I did the oil change yesterday.
Out came the Valvoline conventional 10w-30. I normally stick with 15w-40, but experimented with that as a winter oil. We do get some days with temperatures below 10 degrees Fahrenheit here in east Tennessee. So I was curious if there would be a difference in starting the car with 10w-30 instead. It was, in fact, a little easier to start the car on those very cold days than with 15w-40.
In went about 6.3 quarts of conventional Valvoline Premium Blue 15w-40. The most noticeable difference is that the 3 liter, inline 6 M103 engine seems to idle smoother with the 15w-40. Mann oil filter change, too.
Considering that most winter days here are not cold enough where the advantage of the 10w-30 over 15w-40 makes it noticeably easier to start the car, I'll probably just stick with the 15w-40 all the time from here on out.
No real preference for Valvoline, by the way. I've been using Chevron Delo and Rotella conventional 15w-40 in the past. No complaints at all with those oils, just experimenting with something else.