I don't know about the rest of you guys, but driving around Colorado, New Mexico, Arizona, Utah, etc., with 5W-30 and 10W-30 oils in the summertime makes me nervous. Maybe I am just old fashioned, but when you drive in Arizona and the temperature is 115 degrees you feel like you need 15W-40 in the engine. But the owner's manual says 0W-30, 5W-30. 10W-30, or else. With my current Saturn, you can't even use a straight 30 wt. I don't think much of Western Europe experiences Arizona temperatures, but they seem to be able to use thicker oil when the need arises. Now don't get me wrong-5W-30 is fine in the wintertime. Heck, 0W-30 in Minnesota. Maybe the answer is synthetics, I don't know.