressure to kind of make sense. Thoughts...?