That chart is very old (1998 with some 2002 updates).
But one of the best flowing oils (regardless of weight) is Mobil 1 15W50 with a rating of -50. This chart doesn't show it, but it has very good ZDDP numbers too.
What I like about using Mobil 1 is that it is so readily available. I can go into most box stores and find it (NAPA, Advance, etc). Typically I find the most consistently low price to be at in my area is Fleet Farm (MN and WI).